DESC:METHOD OF WELD QUALITY IMPROVEMENT
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202421014548 filed on 28/02/2024, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
Generally, the present disclosure relates to welding. Particularly, the present disclosure relates to a method of weld quality improvement.
BACKGROUND
Conventional welding processes, such as arc welding, MIG (Metal Inert Gas) welding, TIG (Tungsten Inert Gas) welding, stick welding, and gas welding, have been used for decades in various industries for joining metals and/or alloys. The welding processes typically involve the application of heat to melt and fuse two workpieces, using a filler material, to form a permanent joint.
The arc welding is the most common welding process. An electric arc is created between an electrode and the workpiece, generating strong heat to form a weld joint. The MIG welding uses a consumable wire electrode and a shielding gas to form the weld joint, and the TIG welding uses a non-consumable tungsten electrode. The Gas welding, or oxy-acetylene welding, uses a flame generated by burning a mixture of oxygen and acetylene gas. The processes mentioned above are versatile and widely used in construction, manufacturing, and maintenance in various industries.
However, there are certain problems associated with the existing or above-mentioned welding processes. For instance, heating distortion and bending of the workpiece due to the intense localized heat input is a significant issue, which compromises the accuracy and strength of the weld. Additionally, the above-mentioned processes lead to the formation of a heat-affected zone (HAZ), reducing the mechanical performance of the joint. Further, the problem of heating spatter, particularly in processes such as MIG and stick welding, leads to excess molten metal outside the weld joint, requiring additional clean-up. Furthermore, safety hazards, such as exposure to intense UV radiation, fumes, and electric shock, are inherent to conventional welding techniques.
Therefore, there exists a need for a method of improving weld quality that is efficient, robust, and overcomes one or more problems as mentioned above.
SUMMARY
An object of the present disclosure is to provide a method of weld quality improvement.
Another object of the present disclosure is to provide a method of weld quality having a uniform weld joint, and improved fusion between the metals.
In accordance with an aspect of the present disclosure, there is provided a method of improving weld quality between two metals selected from a first group and a second group, wherein a first metal is selected from the first group and a second metal is selected from the second group, the method comprising:
- pre-weld heating the first metal and the second metal;
- welding the first metal and the second metal to form at least one uniform weld joint; and
- stretching the at least one weld joint by applying a uniform force along a transverse axis of the weld joint.
The method of improving weld quality, as described in the present disclosure, is advantageous in terms of providing a stronger and more reliable bond between the metals by utilizing a combination of pre-weld heating, uniform welding, and post-weld stretching. Particularly, the computation of a residual tensile determines the metal behavior under varying levels of stress. Consequently, the residual tensile strength allows for the optimization of the welding process and predicts the weld joint performance. Further, the prediction of the weld joint performance allows a pre-weld adjustment to minimize any potential weakening of the weld joint.
Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
Figure 1 illustrates a flow chart of a method of improving weld quality between two metals selected from a first group and a second group, in accordance with another embodiment of the present disclosure.
Figure 2 illustrates a bar graph for a comparison of tensile strength, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
As used herein, the term “welding” refers to a process of joining materials, such as metals or thermoplastics, by applying heat, pressure, or both. The process involves melting the base material and adding a filler material to form a weld joint that solidifies and cools to form a strong bond. The welding is performed using various techniques, each suited for different materials, joint configurations, and applications. Various types of welding include such as, but not limited to, arc welding (such as Shielded Metal Arc Welding or SMAW, and Gas Metal Arc Welding or GMAW), gas welding (oxy-acetylene welding), Metal Inert Gas (MIG) welding, Tungsten Inert Gas (TIG) welding, laser welding, and spot welding. Each type of welding process utilizes different energy sources such as electric arcs, gas flames, or lasers to melt and fuse materials. The basic components of a welding setup include the power supply to generate the heat, the electrode or filler material (used to fill the joint), and the welding torch or gun (to direct the heat and filler material to workpieces). In the welding process, the heat melts the base materials at the joint, and the filler material is added to fill the joint. Subsequently, the heat is removed, and the molten pool solidifies, forming a durable, fused bond between the two pieces. For certain types of welding, such as arc welding, an electrical arc is formed between an electrode and the workpiece, creating the required heat. Different welding processes offer various advantages, such as speed, precision, or the ability to weld different materials.
As used herein, the term “metal” refers to a class of solid elements that conducts heat and electricity. Specifically, the metals used in welding are categorized into ferrous metals (containing iron) and non-ferrous metals (without iron). Ferrous metals, such as, but not limited to, carbon steel, stainless steel, and cast iron, are used in welding because of their strength and ability to be welded effectively. Further, non-ferrous metals, such as aluminium, copper, brass, and nickel alloys, are commonly used in welding. In welding, the components involved include the base material (the metal being welded), the filler material (used to fill the joint), and the flux (which protects the molten weld pool from contamination). The metals are selected based on compatibility, as different metals react differently to heat and require specific welding processes. For example, aluminium requires TIG or MIG welding due to low melting points and high thermal conductivity, while steel is welded using MIG or SMAW methods. During welding, the metal is heated until the melting point, and solidifies, forming a solid joint. Proper welding parameters such as heat, pressure, and filler materials are adjusted depending on the type of metal being welded to ensure a durable and high-quality weld.
