Field of Invention
The present invention relates to weld surfacing of a material with similar /
dissimilar material in the form of powders, using the heat generated by
friction between surfaces in relative motion under pressure. More
particularly, the present invention relates to a friction stir surfacing
method to produce a compacted surface layer on a substrate using a
metallic powder material.
Background of the invention
Surfacing is a welding technique applied to industrial components
operating in service conditions involving corrosive medium or various
kinds of wear mechanisms or their combinations. Depending on the
intensity and severity of the service environments, the operating surfaces
are deposited with suitable materials to provide adequate service life to
the component. The thickness of deposit depends upon the service,
requirements.
Weld surfacing is a technology widely used for the manufacture of new
components including the repair and reclamation of serviced components.
For the purpose, several types of welding and spraying techniques are
employed. Several fusion welding techniques based on arc and/or gas
flame are generally preferred due to the associated lower cost and ease
of application. However, the arc welding techniques result in relatively
thicker weld deposits and often require multi-layer deposits due to the
higher level of dilution as consequent upon high-
energy dissipation. This leads to higher consumption of welding

consumables to achieve the required deposit surface properties. Spraying
techniques are suitable for thinner surfaced layers. However while fusion
welding produces strong metallurgical bonds, arc and gas based spraying
techniques using powder material for creating the coated surface produce
generally a mechanical bond between the surfaced layer and the
substrate. Hence, the surfaced layer may get disbonded with the impact
loading.
Patent No. EP0474455 discloses a process for surfacing of materials using
frictional heat generated by moving surfaces in contact under pressure.
The process involves the use of a rotating consumable in the form of a
rod. The rod is pressed against the material to be surfaced raising the
temperature of the rod material and / or the base metal to their plastic
temperature. As the rotating ool moves in a linear direction, the
plasticised material of the tool is transferred to the member being
surfaced and forms a deposited layer.
Patent No. U52005000424 describes a method for the formation of a
deposit of special characteristics using high velocity hot gas and powder
filler material. The powder particles heated to high temperature by the
high velocity hot gas impinge on the surface of the material on which the
deposit is being created.The impinging particles are mechanically locked
on to the surface and between themselves, resulting on a surface
deposited layer.

Patent No. GB 2222378 teaches a method of forming a hard facing along
an edge of a substrate comprises mechanically depositing by means of
rotatory friction surfacing a layer of relatively hard material along a
substrate, formed by a stack of sheets or blades clamped together. The
friction surfacing material is deposited along an edge of the stack, and
the resulting surfaced stack is split into individual sheets each having
along one edge a generally coplanar layer of adhered friction coating
material. The method may be used for forming a disposable knife blade
with a hard edge which can be ground sharp.
All the prior art methods however entails defects like porosity in the weld
deposit, material loss, lack of proper bonding, improper thickness and
bead appearance. Further, such processes require costly and Intricate
equipment.
Objects of the Invention
It is an object of the invention to propose a friction stir surfacing method
to produce a compacted surface layer on a substrate using a metallic
powder material, which eliminates the disadvantages of the prior art.
Another object of the invention is to propose a friction stir surfacing
method to produce a compacted surface layer on a substrate using a
metallic powder material, which makes use of powder fillers to produce
thin layers of deposits.

A further object of the invention is to propose a friction stir surfacing
method to produce a compacted surface layer on a substrate using a
metallic powder material, which is capable of producing a thin deposit
with good bonding over a wider area on a substrate using multiple
adjacent passes.
A still further object of the invention is to propose a friction stir surfacing
method to produce a compacted surface layer on a substrate using a
metallic powder material, which produces surface deposits with very low
dilution using powder materials.
A still another object of the invention is to propose a friction stir surfacing
method to produce a compacted surface layer on a substrate using a
metallic powder material, which is simple and economic.
Summary of the invention
Accordingly, there is provided a friction stir surfacing method to produce
a compacted surface layer on a substrate using a metallic powder
material, the method comprising providing a substrate having a base
material ; providing a rotatable tool having a base body and a profiled
tip configuration with a port to conduct a powder material
therethrough; erotating the tool and moving the rotating tool in a
direction vertical to the substrate ; characterized by comprising pressing
the rotating tool on the surface of the base material and conducting a

power material via the hole in a direction towards the part of the
profiled configuration for spreading the powder over the surface,
wherein the friction pressure generating heat to transform the base
including the metallic powder material to a plasticized condition which
produces a compacted surface deposit on the substrate. Thus, the
present application is based on friction stir welding process and not
friction welding. These two processes operate on different scientific
principles. The present invention adapts a metal powder which is fed
through a central hole of the body of a rotating tool and a port configured
on a tip-profile of the tool. Here, a combined action of the heat generated
on the surface of a substrate, and the powder material spreaded under
pressure on the plasticized surface, produces a compacted surface
deposit.
A friction stir surfacing method to produce a compacted surface layer on
a substrate using a metallic powder material, the method comprising
providing a substrate having a base material ; providing a rotatable tool
having a base body and a profiled tip configuration with a port to
conduct a powder material therethrough; erotating the tool and moving
the rotating tool in a direction vertical to the substrate ; characterized
by comprising pressing the rotating tool on the surface of the base

