MECHANICAL TEST FOR NEW CONSUMABLES

[OLUBAJI]

Good day All,

I need some advice with mechanical tests to be carried out to test welding consumables(SMAW,SAW,GTAW,FCAW)..

The company i work for has decided to change the welding consumable used in fabrication due to financial reasons. But before they go ahead and make large purchase of the welding consumables. I have been told to use samples of the electrodes to weld test specimens. which will be mechanically tested to verify the mechanical properties of the consumable.......Please i need advise on what type of mechanical test will be suitable to check mechanical properties mostly strenght & performance under low temperature.......I know of tensile test, charpy test, bend & hardness......are these tests good enough? Am i to use all the tests mentioned above or just 1 or 2 of them? Are there other tests i need to carry out asides the ones i have mentioned above .....Thanks in anticipation for your response.


Best Regards,
Olubaji

 

[Goahead]

If you need an overview of test methods for evaluating welding joints, you can find them in chapter 6 of Volume 1 of the ninth edition of AWS Welding Handbook.
Financial reasons are the worst for substituting consumables. Probably looking for ways to reduce waste in production would give more tangible results.
Also your question is worded in so general terms that it is hard to give a sensible and comprehensive answer.
If you have specific WPS (welding procedure specifications) that were approved for certain requirements with suitable PQRs (process qualification records), you should simply try to repeat the approvals with the new consumables, to satisfy applicable Codes.
Sorry to say that the problem does not seem to me to be stated in a useful way.

http://www.welding-advisers.com/

 

[OLUBAJI]

Goahead,

Guess I missed out a few points while asking my Questions....I already have in place a WPS & a surpporting PQR which am using to carry out welding of the test specimens all I need to know is if the tests I mentioned are good enough or if there are other suggestions of tests outside the ones I mentioned to be carried out.....However Financial reasons is not a good reason to change consumables but if you agree with me the aim of every good & reputable buisness organisation is to render Quality services while making profit from the buisness, if the organisation has gone ahead to change consumables without considering quality it won't have put a measure in place to ensure they are using a good product i.e. Mechanical test being carried out. The organisation has a good deal with the consumable manufacturer.The manufacturer agreed to bear the cost of supplying us the consumable to be used for testing the consumables while the company I work for has agreed to bear the cost of welding the test specimens as well as a third party to witness welding & mechanical test of the specimens.


Regards,
Olubaji

 

[Goahead]

Olubaji,


Assuming that the consumable are defined according to an acceptable AWS Specification or equivalent, the manufacturer should be asked to provide proof that specification requirements are met.

Furthermore an approved Quality Assurance plan should be existing to prove that adequate manufacturing controls are in force to assure consistency of production quality.

Unfortunately I was unable to convey my doubt that the tests you plan to perform and the other ones you can think of will fail to provide a definitive proof that the proposed substitute consumables are indeed suitable for the purpose.

Indeed you could think of additional testing like fracture toughness, fatigue, creep testing (if applicable) etc., but you should specify also the requirement relative to the results, not only the types of test.

The purpose is to guarantee that the structures you are going to build will stand the service conditions with reasonable assurance of stability, functionality and continuous service for the design life time.

However "Predicting service performance on the basis of laboratory testing presents a complex problem because weld size, configuration and the environment as well as the types of loading to which weldments are subjected differ from structure to structure." (From the Welding Handbook above, pg 240)

If you have clear Code requirements, you can qualify your procedures using the new consumables against the requirements, (without reference to the results you have already with the original consumables) and consider you are covered once Code requirements are met.

If you don't have such Code requirements, in my opinion you cannot ever be sure that the substitute consumable are adequate.

http://www.welding-advisers.com/