As used herein, the term “first group” refers to ferrous metals, which primarily contain iron as the main component. The metals from the first group are used in welding due to the strength, versatility, and ability to form strong bonds during the welding process. The main types of ferrous metals include carbon steel, alloy steel, and stainless steel. The carbon steel is made primarily of iron and carbon and is used in a wide range of industries. The alloy steels are carbon steels with added elements such as chromium, nickel, or molybdenum, which improve specific properties such as strength, hardness, or resistance to corrosion. Specifically, stainless steel with corrosion resistance properties is also used in welded ferrous metal, especially in applications requiring durability in harsh environments. The metals from the first group require precise control of heat input due to the specific melting points and tendencies to form brittle zones at high temperatures. Common welding methods for ferrous metals include Shielded Metal Arc Welding (SMAW), Gas Metal Arc Welding (GMAW), Gas Tungsten Arc Welding (GTAW), and MIG (Metal Inert Gas) welding. For instance, carbon steels are welded using MIG or SMAW, and stainless steels are welded using GTAW for better control over heat and precision. During welding, the base metal is melted at the joint, the filler material is added, and the molten pool solidifies, forming a durable bond between the metals. The choice of welding technique and consumables depends on the specific type of ferrous metal and intended application.
As used herein, the term “second group” refers to non-ferrous metals lacking iron as a main component. The metals from the second group are more resistant to corrosion and have unique properties that require specialized welding techniques. Common non-ferrous metals used in welding include aluminium, copper, brass, bronze, and nickel alloys. Specifically, aluminium is widely used due to its lightweight and corrosion resistance properties and is welded using TIG (Tungsten Inert Gas) or MIG (Metal Inert Gas) welding. Further, copper is known for high thermal and electrical conductivity, and brass and bronze are used in applications requiring corrosion resistance and high strength. Due to the different properties of non-ferrous metals, such as lower melting points and higher thermal conductivity, welding requires precise control over heat input to prevent issues such as warping or burn-through. For instance, aluminium welding often uses TIG welding because aluminium provides better control over heat and allows for precise welds. The welding of non-ferrous metals also involves preheating, proper joint preparation, and specific consumables that match the metal to ensure strong, high-quality welds.
As used herein, the term “pre-weld heating” refers to a process of applying heat to the welding materials being welded before the beginning of the welding process. The pre-weld technique is used to reduce the risk of cracking and other welding defects, particularly during the welding of high-strength steel, thick sections, or dissimilar metals. The heat helps to reduce thermal stresses during welding by minimizing the temperature differential between the weld zone and the surrounding material. The pre-weld heating is particularly important for materials that are susceptible to hydrogen-induced cracking or have a high carbon content, such as carbon steels, high-alloy steels, or certain cast materials. The types of pre-weld heating include local heating (heating the specific areas to be welded), uniform heating (evenly applying heat across the entire workpiece), and induction heating (using electromagnetic fields to heat the material). The primary components of pre-weld heating include heating equipment (such as flame torches, induction heaters, or electric resistance heaters), temperature measurement devices (such as thermocouples or infrared pyrometers), and the workpiece (the material to be welded). The process involves applying controlled heat to the base material before welding to elevate its temperature to a specific range, typically between 100°C to 400°C, depending on the material and welding procedure. Consequently, the reduced temperature gradient between the heated area and the surrounding material helps to prevent thermal stresses that cause cracking or distortion. Pre-weld heating is beneficial for welding thick or high-carbon materials, as pre-weld heating allows for better penetration, smoother welds, and reduced cooling rates, ultimately enhancing the strength and integrity of the finished weld.
As used herein, the term “weld joint” refers to a welding junction between two or more pieces of material being joined together through welding. In particular, a pre-joint is prepared before welding by cutting, bevelling, or cleaning the edges of the materials to ensure a strong, continuous bond. The weld joints are categorized based on the relative position of the parts being joined, namely, butt joints (two pieces are placed end-to-end), lap joints (one piece overlaps the other), T-joints (two pieces meet at a right angle), corner joints (two pieces meet at a corner), and edge joints (the edges of two pieces are aligned). The type of weld joint depends on factors such as, the material being welded, the required strength, and the welding process applied. The main components of a weld joint include the base material (parts to be joined), the filler material (material added to form the weld bead), and the weld throat (throat of the weld is the smallest cross-sectional area of the joint). The welding is performed by applying heat and pressure to melt the base material and fuse it, with the filler material contributing to the formation of the weld. The molten material solidifies to create a strong bond between the workpieces. The configuration of the weld joint determines the type of welding process used, such as MIG welding for butt joints or TIG welding for precision corner joints. Proper joint design and preparation are essential to ensure a strong, reliable weld that meets the mechanical and performance requirements.
