Hi,
I have some TIG welded stainless steel 304L samples that I'm looking for erasing residual stress with. The goal is to remove both compressive and tensile residual stress while keeping the microstructural change as minimal as possible. The base material was cold rolled and pickled. I did some literature review and search for a suitable annealing process for the stress relief, but got many different recommendations. I want to ask if you can help recommend/explain which one of these will best serve my need?
1. 1080C for 1 hour, quenching
2. 1080C for 1 hour, slow cooling
3. 400C for 0.5-2 hours, slow cooling
4. 900C for 1 hour, quenching
5. 900C for 1 hour, slow cooling
Thank you very much for your precious input and help!
Based on my own 11 years of experience in the field of oil and gas industry we never allow PWHT (Post weld Heat Treatment) to be done on the weldments or HAZ area of austenitic stainless steels because of the probability of sensitization and chromium depletion which would result in intergranular corrosion.
For more information you can take a look at the following link and their recommendations in this regard, it belongs to TWI which is very famous in the field of welding:
https://www.twi-global.com/technical-knowledge/faqs/faq-is-post-weld-heat-treatment-normally-required-when-welding-chromium-nickel-austenitic-stainless-steels
Dear Haozheng Qu you may find what you need in the following link
http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/Stress_Relieving%20Heat%20Treatment%20for%20Austenitic%20Stainless%20Steel%20-%20Stainless%20Steel%20Tube.pdf
Please refer to page 736 of the Heat Treater's Guide-Practices and Procedures for Irons Steels, Second Edition, Harry Chandler (Editor), ASM International.
Mehdi Gharagozloo Dear Mr. Gharagozloo,
Thank you very much for your help!
Abdulaziz Albannai Dear Mr. Albannai,
Thank you very much for your help!
Dear Haozheng Qu ,
For dimensional stability, a fairly low temperature treatment at around 400°C, giving partial stress relief, may be sufficient. For SCC resistance it may be appropriate to use a much higher temperature treatment, at around 1000°C, so that most of the internal stress is relieved. Heavy sections in certain stainless steels (e.g. stabilised grades such as type 347) operating in the creep temperature range can suffer reheat cracking, and stress relief (>950°C) is the only guaranteed method of avoiding this problem.
in practice it is difficult to go for PWHT especially in-situ applications, however if leave the weld, result may not vary much more . To the extent, air blow, with a fan may be used to cool down quickly between 850 to 450 deg C to avoid sensitization.
Emil Hristov Yankov Dear Prof. Yankov,
Thank you very much for your input! For the 400C partial and 1000C solution annealing, would you recommend quenching or furnace cooling afterwards? I have tried both, but the XRD still shows there are residual stress on the surface afterwards. Do I need to polish away the oxidized surface after annealing?
Best,
Haozheng
Nelaturi V Raghavaiah Dear Dr. Raghavaiah,
Thank you very much for your input!
Hello, in attached file different stress relief annealing temperature were introduced for different situation in austenitic stainless steel.
You can find theoretical temperatures for austenitic stainless steel annealing but the point shall be taken into consideration is the ability of heat treatment in decreasing the hardness and stress relief in austenite structure, because if you cannot control the process accurately there would be residual stress and sensitization which ends in SCC failure in corrosive media. So, it is not recommended to do annealing on Austenitic S.S. in the industry applications especially in corrosive media.
Maryam Soleimani
Dear Mrs. Soleimani,
Thank you very much for the information. I will check it out!
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