material and conducting a power material via the hole in a direction
towards the part of the profiled configuration for spreading the powder
over the surface, wherein the friction pressure generating heat to
transform the base including the metallic powder material to a plasticized
condition which produces a compacted surface deposit on the substrate.
Brief description of the accompanying drawings
Fig-1 a schematic diagram showing the details of a tool according to the
invention.
Fig-2 a schematic representation of the operating principle of the method
according to the Invention.
Description of a preferred embodiment of the invention
The present method involves use of a rotating tool of desired
configuration as
shown in Figure-1. The tool body (1) has a hole (2) along its axis. The tip
of the tool is profiled to enable transport and compaction of the powder
material to form the deposit. The powder passes through the central hole
(2) and a port (3) to a triangular profile (4). The rotating tool (1) initially
approaches the surface (6) in which the material is to be deposited.

Frictional heat is generated due the relative motion of the toot (1) under
pressure and the stationary base material (6). A powder material (5)
required to create the deposit is now fed through the
hole (2) at the center of the tool (1). The bottom of the tool (1) has
provisions for the discharge of the powder material (5) during the
operation of the process, to a friction zone. The frictional heat generated
softens the base material (6) and or the powder (5). The tool (1) enables
the powder material (5) to be spread across the width of the tool (1).
Simultaneously, the material is compressed, by a pressure generated in a
vertical direction (8) on the tool (1) including the profile (5) of the tool
(1) at its bottom side, into a compacted surface deposit (7). As the tool
(1) moves in the lateral direction (8), a uniformly deposited surface is
created. The deposit features can be controlled by controlling the feed
rate of the powder (5) through the tool (1) at the friction interface. The
principle of operation is shown in Fig.2.

We Claim:
1. A friction stir surfacing method to produce a compacted surface layer on a
substrate using a metallic powder material, the method comprising:
- providing a substrate (6) having a base material (6);
- providing a rotatable tool (1) having a base body (2) and a profiled tip
configuration (4) with a port (3) to conduct a powder material (5)
therethrough;
- rotating the tool (1) and moving the rotating tool (1) in a direction (8)
vertical to the substrate (6);
- characterized by comprising:
- pressing the rotating tool (I) on the surface of the base material (6) and
conducting a power material (5) via the hole (2) in a direction towards the
part (3) of the profiled configuration (4) for spreading the powder over
. the surface, wherein the friction pressure generating heat to transform
the base including the metalic powder material to a plasticised condition
which produces a compacted surface deposit (7) on the substrate.
2. The method as. claimed in claim 1, wherein the metallic powder material (5)
is a filler for creating the required deposit.

3. The method as claimed in claim 1 or 2, wherein the metallic powder
material (5) has the same or different characteristics as compared to that of
the base material (6).
4. The method as claimed in any of the preceding claims, wherein heat to
transform the base and/or powder material is generated due to the friction
between the relative motion of the rotating tool and the stationary surface
to be deposited.
5. The method as claimed in claim 1, wherein the rotatable tool has atleast
one exit port for discharge of the powder (5) from the central hole (2) to
the triangular shaped profiles (4).
6. The method as claimed in claim 1, wherein the plasticized material is
spreaded across the tool width by the rotation of the tool (1).
7. The method as claimed in claim 1, wherein one of the powder (5) or the
base material (6) or both (5,6) is plasticized depending upon their individual
plasticizing temperature.
8. The method as claimed in claim 7, wherein the spreaded powder (5) is
compacted by the compressive action and the triangular profiles (5) of the
tool (1) on the base material (6).

9. A friction stir surfacing method to produce a compacted surfaced layer on a
substrate using a metallic powder material as substantially described herein
with reference to the accompanying drawings.

ABSTRACT

TITLE: " A friction stir surfacing method to produce a compacted surface layer on
a substrate using a metallic powder material"
The invention relates to a friction stir surfacing method to produce a compacted
surface layer on a substrate using a metallic powder material, the method
comprising providing a substrate (6) having a base material (6); providing a
rotatable tool (1) having a base body (2) and a profiled tip configuration (4) with
a port (3) to conduct a powder material (5) therethrough; rotating the tool (1)
and moving the rotating tool (1) in a direction (8) vertical to the substrate (6);
pressing the rotating tool (1) on the surface of the base material (6) and
conducting a power material (5) via the hole (2) in a direction towards the part
(3) of the profiled configuration (4) for spreading the powder over the surface,
wherein the friction pressure generating heat to transform the base including the
metallic powder material to a plasticized condition which produces a compacted
surface deposit (7) on the substrate.