As used herein, the term “transverse axis” refers to an axis that is perpendicular to the length of the weld joint. The transverse axis is used for testing the strength or alignment of a weld when forces are applied along the axis to evaluate the weld’s performance under stress. The test is used to assess the weld's resistance to stress that is applied perpendicular to the weld joint. The transverse axis plays an essential role in determining the structural integrity of the welded joint when subjected to forces or loads that act across the joint's length. The primary components involved in testing along the transverse axis include the weld joint, the applied force (mechanical or hydraulic), and measurement devices (such as strain gauges or displacement sensors). When a force is applied along the transverse axis, the weld's ability to resist deformation or failure is tested, providing data about the strength and durability of the weld under stress. In practice, during welding, the transverse axis defines the path of force application when adjusting the weld for uniformity or assessing the strength, helping to ensure the weld's performance and the material's structural integrity across the joint.
As used herein, the term “first applied force” refers to an initial force applied to the welded joint before the welding metal undergoes plastic deformation. The first applied force is applied in a controlled manner and is less than the yield strength of the base material so that the welding metal does not undergo permanent deformation. The primary purpose of the first applied force is to apply light stress to the weld joint to ensure that the material is in place and free from defects before applying higher forces or completing the final welding process. Types of first applied forces include but not limited to clamping forces (to hold the materials together), pre-stress forces (to control distortion during welding), and tack forces (to temporarily bond the metal for further welding). The components involved in applying the first force include mechanical or hydraulic devices such as, but not limited to clamps, jigs, or presses, which exert a precise and controlled force on the workpieces. The force is applied to ensure proper alignment, fit-up, and pre-stressing of the materials, helping to minimize distortions, gaps, or misalignment during welding. The first applied force works by maintaining uniform pressure on the joint, preventing movement of the workpieces during the welding process. The force does not exceed the yield strength of the metals, allowing the base materials to remain in the elastic phase.
As used herein, the term “second applied force” refers to the additional force applied beyond the yield strength of the metal causing a permanent deformation in the weld joint. The purpose of the second applied force is to stretch, compress, or alter the weld joint to ensure that it is uniformly shaped and has the desired mechanical properties. The types of second applied forces include post-weld stretching that helps to relieve residual stresses, or force application during welding to control the material flow, especially in processes such as forge welding or friction stir welding. The force is crucial in improving the final mechanical properties, such as tensile strength and ductility, of the welded joint. The main components involved in applying the second force include the force application equipment, such as but not limited to mechanical presses, hydraulic jacks, or custom-designed devices that exert high pressure or stretching forces on the welded material. The force is applied after the weld pool has solidified but before the material has fully cooled, or in some cases, after cooling, to achieve the desired final dimensions or mechanical characteristics. The second applied force works by overcoming the material's yield strength, causing it to deform plastically. The deformation corrects minor distortions, increases the strength of the weld, and relieves residual stresses developed during the welding process. In some advanced welding techniques, the force is applied during the cooling process to improve the grain structure of the material and enhance final properties, making the welded joint more resistant to fatigue or cracking. The second applied force plays a key role in achieving optimal weld quality and performance.
As used herein, the term “yield strength” refers to a stress level at which a material begins to deform plastically and will no longer return to its original shape once the applied stress is removed. The yield strength is a critical property in welding in determining the material's ability to withstand external forces without permanent deformation, ensuring the structural integrity of the weld and the joined materials. The types of yield strength that are typically considered in welding include static yield strength which is the material’s resistance to slow, applied stresses, and dynamic yield strength, which applies to situations where forces are applied rapidly or cyclically, as in fatigue testing. The components related to yield strength in welding include the base metal (the material being welded), the filler material (which contributes to the weld bead), and the weld joint. The working of yield strength in welding is observed when stress is applied to the welded joint, either during the welding process or after the weld has cooled. For effective welding, the applied forces, such as pre-weld heating or post-weld stretching, are typically controlled not to exceed the yield strength of the materials involved. When forces exceed this yield strength, permanent deformation occurs, which leads to issues such as distortion or cracking. The weld zone and heat-affected zone (HAZ) are particularly sensitive to yield strength, as the areas undergo thermal cycles that lower their yield strength. Therefore, controlling the yield strength is crucial for ensuring strong, reliable welds that perform well under stress without failure.
