Claims:1. A method for manufacturing lead free brass, the method comprising:
preparing a first master alloy by melting copper and a transition element at a first pre-determined temperature followed by rapid solidification under controlled atmosphere;
preparing a second master alloy by mixing a molten zinc along with flux into a molten copper at a second pre-determined temperature, followed by solidification;
melting, a predetermined proportion of the first master alloy and the second master alloy along with elemental copper at third predetermined temperature, followed solidification to obtain lead free brass alloy; and
subjecting, the lead-free brass alloy to a precipitation hardening to improve hardness of the lead-free brass alloy.

2. The method as claimed in claim 1, wherein the transition element is titanium (Ti), and the first master alloy is prepared by melting copper and titanium in a furnace.

3. The method as claimed in claim 1, wherein the first pre-determined temperature ranges from 1600 °C to 1800 °C.

4. The method as claimed in claim 1, wherein the rapid solidification of first master alloy is carried out in at least one of water-cooled copper hearth and steel wafer mould under controlled atmosphere to minimize oxidation of transition element.

5. The method as claimed in claim 1, wherein concentration of titanium in the first master alloy ranges from 5 wt.% to 35 wt.%.

6. The method as claimed in claim 1, wherein the second master alloy is Cu-Zn alloy with 50 wt. % Cu and 50 wt.% Zn.

7. The method as claimed in claim 1, wherein the second predetermined temperature is 950 °C to 1100 °C.

8. The method as claimed in claim 1, wherein the flux used in the preparation of the second master alloy is at least one of borax and charcoal.

9. The method as claimed in claim 1, wherein the third pre-determined temperature ranges from 950 °C to 1100 °C.

10. The method as claimed in claim 1, wherein melting of the first master alloy and the second master alloy along with elemental copper is carried out in a furnace under argon flow as cover gas with intermittent mechanical stirring.

11. The method as claimed in claim 1, wherein the lead-free brass alloy comprising a composition of:
Cu 57.5 wt.%-63.0 wt.%,
Zn 35.5 wt %-41.0 wt.%; and
Ti 0.5 wt.%-2.0 wt.%.

12. The method as claimed in claim 1, wherein the precipitation hardening of lead-free brass comprising:
heating, the lead-free brass alloy to a fourth pre-determined temperature
holding, the lead-free brass alloy at the fourth pre-determined temperature for a pre-set period of time;
cooling, the lead-free brass alloy to a fifth pre-determined temperature;
heating, the lead-free brass alloy to sixth pre-determined temperature; and
holding, the lead-free brass alloy at the sixth pre-determined temperature for a pre-set period of time to yield intermetallic precipitates.

13. The method as claimed in claim 12, wherein heating lead-free brass alloy to fourth pre-determined temperature is a solutionising process, and fourth pre-determined temperature ranges from 650-850 °C.

14. The method as claimed in claim 12, wherein holding time during solutionising process is 15-60 minutes to obtain homogenous microstructure thought the component.

15. The method as claimed in claim 12, wherein cooling of lead-free brass alloy to fifth pre-determined temperature is a quenching process, and fifth pre-determined temperature is room temperature.

16. The method as claimed in claim 12, wherein heating of lead-free brass alloy to a sixth pre-determined temperature is an ageing process, and sixth pre-determined temperature ranges from is 250-400 °C.

