corrosion test 3

[581127]

I plan to do some intergranular corrosion test for 316L stainless steel plate rewelded for 5 times in the same position. As we know, rewelding may cause carbide and sigma phase precipitating and resulting in corrosion resistance decrease. According to ASTM A262, method E may be used to access the sensitivity of intergranular corrosion due to carbide precipitation. What procedure can be adopted for the sensitivity of intergranular corrosion resulted from sigma phase(visible or unvisible) ? Who will please give me some advices for the test and tell me where I can find some research papers about the effect of rewelding on 316L or some relative information?
Thanks in advance

 

[TVP]

ASM HANDBOOK Volume 13 Corrosion has some good information on this subject. The section Evaluation of Intergranular Corrosion references a special tecnical publication from ASTM for intergranular corrosion of stainless steels:

Intergranular Corrosion of Stainless Alloys, STP 656, ASTM International, 1978.

You may obtain the ASM HANDBOOK from ASM International at

http://www.asminternational.org

and the ASTM STP from ASTM at

http://www.astm.org

.

 

[mcguire]

Are you sure your concerns are justified? Research has shown that it requires about 100 hours at the optimal precipitation temperature, 810C, to start to start to precipitate sigma or carbide in 316L.
The rule of thumb is that sigma can occur in austenitic alloys when
(%Cr-16%C)/%Ni > 1.7
which makes 316L a grade about which we don't worry about sigma (or sensitzation). Unless you have some very extreme situation like inches thick weldments, you're testing for a very improbable occurence.