As used herein, the term “tensile strength” refers to the maximum stress a welded joint or material withstand while being stretched or pulled before breaking or fracturing. The tensile strength is a fundamental property that determines the strength and durability of a weld in resisting forces acting along the length of the joint. The two primary types of tensile strength considered in welding are ultimate tensile strength (UTS), which is the maximum stress a material handles before failure, and yield tensile strength, which is the stress level at which a material will start to undergo plastic deformation. Both types are important in evaluating the performance of the weld under different loading conditions. The key components involved in determining tensile strength in welding include the base metal (the material being welded), the filler material (used to create the weld bead), and the weld joint (the area where the two materials are fused). The tensile strength is measured by subjecting the welded joint to a tensile test, where the sample is pulled apart until it breaks. During the welding process, the heat applied causes changes in the microstructure of both the base material and the filler material, which affects the tensile strength. The working of tensile strength in welding involves ensuring that the weld joint has sufficient strength to resist external loads without fracturing. Factors such as proper welding technique, the use of compatible filler material, and post-weld treatments (such as stress-relieving or heat treatment) play a vital role in achieving a high tensile strength weld.
As used herein, the term “residual tensile strength” refers to the remaining tensile strength of a welded joint after the welding processes, including heat treatment, post-weld stress relief, or other mechanical force applications. The residual tensile strength is crucial in determining the durability and serviceability of a weld, especially in critical applications such as, the welded joint exposed to long-term tensile loads or stress cycles. The primary types of residual tensile strength are static residual tensile strength, which refers to the ability to resist tensile stress under static conditions, and fatigue residual tensile strength, which assesses the joint’s ability to resist repeated or cyclic loads. The components influencing residual tensile strength include the weld material (both base and filler materials), the heat-affected zone (HAZ), and the weld bead itself. After welding, the material undergoes residual stresses due to the uneven cooling and solidification of the weld, which affects the overall strength of the weld. The residual stresses are tensile or compressive and play a significant role in the material's performance under load. The working of residual tensile strength involves the measurement of tensile stress the welded joint will withstand after it has been subjected to the welding process, including any post-weld treatments. Further, to minimize the impact of residual stresses and enhance the residual tensile strength, techniques such as stress-relief heat treatment, post-weld stretching, or peening are applied. The above-mentioned methods help to reduce the probability of cracking or failure under load, ensuring the welded structure’s long-term reliability and resistance to fracture under stress.
In accordance with an aspect of the present disclosure, there is provided a method of improving weld quality between two metals selected from a first group and a second group, wherein a first metal is selected from the first group and a second metal is selected from the second group, the method comprising:
- pre-weld heating the first metal and the second metal;
- welding the first metal and the second metal to form at least one uniform weld joint; and
- stretching the at least one weld joint by applying a uniform force along a transverse axis of the weld joint.
Figure 1 describes a method 100 of improving weld quality between two metals selected from a first group and a second group. The method 100 starts at a step 102. At the step 102, the method 100 comprises a first metal is selected from the first group and a second metal is selected from the second group. At a step 104, the method 100 comprises pre-weld heating the first metal and the second metal. At a step 106, welding the first metal and the second metal to form at least one uniform weld joint. At a step 108, the method 100 comprises stretching the at least one weld joint by applying a uniform force along a transverse axis of the weld joint.
The above-mentioned method 100 aims to improve weld quality between two metals selected from two different groups, referred to as the first group and the second group. Specifically, the pre-heating of the metals is essential to raise the temperature of the base metals before welding, ensuring a more uniform weld joint and reducing the risk of cracking or other defects. Further, pre-heating reduces the temperature gradient between the welded area and the surrounding material, which leads to thermal stress. Additionally, pre-heating improves the flow of molten metal during welding, allowing for better fusion between the two different metals. Furthermore, after the welding process, applying a uniform force along a transverse axis of the weld joint to stretch the weld further enhances the mechanical properties of the weld. The stretching of the joint post-weld improves the refining of the microstructure of the weld zone, reducing potential internal stresses and improving the joint's ductility. The stretching contributes to a more uniform distribution of the material properties across the weld, enhancing the strength, toughness, and fatigue resistance of the weld. The combination of pre-weld heating, uniform welding, and post-weld stretching ensures a stronger, more reliable bond between the two metals, ultimately leading to better performance in applications requiring high-strength welds.
In an embodiment, the first group comprises at least one ferrous metal and the second group comprises at least one non-ferrous metal.