17. The method as claimed in claim 12, wherein holding time for ageing process is 20-120 minutes to yield intermetallic nanoscale precipitates distributed uniformly throughout the microstructure of lead-free brass alloy.
, Description:TECHNICAL FIELD
The present disclosure generally relates to a field of material science and metallurgy. Particularly, but not exclusively the present disclosure relates to a lead-free hard brass. Further, embodiments of the present disclosure disclose lead-free hard brass and a method for producing lead-free hard brass, which possess improved hardness and offers high resistance to defect such as dents, stains and scratches after heat treatment.
BACKGROUND OF THE DISCLOSURE
Brass (copper-zinc alloys) is widely used in numerous applications owing to its high strength and ductility. Brass is easily formable and has good electrical and thermal conductivity, it also possess good corrosion resistance and fatigue resistance properties. Brass can be classified into different types based on composition of zinc in the alloy, like a- brass which usually contains less than 37 wt.% of zinc, and aß brass which contains 37 to 45 wt. % of zinc in it. Lead is added in brass to improve the pressure tightness and machinability, with the high scrap value while turning, and no need for expensive electro plating. In recent years considering the adverse health effects of lead, stricter regulations have been enacted for the allowable lead content levels in products. This provides an impetus for the development of lead-free brass.
Generally, the lead-free brass is soft, and it may be prone to defect such as dents, stains and scratches attributed to the softness. The composition of lead-free brass used in industry ranges from 57.5-63 wt.% of Cu. The binary phase diagram of copper alloys indicates that transition elements such Cr, Fe, Ti, Zr, V, and Co could be served as candidate alloying elements for precipitation strengthening to develop high hard lead-free brass, because the solid solubility of these alloying elements shows sharply decreasing solid solubility in Cu with decreasing temperature. Copper-titanium (Cu-Ti) binary alloys have precipitation strengthening effects by spinoidal decomposition mechanism. The phase diagram (Figure 4) has five intermetallic phases namely Cu4Ti, Cu3Ti2, Cu4Ti3, CuTi, and CuTi2, indicates that Ti is the attractive alloying element for precipitation strengthening of copper alloy.

Constant research has been carried out in order to improve the hardness of lead-free brass alloy by doping Ti element. One such research work is described in a paper published by Shufeng Li et al. The paper describes that Cu40Zn-1.0 wt. % Ti Brass alloy which is prepared via powder metallurgy, spark plasma sintering and hot extrusion processes. However, the brass objects prepared via powder metallurgy, spark plasma sintering, and hot extrusion processes may not suitable for any further forming operations or precision machinery design works, as materials have already acquired an increased hardness which hinders the forming process. On the other hand, the hardness of brass objects manufactured by conventional forming process cannot be improved by powder metallurgy, spark plasm sintering and hot extrusion processes, since the structural damage may occur for the already precisely formed objects during these high temperature and high strain operations.

The present disclosure is directed to solve one or more limitation stated above or any other limitations associated with the prior arts.

SUMMARY OF THE DISCLOSURE

One or more drawbacks of available methods to manufacture lead-free hard brass are overcome, and additional advantages are provided through a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.

In a non-limiting embodiment, the present disclosure relates a method for manufacturing lead-free brass. The method involves preparation of a first master alloy by melting copper and a transition element at a first pre-determined temperature followed by rapid solidification under controlled atmosphere. Further, the method involves preparation of a second master alloy by mixing of a molten zinc along with flux into a molten copper at a second pre-determined temperature, followed by solidification. The lead-free brass is obtained by meting a predetermined proportion of the first master alloy and second master alloy along with elemental copper at third predetermined temperature in a furnace under argon atmosphere followed solidification to obtain lead-free brass alloy. This lead-free brass alloy is then subjected to precipitation hardening process in order to improve hardness.

In an embodiment, the transition element employed in the preparation is titanium (Ti), and the first master alloy is prepared by melting copper and titanium in a furnace.

In an embodiment, the first pre-determined temperature ranges from 1600 °C to 1800 °C.

In an embodiment, the rapid solidification of first master alloy is carried out in at least one of water-cooled copper hearth and steel wafer mould under controlled atmosphere to minimize the oxidation of transition element.

In an embodiment, the concentration of titanium in first master alloy ranges from 5 wt.% to 35 wt.%.

In an embodiment, the second master alloy is Cu-Zn alloy with 50 wt.% Cu and 50 wt.% Zn.

In an embodiment, the furnace employed in the preparation of Cu-Zn master alloy includes a medium frequency induction melting furnace.

In an embodiment, the second predetermined temperature is 950 °C-1100 °C.

In an embodiment, the flux used in the preparation of the second master alloy is at least one of borax and charcoal.

In an embodiment, third pre-determined temperature ranges from 950 °C to 1100 °C.

In an embodiment, melting a predetermined proportion of the first master alloy and second master alloy along with elemental copper is carried out in a furnace under argon flow as cover gas intermittent mechanical stirring.

In an embodiment, subjecting the lead-free brass alloy to a precipitation hardening occurs to improve hardness of the lead-free brass alloy.

