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FIELD OF THE INVENTION
The present invention relates to development of a corrosion fatigue testing device and method of carrying out corrosion fatigue experiments on weldments of metallic materials. More particularly, the invention relates to a means which can be mounted on the standard testing systems to ensure submerging of the weldment in corrosive medium.
BACKGROUND OF THE INVENTION AND DIFFICULTIES OF PRIOR ARTS
Fatigue is a damage mechanism which accounts for about 90% of failure of engineering structures. In the case of weldments, the fatigue life will be much shorter due to the inherent limitations of welding. When the corrosive medium is present near the weldment and combined with fatigue loading, the fatigue life comes down drastically. This is due to the fact that the corroded surface of the

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outer layers of the weldment provide excellent points for the crack initiation. In addition during the crack propagation phase, the presence of corrosive medium accelerates the rate of crack propagation. It is therefore an outstanding demand of industries to search for a compatible and reliable testing means to measure corrosion fatigue life of weld specimens.
Japanese Patent JP 2004077230 deals with the development of a facility for the corrosion fatigue test on bending specimens. The corrosive medium is impregnated in a sponge member and the corrosive medium is discharge on the surface of the specimen by depressing the sponge member.
Publication No: JP 04-190139, titled "Corrosion Apparatus For Fatigue Test", deals with the development of a corrosion apparatus for fatigue test. The corrosive medium flows from a thermostatic tank during the test.
Publication No: JP 11-166885, titled "High-Temperature Corrosion Fatigue Testing Method And Device Therefore", deals with corrosion fatigue testing at high temperature in which the corrosive medium is sprayed intermittently on the specimen during testing.

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Publication No: JP 09-166539, titled "Corrosion Fatigue Damage Detecting Device", deals with a device for detecting the fatigue damage under corrosive operating conditions.
US 20040023601, titled "Method and device for obtaining shaped test-pieces of steel as required in tensile under corrosion fatigue tests", deals with the method of preparing a corrosion fatigue test specimen which rotates about its own axis.
None of the said prior references have met the essential requirement of carrying out corrosion fatigue measurement on maintaining the specimen under immersed conditions during the entire duration of testing.
The proposed invention is aimed to solve the aforesaid difficulties of prior art by a set up device to carry on corrosion fatigue testing under immersed condition.
DESCRIPTION OF THE INVENTION
One object of the invention is to propose an in situ device which can be used for the corrosive fatigue testing of welded specimens using a standard testing machine.

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Another object of the invention is to propose a device with means for mounting the standard fatigue test specimen.
An yet another object of the invention is to propose a device which can be used for filing corrosive medium which will immerse the specimen during the testing operation.
A still another object of the invention is to propose a device which after manufacture can be mounted on the standard testing machine.
A still further object of the invention is to enable the monitoring of the crack growth in the specimen from the initiation upto final failure of the specimen.
These and other objects and advantages of the invention will be apparent from the ensuing description.
According to the invention there is provided a device for corrosion fatigue testing on weldments of metallic materials comprising: a mounted split steel base plate at the bottom of a test specimen containing a weld, a bottom slotted plastic

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container placed on the base plate surrounding the specimen, a slotted rubber / synthetic rubber washer rest on the bottom of the pastic container, a slotted top steel plate placed on the top of the washer, the slit steel base plate, the plastic container, the washer and the top steel plate inserted through their slotted holes on the specimen being tightly fastened by bolts, the said test specimen with the set up device is then tested for corrosion fatigue measurement on clamping the specimen with top and bottom jaw of the testing machine on pouring corrosive medium into the plastic container on complete immersion of the weld with the corrosive medium.
The invention also relates to a method of forming a device for corrosion fatigue testing on weldments of metallic materials comprising the steps of: mounting a split steel base plate at the bottom of the specimen containing a weld; inserting a bottom slotted plastic container and placing it on the base plate; inserting a slotted rubber / synthetic rubber washer and placing it at the bottom of the container; inserting a slotted top steel plate and placing it on top of the washer; tightly fastening the split base plate, the plastic container, the washer and the top steel plate by bolts; the said test specimen with the set up device is then

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tested for corrosion fatigue measurement on clamping the specimen with top and bottom jaw of the testing machine on pouring corrosive medium into the plastic container on complete immersion of the weld with the corrosive medium.
The proposed device is mounted surrounding a specimen to be tested for measurement of corrosion fatigue when the welded test specimen is maintained under load through grips at its ends by a testing machine.
The set up of the device is formed by split steel plate according to the cross section of the specimen and mounting the said plate firmly on the specimen at its bottom. Placing a bottom plastic container for housing a corrosive medium on the steel plate. A rubber or synthetic rubber washer is placed on the bottom of the plastic container.
A top steel plate is then placed on the top of the washer and the said bottom and top plates and the bottom of the container are tightly fastened with bolts to ensure a secured seal to prevent any leakage of the corrosion medium from the plastic container.