In an embodiment, the pre-weld heating of the first metal and the second metal is performed within a temperature range of 100°C and 400°C. The pre-weld heating is an important step in preparing the first metal and second metal for welding. Particularly, the metals are heated to a specific temperature range of 100°C to 400°C before the welding process. The minimum and maximum value of the temperature range is selected to optimize the behavior of the metals during the welding process. The heating is performed using methods such as, but not limited to, flame heating, induction heating, or furnace heating. Consequently, the first metal and the second metal achieve a uniform temperature before welding, thereby reducing the thermal shock, minimizing temperature gradients, and preventing issues such as cracking and/or warping. The heating ensures that both the first and second metals expand uniformly, allowing for better fusion at the weld interface. The dissimilar metals have different thermal expansion rates, and therefore, uniform heating reduces the heat input from welding. Further, the uniform heating allows for an even distribution of thermal energy across the metals leading to a more controlled welding process. Additionally, pre-heating enhances the metallurgical properties of the material, particularly for materials prone to brittleness at lower temperatures, by allowing the microstructure to stabilize before the welding process. Therefore, the heat helps to activate alloying elements to improve the weld's strength and integrity. Further, pre-heating prevents the formation of undesirable phases in the Heat-Affected Zone (HAZ) of the weld thereby improving overall joint quality. Specifically, as mentioned in Table 1 keyhole length is a critical factor in controlling the weld penetration. A deeper keyhole results in deeper penetration into the base material, which can improve the strength of the joint. However, excessive keyhole length leads to defects such as burn-through or excessive heat input. A well-controlled keyhole length helps in achieving consistent and high-quality welds. Further, the correct keyhole length ensures that the weld pool is adequately filled, and the weld bead has good bonding with minimal porosity, spatter, or distortion. Furthermore, managing the keyhole length helps control the size of the HAZ, which affects the material properties of the welded area.
Serial No. Current (Amps) Voltage (Volts) Welding Speed (mm/min) Temperature (°C) Max. Keyhole length (mm)
T1 300 15.1 to 15.5 60 No preheating 65
T2 300 15.1 to 15.5 90 No preheating 38
T3 300 15.1 to 15.5 90 250°C 82
T4 300 14.6 to 14.9 120 250°C 42
T5 300 15.1 to 15.5 120 300°C 86
T6 300 14.2 to 14.8 120 300°C 55
Table 1 Preheating and keyhole length
Referring to Table 1, an Electrolytic Tough Pitch copper (ETP Cu) strip of dimensions 100 x 50 x 6 mm is used for pre-heat testing. The ETP-cu strip material is an electrolytically refined, oxygen-containing copper with reliable electrical conductivity. Specifically, referring to Table 1, a serial number denotes the order of the testing with the ETP Cu under various conditions. Further, the supplied current value is kept constant, and voltage, welding speed, and temperature are varied to study the keyhole length. Consequently, the keyhole length obtained in the case T1 is 65 mm. However, the bead width variation increases due to the 60 mm/min welding speed. The variations in bead width are reduced with an increase in the welding speed of 90 mm/min. However, the keyhole length was reduced to 38 mm, in the case of the T2 condition. The condition of T3 (with preheating of 250°C) resulted in improved penetration compared to the condition of T2 (without preheating) at the same process parameters. Further, condition T5 (with preheating of 300°C) resulted in the most uniform weld bead geometry from the face and root side compared to all conditions mentioned. The pre-heat of 300 °C with T3 and T4 conditions, variations obtained in the bead width were 24 mm and 14 mm, with the keyhole length of 82 mm and 42 mm, respectively. T3 and T4 are performed using 90 mm/min and 120 mm/min welding speeds, respectively, along with preheating of 250°C. As a result, more heat was utilized to produce the keyhole mode during the bead-on-plate run. Further, the heat conducted along the specimen's width resulted in the highest variations in the bead width and the welding speed is slower, which served as an additional preheating source and subsequently resulted in the broader keyhole across the progressing length. In preheating conditions, heat conduction was possible along the width of the base metal that helps to stabilize the keyhole. Therefore, the experimental condition of T4 is executed with a higher welding speed of 120 mm/min to reduce the variation in preheating and the 120 mm/min welding speed with 300 amperes welding current is suitable for the bead width using lower heat input relative to the T3 condition. The results obtained explain that slower welding speed degrades the characteristics of the bead width. At the same time, higher welding speed keeping the preheating temperature constant, reduced the keyhole length. Therefore, the above table establishes that the preheating condition is essential to obtain precise keyhole conditions.
In an embodiment, the applied force comprises a first applied force and a second applied force. Specifically, the first applied force is introduced after the welding process to stretch the weld joint without causing permanent deformation. The magnitude of the first applied force is below the yield strength of the metals involved in the welding. The purpose of the first applied force is to remove any residual stresses created during welding maintain the weld's uniformity and prevent distortion, cracks, or other defects arising from the residual stresses. The first applied force is applied uniformly along the transverse axis of the weld joint to avoid introducing new stresses and to allow for a gradual adjustment in the metal structure. Further, the second applied force is greater than the yield strength of the metals involved, causing a plastic deformation of the welded joint. The second applied force is designed to further refine the weld’s characteristics by elongating the weld joint and testing the metal’s performance under higher stress. Further, the second applied force ensures that the weld will withstand extreme conditions by testing the metal’s limits. The resulting plastic deformation caused by this force enhances the ductility and toughness of the weld, making the weld joint more resistant to fractures and fatigue under high-stress conditions.