In an embodiment, the lead-free brass alloy comprising a composition of: Cu 57.5 wt.%-63.0 wt.%, Zn 35.5 wt.%-41.0 wt.%; and Ti 0.5 wt.%-2.0 wt.%.

In an embodiment, the precipitation hardening of lead-free brass involves the heating the lead-free brass alloy to a fourth pre-determined temperature followed by holding at the fourth pre-determined temperature for a pre-set period of time. Later, the lead-free brass alloy is subjected for cooling to a fifth pre-determined temperature. The same lead-free brass is further heated to sixth pre-determined temperature and holded at sixth pre-determined for a pre-set period of time to yield intermetallic precipitates.

In an embodiment, the heating lead-free brass alloy to fourth pre-determined temperature is a solutionising process, and fourth pre-determined temperature ranges from 650-850 °C.

In an embodiment, the holding time during solutionising process is 15-60 minutes to obtain homogenous microstructure thought the component.

In an embodiment, the cooling of lead-free brass alloy to fifth pre-determined temperature is a quenching process, and fifth pre-determined temperature is room temperature.

In an embodiment, heating of lead-free brass alloy sixth pre-determined temperature is an ageing process, and sixth pre-determined temperature ranges from is 250-400 °C.

In an embodiment, holding time for ageing process is 20-120 minutes to yield intermetallic nanoscale precipitates distributed uniformly throughout the microstructure of lead-free brass alloy.

In an embodiment, intermetallic nanoscale precipitates distributed uniformly throughout the microstructure of lead-free brass alloy is Cu2TiZn.

In another embodiment, the present disclosure relates to a lead-free brass produced by the said method, wherein the said manufactured lead-free brass possess improved hardness properties.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The novel features and characteristics of the disclosure are set forth in the appended description. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Figure 1 is a flow chart showing the steps involved in the process of manufacturing lead-free brass, in accordance with an embodiment of the present disclosure.
Figure 2 illustrates an equilibrium phase diagram of Cu and Zn, in accordance with an embodiment of the present disclosure
Figure 3 illustrates optical micrograph of brass (a) as cast depicting Widmanstätten structure (b), equilibrium a+ß after annealing, in accordance with an embodiment of the present disclosure.
Figure 4 illustrates the Cu-Ti equilibrium diagram (right side is Cu rich) shows a large number of intermetallic phases present in the equilibrium diagram, in accordance with an embodiment of the present disclosure.
Figure 5 illustrates optical micrograph of (a) Cu-8.5wt.% Ti and (b) Cu-30wt.% Ti master alloy, in accordance with an embodiment of the present disclosure.
Figure 6 illustrates optical micrograph of (a) 59Cu-41Zn Brass (b) 63Cu-37Zn Brass without Ti addition, in accordance with an embodiment of the present disclosure.
Figure 7 illustrates optical micrograph of 61Cu-39Zn Brass with 0.5 wt.% Ti (a) as-casted and (b) solutionised, in accordance with an embodiment of the present disclosure.
Figure 8 illustrates optical micrograph of 63Cu-37Zn Brass with 0.5wt.% Ti (a) as-casted and (b) solutionised, in accordance with an embodiment of the present disclosure.
Figure 9 illustrates a graphical representation of aging kinetics of various brass compositions with 0.5wt.% Ti and 1.0wt.% Ti, in accordance with an embodiment of the present disclosure.
Figure 10 illustrates TEM bright field image and corresponding SAED pattern confirming the presence of Cu2TiZn intermetallic precipitates in the lead-free bass, in accordance with an embodiment of the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF THE DISCLOSURE

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the description of the disclosure. It should also be realized by those skilled in the art that such equivalent methods do not depart from the scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a method that comprises a list of acts does not include only those acts but may include other acts not expressly listed or inherent to such method. In other words, one or more acts in a method proceeded by “comprises… a” does not, without more constraints, preclude the existence of other acts or additional acts in the method.