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The proposed invention will be better understood from the following description with reference to the accompanying drawings in which
Figure 1 shows schematically an embodiment of the device according to the invention.
Figure 2 shows a split steel base plate with a slot.
Figure 3 shows a rubber washer with a slot for inserting the specimen.
Figure 4 shows a top steel plate with a slot for inserting the specimen.
The device is mounted on the fatigue test specimen (3) containing the weld (4) such that when the corrosive medium (9) is filled in the container (8), the corrosive medium (9) covers the weld (4) fully and there is a minimum of two inches of the corrosive medium (9) above the weld (4). In the figures a split steel plate base (5) contains a slot (11) on which the specimen (3) is held and on which the device is mounted. A plastic container (8) containing a slot is inserted over the specimen (3) by sleeving through the specimen before it is gripped in a

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testing machine. A rubber washer (6) containing a slot is inserted surrounding the specimen (3) similarly so that it rests on the bottom of the plastic container (8). Likewise a steel plate (7) which also contains a slot is inserted surrounding the specimen (3) and placed on the top of the rubber washer (6). The bottom split steel plate (5), the bottom of the plastic container (8), the rubber washer (6) and the top steel plate (7) are bolted tightly as shown in the figure 1 by bolts (11). To avoid any leakage of the corrosive medium during the entire duration of the fatigue testing, suitable adhesives are applied circumferentially at the contact face of the top steel plate of the container and the contact surface of the specimen to fix the arrangement securely. The specimen (3) is then clamped in the top jaw (1) and bottom jaw (2) of the testing machine. After clamping the specimen, corrosive medium (9) is poured into the plastic container (8) till the level of the medium is at least two inches above the weld (4) in the specimen (3). The corrosion fatigue test is carried out in this fashion.
The invention as described and illustrated herein should not be read and construed in a restrictive manner as various adaptations, alterations and modifications are possible within the scope and limit of the defined claims as appended.

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WE CLAIM
1. A device for corrosion fatigue testing on weldments of metallic materials comprising:
- a mounted split steel base plate (5) at the bottom of a test
specimen (3) containing a weld (4);
- a bottom slotted plastic container (2) placed on the base plate (5)
surrounding the specimen;
- a slotted rubber / synthetic rubber washer (6) rest on the bottom
of the pastic container (8);
- a slotted top steel plate (7) placed on the top of the washer (6);
- the split steel base plate (5), the plastic container (8), the washer
(6) and the top steel plate (7) inserted through their slotted holes
on the specimen being tightly fastened by bolts (10);
- the said test specimen with the set up device is then tested for
corrosion fatigue measurement on clamping the specimen with top
and bottom jaw (1 and 2) of the testing machine on pouring
corrosive medium (9) into the plastic container on complete
immersion of the weld (4) with the corrosive medium.

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2. The device as claimed in claim 1, wherein the said weld (4) in the
specimen is maintained immersed under the medium upto two inches
above the weld.
3. The device as claimed in claim 1, wherein the split steel base plate (5)
supports the whole device including the plastic container (8) on firm
attachment of the splitted halves of base plate over the specimen under
test registered in a slot (11) of the base plate during the entire duration
of testing.
4. The device as claimed in the preceeding claims, wherein the said device
is ensured from any leakage of corrosive medium on applying a suitable
adhesive circumferentially at the contact surface of the top steel plate (7)
with the container and the contact surface of the specimen.
5. The device as claimed in the preceeding claims, wherein the said device
set with the testing machine is used for monitoring of crack initiation and
crack propagation of the test specimen during the corrosion fatigue
testing till final failure of the specimen.

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6. A method of forming a device for corrosion fatigue testing on weldments of metallic materials comprising the steps of:
- mounting a split steel base plate at the bottom of the specimen
containing a weld;
- inserting a bottom slotted plastic container and placing it on the
base plate;
- inserting a slotted rubber / synthetic rubber washer and placing it
at the bottom of the container;
- inserting a slotted top steel plate and placing it on top of the
washer;
- tightly fastening the split base plate, the plastic container, the
washer and the top steel plate by bolts;
- the said test specimen with the set up device is then tested for
corrosion fatigue measurement on clamping the specimen with top
and bottom jaw of the testing machine on pouring corrosive
medium into the plastic container on complete immersion of the
weld with the corrosive medium.

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7. A method of forming a device as damned in claim 6, wherein the plastic
container is ensured from any leakage of corrosive medium on applying a
suitable adhesive circumferentially at the contact surface of the top steel
plate with the container and the contact surface of the specimen.
8. A method of forming a device as claimed in claim 6, wherein the method
is used for monitoring of crack initiation and crack propagation of the test
specimen during the corrosion fatigue testing till final failure of the
specimen.
9. A device for corrosion fatigue testing on weldments of metallic materials
as herein described.
10. A method of forming a device for corrosion fatigue testing on weldment
of metallic materials as herein described.

This invention relates to a device and a method of forming the device for corrosion fatigue testing on weldments of metallic materials comprising: a mounted split steel base plate (5) at the bottom of a test specimen (3) containing a weld (4); a bottom slotted plastic container (2) placed on the base plate (5) surrounding the specimen; a slotted rubber / synthetic rubber washer (6) rest on the bottom of the pastic container (8), a slotted top steel plate (7) placed on the top of the washer (6); the slit steel base plate (5), the plastic container (8), the washer (6) and the top steel plate (7) inserted through their slotted holes on the specimen being tightly fastened by bolts (10); the said test specimen with the set up device is then tested for corrosion fatigue measurement on clamping the specimen with top and bottom jaw (1 and 2) of the testing machine on pouring corrosive medium (9) into the plastic container on complete immersion of the weld (4) with the corrosive medium.