In an embodiment, the method 100 comprises applying the first applied force on the first metal and the second metal and wherein a magnitude of the first applied force is below a yield strength of the first metal and the second metal. The first applied force is applied after the welding process to stretch the weld joint along its transverse axis. The magnitude of the force is controlled and maintained below the yield strength of the first metal and second metal involved in the welding. The yield strength refers to the point at which the metal begins to permanently deform, so by ensuring that the force remains below this threshold, the applied force avoids any permanent deformation or damage to the metals. The force is applied uniformly across the weld joint, ensuring that the stretch occurs evenly, to relieve any internal stress built during the welding process. During the welding process, localized heating and cooling create thermal gradients that induce internal stress. The stress compromises the weld’s integrity, leading to defects such as cracking, warping, or premature failure. By applying a controlled force below the yield strength, the stresses are redistributed more evenly across the joint, which minimizes the risk of failure. Further, the controlled application of force is achieved using mechanical stretching devices or hydraulic presses, as the force is gradually increased to the desired level while monitoring the stress levels in the materials. By stretching the weld joint without surpassing the yield strength, the materials remain within their elastic region, to their original shape if the force is removed, thus preventing any permanent deformation.
In an embodiment, the method 100 comprises computing a first tensile strength based on the first applied force. The first tensile strength is computed based on the first applied force, which is applied to the welded joint. The first applied force, which is below the yield strength of the metals, is used to stretch the weld joint along its transverse axis. To compute the first tensile strength, the magnitude of this applied force is measured, and the stress-strain relationship of the welded joint is analysed. The tensile strength is determined by calculating the force per unit area (stress) that the welded joint can withstand before it begins to stretch significantly. The stress is achieved through a combination of force sensors, strain gauges, and stress analysis methods. The force is applied in a controlled and incremental manner to ensure the joint is stretched within the elastic range, which avoids permanent deformation or failure of the joint. The method to compute the tensile strength involves measuring the force required to stretch the weld joint to a particular extent. The applied force is measured, and using the known cross-sectional area of the weld, the tensile stress is calculated. The tensile strength is defined as the maximum amount of stress a material withstands while being stretched before breaking. The first tensile strength, based on the first applied force, reflects the weld's ability to resist stretching and failure under normal, non-deforming conditions. The calculation provides critical data for evaluating the weld joint's durability and resistance to deformation during regular use. Advantageously, computing the first tensile strength provides a quantitative measure of the weld joint’s capability to withstand stress, ensuring its performance is consistent with design specifications. The above-mentioned evaluation ensures that the welded joint handles the load without experiencing excessive deformation or failure. The changing welding parameters, such as heat input, preheating, or post-weld treatments, help to improve the overall strength of the joint. Additionally, computing the first tensile strength provides valuable data for quality control and assurance during the welding process. The computation ensures that the weld meets predefined standards for strength and performance, which is crucial in industries where the reliability of welded joints is critical. Further, the information on the first tensile strength also helps in optimizing the material selection and design process, allowing for the creation of more durable and efficient welds. Overall, the ability to compute and evaluate the first tensile strength helps improve the quality and longevity of welded structures, reducing the risk of weld failure and increasing the safety and reliability of the final product.
In an embodiment, the method 100 comprises applying the second applied force on the first metal and the second metal and wherein a magnitude of the second applied force is above the yield strength of the first metal and the second metal. Initially, the first applied force is applied below the yield strength of the metals, the second applied force is introduced to further stretch the weld joint. The magnitude of the second applied force is greater than the yield strength of both the first and second metals. The purpose of applying a force above the yield strength is to induce plastic deformation within the weld joint that goes beyond the elastic limit of the metals. The force is applied gradually and uniformly to ensure controlled deformation along the transverse axis of the weld joint. Subsequently, the metals experience permanent deformation, allowing the joint to settle into a more robust configuration. For the application of the force, techniques such as hydraulic presses, mechanical stretching devices, and other precision load application systems are employed. The force is monitored to ensure that the yield strength is exceeded without leading to fracture. The deformation process is measured through strain gauges or visual inspection to ensure joint performance under higher stress conditions. Additionally, the second applied force serves to refine the microstructure of the weld zone. The application of the second force enables the alignment and bonding of atoms at the interface between the two metals, improving the cohesion of the materials at the weld joint. Consequently, a more durable weld joint is created that withstands both static and dynamic loading conditions, reducing the likelihood of failure under extreme conditions. Further, the plastic deformation eliminates any microvoids or inconsistencies in the weld, strengthening the material at the joint interface. Specifically, the coarse grains are converted to fine grains thereby eliminating any microvoids.