The present disclosure disclose a method for manufacturing lead free brass. The method includes various process, like preparation of first master alloy by melting copper and a transition element is carried out at a first pre-determined temperature followed by rapid solidification. Further, a second master alloy is prepared by mixing a molten zinc along with flux into a molten copper at a second pre-determined temperature, followed by solidification. Later, a predetermined proportion of the first master alloy and the second master alloy along with elemental copper may be melted at a third predetermined temperature, followed solidification to obtain lead free brass alloy. Intermittent heat treatments such as but not limited to annealing, water quenching or air cooling are performed on the lead-free brass.

The lead-free brass currently possesses an average hardness of 85 to 90 HV in Vickers hardness scale. It can be strengthened by precipitating strengthening method. Precipitation hardening, also known as age hardening is a type of heat treatment that may be used to impart high strength and improve the hardness of metals and their alloy. Precipitation hardening mainly includes following steps:

Solutinising or solution annealing: In this step, an alloy may be heated to a temperature T1, between the solvus and solidus temperatures and soaked until all of the solute dissolves to form a uniform solid-solution structure. This step mainly aims in getting homogenous single-phase microstructure.

Quenching: Quenching is a simple rapid cooling process to room temperature to form a non-equilibrium supersaturated solid solution to prevent diffusion and the accompanying formation of any second phase. During quenching, the solute may not immediately be able to diffuse out of a phase and the solid solution after quenching may be supersaturated and metastable. Typical quenching agents in precipitation hardening are water, brine, oil etc.

Ageing: During ageing process, the supersaturated solid solution may be heated to an intermediate temperature within the two-phase region as at this temperature diffusion rates become appreciable. The precipitates of the second phase form as finely dispersed particles in the matrix of primary phase.

In the method of the present disclosure, the precipitation hardening of lead-free brass is carried out by heating the lead-free brass alloy to a fourth pre-determined temperature, holding, the lead-free brass alloy at the fourth pre-determined temperature for a pre-set period of time, and then cooling, the lead-free brass alloy to a fifth pre-determined temperature. Further, the method includes heating, the lead-free brass alloy to sixth pre-determined temperature and holding, the lead-free brass alloy at the sixth pre-determined temperature for a pre-set period of time to yield intermetallic precipitates.

The lead-free brass alloy of composition 63Cu-37Zn lies in phase diagram (Figure 2) where intermediate phase of a+ß exists at room temperature and is therefore called as dual phase brass. The microstructure of the as cast lead-free brass shows the Widmanstätten structure (Figure 3a) where a plates are precipitated on ß matrix. After annealing the cast alloy show the equilibrium microstructure (Figure 3b). The lead-free brass currently possess an average harness of 85-90 HV in Vickers hardness scale. The low hardness of this lead-free brass has been improved by precipitation strengthening method with the addition of titanium.

The following paragraphs clearly explains the detailed steps or process involved in manufacturing of lead-free brass:
The first process of the method is preparation of first master alloy which is prepared by melting copper and titanium. In an embodiment, concentration of titanium in first master alloy ranges from 5 wt.% to 35 wt.%. The first master alloy of Cu-Ti may be synthesized in a vacuum arc melting or vacuum induction melting furnace. Since Ti is highly reactive with oxygen at high temperatures, a controlled atmosphere may be essential for melting. Melting of Cu-Ti master alloy may be done at 1600 °C to 1800 °C and rapidly solidified in a water copper hearth or steel wafer mould under controlled atmosphere. Figures 5a and 5b show the optical micrograph of Cu-8 wt.% Ti and Cu-35 wt. Ti master alloys. The microstructure shows the presence of Cu4Ti intermetallics in Cu matrix in the case of Cu-8 wt.% Ti (Figure 5a) and needle shaped Cu2Ti intermetallics in Cu-30 wt.% Ti master alloy matrix (Figure 5b). These precipitates are dissolved in the melt and releases Ti during further melting with Cu-Zn alloy.

The method further includes step of preparing a second master alloy, which is prepared by mixing molten zinc to molten copper. In an embodiment, the master alloy of 50Cu-50Zn is synthesized in the medium frequency induction melting furnace. Initially, copper is melted at 950 °C to 1100 °C in a graphite crucible and the zinc may be added to the molten copper. In order to minimize the loss of zinc, flux material such as borox or charcol is sprinkled on the molten zinc before it is being added to the molten copper in the crucible. The process has been optimized to reduce the zinc loss through evaporation.