In an embodiment, the method 100 comprises computing a second tensile strength based on the second applied force. As the second force is applied, plastic deformation is induced in the welded joint, causing permanent changes in the metal structure. For the computation of the second tensile strength, the magnitude of the second applied force is measured and the resulting deformation in the weld is assessed. The computation involves recording the force applied, measuring strain using strain gauges, and evaluating the metal behaviour beyond the elastic limit. Consequently, the second tensile strength is computed by dividing the maximum applied force (after the yield strength is exceeded) by the cross-sectional area of the weld joint. The above-mentioned computation provides an objective measure of the weld's behaviour under extreme stress, assessing the point at which the material enters the plastic region, and the amount of stress sustained before failure. Additionally, calculating the second tensile strength allows engineers to predict the behaviour of the weld joint under extreme conditions. In case the second tensile strength is sufficient to withstand the applied forces indicating that the weld is robust and performs better in challenging environments without failure. The ability to quantify the strength of the weld ensures that the design holds up reliably over time, preventing premature failures and increasing the overall safety of the welded structure. One key advantage of computing the second tensile strength is that the computation provides a direct measurement of the welded joint's capacity to withstand extreme forces. The above-mentioned optimization leads to more efficient use of materials and better performance, especially when working with dissimilar metals or when the weld joint is critical to the overall structural integrity.
In an exemplary embodiment, the method 100 comprises the welding of samples a 12 mm thick Cu, Al, and cast iron are selected as a base material, and the samples are cut to 100 mm x 50 mm x 12 mm size. The current is set at 325 amperes, which provides a sufficient power supply for welding tasks that require a medium to high heat input, allowing for deep penetration and strong welds. The voltage is set at 18.7 volts, with a constant current to maintain a stable arc and ensure consistent heat distribution along the workpiece. With a welding speed ranging from 90 to 120 mm per minute, the operator needs to maintain a steady pace to ensure a uniform weld bead and proper fusion of the materials. Preheating the workpiece to 140°C to 400°C is crucial to minimize thermal shock and prevent the formation of brittle microstructures, particularly when welding materials that are prone to cracking. The temperature range of 175°C to 400°C is the required temperature for the filler or base material before welding to achieve optimal mechanical properties. The arc gap is maintained at 1 to 2 mm, which is critical to ensuring a stable arc and preventing issues such as spatter, poor penetration, or arc instability. Further, a wide gap leads to an inconsistent arc and potential undercutting, while a narrow gap causes the electrode to short out or cause excessive heat buildup. The proper adjustment of the parameters contributes significantly to the overall quality of the weld, including penetration, bead shape, and the prevention of defects such as porosity or cracks. Further, the use of a gas mixture of 60% helium (He) and 40% argon (Ar) to enhance arc stability and provide higher heat input compared to pure argon. The helium component contributes to a more energetic arc, improving penetration, especially for thicker materials. The mixture is ideal for welding non-ferrous metals like aluminium, as it allows for better control of the molten pool and minimizes the risk of defects such as porosity. The gas flow rate is set between 15 to 20 litres per minute (l/min), which provides adequate shielding to protect the weld from contamination while maintaining efficient gas coverage, ensuring that the weld pool remains uncontaminated by atmospheric elements like oxygen and nitrogen. The wire feed rate, which is adjusted between 0.7 and 1.6 meters per minute (m/min), regulates the amount of filler material being fed into the weld pool. A consistent wire feed rate is crucial for maintaining uniform bead size and avoiding issues such as underfill or excess spatter. This range allows flexibility in terms of weld size and thickness, ensuring that the right amount of filler is deposited to meet the required weld strength and quality. The wire current, ranging from 50 to 100 Amperes, is directly correlated with the wire feed rate and the material being welded. It ensures that the filler material is melted properly to create a strong bond between the base materials. Higher currents generally produce more heat, leading to better penetration and faster weld speeds, while lower currents may be used for finer or more delicate welds. Finally, the filler wire voltage, which ranges between 0.2 to 0.7 volts, is an important parameter for controlling the arc behaviour and the heat transfer to the workpiece. A lower voltage helps achieve a more stable and focused arc, while a higher voltage can result in a wider, less controlled arc. This parameter is fine-tuned in conjunction with the wire feed rate and welding speed to ensure a consistent and high-quality weld with appropriate fusion and bead shape. Together, these parameters allow the welder to achieve precise, strong, and defect-free welds, particularly for materials requiring higher heat inputs or specialized shielding gases. Proper control over each aspect of the process helps to avoid common issues like undercutting, spatter, or weak welds, resulting in an efficient and reliable welding operation. The results obtained are mentioned below. The copper has a tensile strength of 221 MPa when it is not subjected to any mechanical deformation. The tensile strength indicates the inherent strength under normal conditions. After undergoing cold stretching, copper's tensile strength reduces to 205.5 MPa. The efficiency of copper after cold stretching is 92.98%, meaning that the copper retains 93% of the original tensile strength after cold stretching. The high efficiency implies that copper’s mechanical properties are minimally affected by deformation and the efficient weld joint is formed. Similarly, aluminum Tensile Strength (without cold stretching) is 310 MPa, making aluminum a relatively strong material compared to copper. After cold stretching, aluminum’s tensile strength decreases to 283.65 MPa. The reduction in strength is attributed to the material's relatively low strain-hardening capacity compared to other metals. The efficiency of aluminum after cold stretching is 91.5%, meaning the aluminum retains 91.5% of its original tensile strength. The Cast iron has a tensile strength of 180 MPa in its natural form, which is lower than both copper and aluminum.
Referring to figure 2, in accordance with an embodiment, there is described a comparison of the tensile strength of copper of the present disclosure with a reference document titled “Effects of Double-Pass Welding and Extrusion on Properties of Fiber Laser Welded 15 mm Thick T2 Copper Joints, 2016” by Ning et al is provided. A 12mm copper strip has a base tensile strength of 221Mpa without the cold stretching. Based on the reference document a tensile strength of 188Mpa is observed with cold stretching. The present disclosure provides a tensile strength of 205.5Mpa with cold stretching. Similarly, 15mm copper strip has a base tensile strength of 225Mpa. Based on the reference document, a tensile strength of 191Mpa is observed with cold stretching. The present disclosure provides a tensile strength of 207.27Mpa with cold stretching. Advantageously, the present disclosure demonstrates an improvement in tensile strength compared to the values observed in the reference document. For the 12mm copper strip, the tensile strength increases from 188 MPa to 205.5 MPa, and for the 15mm copper strip, the tensile strength increases from 191 MPa to 207.27 MPa. Further, the higher tensile strength after cold stretching ensures that the copper strips is able to withstand greater forces or loads without breaking. With improved tensile strength, manufacturers are able to use thinner or less material to achieve the same structural performance.
In an embodiment, the method 100 comprises comparing the first tensile strength and the second tensile strength and computing a residual tensile strength based on the comparison between the first tensile strength and the second tensile strength. Advantageously, computation of the residual tensile determines the metal’s behavior under varying levels of stress. The residual tensile strength is computed by analyzing the difference between the first tensile strength (reflecting the weld’s performance under normal, elastic conditions) and the second tensile strength (reflecting its performance under plastic deformation). Consequently, the residual tensile strength quantifies the strength lost or gained because of plastic deformation due to the second applied force. The residual tensile strength offers valuable insight into how much additional force the joint can withstand after undergoing plastic deformation, helping to determine whether the joint will perform well under varying operational conditions. The comparison provides critical information about the weld's resilience to fatigue and its ability to maintain structural integrity over time. Further, high residual tensile strength indicates that the weld joint will recover and withstand substantial deformation without failing and therefore achieve greater overall reliability. Conversely, a low residual tensile strength signals that the weld has been weakened by excessive deformation and will not perform well under long-term or high-stress conditions. Moreover, the computation of the residual tensile strength allows optimization of the welding process and better predicts the joint's performance over its service life. Further, based on the understanding of the effect of plastic deformation on the weld, adjustments are made to minimize any potential weakening that occurs during the stretching process.
Based on the above-mentioned embodiments, the present disclosure provides significant advantages such as (but not limited to) ensuring a stronger and a reliable bond between the two metals, optimization of the welding process, elimination of any micro voids or inconsistencies in the weld, strengthening the material at the joint interface and predicts the weld joint performance.
Modifications to embodiments and combinations of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, and “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings, and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
,CLAIMS:WE CLAIM:
1. A method (100) of improving weld quality between two metals selected from a first group and a second group, wherein a first metal is selected from the first group and a second metal is selected from the second group, the method comprising:
- pre-weld heating the first metal and the second metal;
- welding the first metal and the second metal to form at least one uniform weld joint; and
- stretching the at least one weld joint by applying a uniform force along a transverse axis of the weld joint.

2. The method (100) as claimed in claim 1, wherein the first group comprises at least one ferrous metal and the second group comprises at least one non-ferrous metal.

3. The method (100) as claimed in claim 1, wherein the pre-weld heating of the first metal and the second metal is performed within a temperature range of 100°C and 400°C.

4. The method (100) as claimed in claim 1, wherein the applied force comprises a first applied force and a second applied force.

5. The method (100) as claimed in claim 1, wherein the method comprises applying the first applied force on the first metal and the second metal and wherein a magnitude of the first applied force is below a yield strength of the first metal and the second metal.

6. The method (100) as claimed in claim 5, wherein the method comprises computing a first tensile strength based on the first applied force.

7. The method (100) as claimed in claim 1, wherein the method comprises applying the second applied force on the first metal and the second metal and wherein a magnitude of the second applied force is above the yield strength of the first metal and the second metal.

8. The method (100) as claimed in claim 7, wherein the method comprises computing a second tensile strength based on the second applied force.

9. The method (100) as claimed in claim 1, wherein the method comprises comparing the first tensile strength and the second tensile strength and computing a residual tensile strength based on the comparison between the first tensile strength and the second tensile strength.