In order to prepare the desired lead-free brass composition, first master alloy of with 50 wt. % Cu and 50 wt.% Zn and the second master alloy are melted along with excess amount of elemental copper in the induction furnace under argon flow as cover gas. The melt may be mechanically stirred intermittently to ensure homogenous mixing of Ti in molten bath. The melt may be casted after 5 minutes in steel plate mould. The melting experiments may be conducted with various concentrations of Cu, Zn and Ti in order to optimize the composition and the process parameters. The details of the process optimization are tabulated in table 1. Melting is carefully carried out at lower temperature in order to avoid zinc evaporation. As-cast hard brass samples are sliced using abrasive cutting machine for metallographic sample preparation in order to carry out optical microscopy image analysis.

S/no. Code Composition
(wt.%) Melting temperature (°C)
1 BST001 61Cu-38Zn-1Ti 1100
2 BST002 61Cu-38Zn-1Ti 1100
3 BST003 58Cu-41Zn-1Ti 950
4 BST004 57.5Cu-41Zn-1.5Ti 950
5 BST005 58Cu-41Zn-1Ti 950
6 BST006 58.5Cu-41-0.5Ti 950
7 BST007 61Cu-38.5Zn-0.5Ti 950
8 BST008 63Cu-36.5Zn-0.5Ti 950
9 BST009 63Cu-36Zn-1Ti 950
10 BST010 61Cu-38.5Zn-0.5Ti 950
11 BST011 61Cu-38Zn-1Ti 950
12 BST012 61Cu-37.5Zn-1.5Ti 950
13 BST013 62Cu-37.5Zn-0.5Ti 950
14 BST014 62Cu-37Zn-1Ti 950
15 BST015 62Cu-36.5Zn-1.5Ti 950
16 BST016 63Cu-36.5Zn-0.5Ti 950
17 BST017 63Cu-36Zn-1Ti 950
18 BST018 63Cu-35.5Zn-1.5Ti 950
Table 1: Experimental trials of the melting and casting of the Ti containing Brass

Table1 indicates the optimization process for the manufacturing of lead-free brass alloy. Composition of Cu in lead-free brass is varied from 57.5 wt.%-63.0 wt.%, Zn is varied from 35.5 wt. %-41.0 wt.%; and Ti is varied from 0.5 wt.%-2.0 wt.%. Manufacturing process is performed in a temperature window of 950 °C -1110 °C inside the induction furnace under argon flow as cover gas. Fine tuning of the process parameters may be carried out to minimize oxidation of titanium element, evaporation of zinc element and to get defect free microstructures.

Precise final composition of first master alloys, second master alloys and lead-free brass with Ti (as tabulated in table 1) is measured by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).

Figures 6a and 6b shows optical micrograph of the as-cast, 59Cu-41Zn brass and 63Cu-37Zn brass without Ti. The former exhibits Widmanstätten structure of ? in the matrix ß and the later shows complete ?-brass phase. Addition of 0.5 wt.% may not create much influence on the grain structure of 61Cu-39Zn brass, as it also exhibits Widmanstätten structure of ? in the matrix ß (Figure 7a). The annealing of the sample at 750 oC for 60 minutes followed by air-cooling develops the equi-axed grain with annealing twins in the grain boundary (Figure 7b). Similar microstructures are evident in the case of 63Cu-37Zn brass with 0.5wt.% of Ti as well (Figure 8a and 8b).
In an embodiment, during forming process, the repeated annealing may be carried out to relieve the stress, and also decreases the hardness of the alloy for smooth workability. Precipitation strengthening of the lead-free brass containing titanium (Ti) has been carried out to increase the hardness to large extent by adopting either tempering treatment T6 (Solutionising and age hardening) or T8 (Solutionising – cold-working – age hardening). The presence of Ti increases the work hardening rate in comparison to the regular brass containing no Ti.

During precipitation hardening process, solutionising heat treatment may preformed to get a homogenous microstructure though of the components. During solutionising process, lead-free brass alloy is heated to fourth pre-determined temperature and fourth pre-determined temperature ranges from 650-850 °C and holding time during solutionising process may be 15-60 minutes to obtain homogenous microstructure thought the component. After solutionising process cooling of lead-free brass alloy to fifth pre-determined temperature is a quenching process and fifth pre-determined temperature is room temperature. The sample may be rapidly quenched to room temperature via any one of the quenching media such as brine solution, ice cold water, oils etc. Quenching is mainly carried out in order to get supersaturated Ti in Cu-Zn matrix. After quenching, heating of lead-free brass alloy to a sixth pre-determined temperature is an ageing process, and sixth pre-determined temperature ranges from 250-400 °C. After quenching, the samples are age hardened at temperature 250 to 400 °C well below the solutionising temperature for a time of 20-120 minutes followed by air cooling. This heat treatment causes the excess solute Ti to form nano-sized “Cu2TiZn” precipitates in the Cu-Zn matrix which contribute for the improved hardness in the sample by hindering the dislocation movement.

The process of solutionising/quenching and age hardening of 58Cu-42Zn brass alloy with 0.5 and 1.0 wt.% Ti addition & 61Cu-39Zn brass with 0.5 and 1.0 wt.% Ti have been carried out. The solutionising is carried out at 800 °C for 60 minutes followed by rapid quenching in ice brine water. The age hardening is done at 350 °C for 5 hours in order to study the kinetics. Figure 9 illustrates the aging kinetics of the lead-free brass samples for a time period of 5 hours at 350 °C. For all brass samples, it is observed that peak hardness is obtained after one hour of age hardening for irrespective of Cu, Zn and Ti concentration. It is mainly due to the fact that after one hour of age hardening, the intermetallics particles are grown to a right size so that they could effectively hinder the dislocation motion by their pinning effect. The hardness gradually drops down beyond 1 hour of aging hardening time mainly due to overgrown large intermetallic particles become insufficient to block the dislocations in many regions and pinning effect drastically decreases with overly grown intermetallic particles.

Exemplary characterization results:

Hardness measurements:
Hardness measurements for various lead-free brass containing Ti (as tabulated in Table 1) are carried out after casting, solutionising and age hardening (1 hour) processes and for each sample, the hardness measurements are carried out in Vickers’s hardness testing method e at 300 g load. 58Cu41Zn1Ti lead-free brass alloy exhibits improved hardness of 194.84 HV comparison with 85-90 HV for lead-free brass containing no Ti.

Sl/no. Alloy Hardness After casting (H3V) Hardness after Solutionising
Hardness after age hardening (1 hour) (H3V)
1 58.5Cu41Zn0.5Ti 120.1 HV 101.5 HV 179.84 HV
2 58Cu41Zn1Ti 121.5 HV 95.7 HV 194.84 HV
3 61Cu38.5Zn0.5Ti 98.3 HV 88.83 HV 160.1 HV
4 61Cu38Zn1Ti 104.2 HV 90.67 HV 181.6 HV
Table 2: The hardness values for the as-cast, solutionised and age hardened lead-free brass with Ti
Figure 10a depicts the Transition Electron Microscopy (TEM) bright field image of 58Cu-42Zn brass alloy with 1.0 wt.% Ti owing denser precipitations of nano sized Cu2TiZn in the Cu-Zn matrix at 1hour ageing process (i.e. peak aging time). Figure 10b depicts the Selected Area Electron Diffraction (SAED) analysis pattern for lead-free brass containing Ti and confirms the presence of nano sized Cu2TiZn intermetallic precipitates in lead-free brass alloy.

In an exemplary embodiment, the Lead-free brass may be used in horology industry for manufacturing case of watches. To produce the watch case, the lead-free brass may be subjected to at least one of hot forming or cold forming process to form shapes such as but not limiting to sheets. Lead-free brass sheets are subjected to piercing and blanking operation to prepare objects such as but not limited to watch cases. Intermittent heat treatments such as but not limited to annealing, water quenching or air cooling are provided to formed objects. Solutionising process is carried at 700-800 °C for 60 minutes. After solutioning process, the lead-free brass is quenched to water. Later, age-hardening process is carried out at 200-400 °C for 60 minutes followed by air cooling to obtain improved hardness. Finishing operations such as but not limited to polishing and plating are carried out to obtain the final finished objects.

Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.