Egyptian armor plate tank weld cracking

US Army Abrams tanks built in Lima, Ohio for sale to Egypt. Manufacturer used austenitic stainless steel filler metal to avoid hydrogen cracking in armor steel, but failed to control dilution; ended up with martensite streaming in the weld and shipped cracked tanks. State Department embarrassment. Tom's student at Army Research Labs (Watertown) was working on the problem.

My example of that: thirty years ago I had a student working at Army Research Labs over here in Watertown, working on hydrogen cracking of armor steels for the Army. He called me up. The State Department was all over the US Army because they'd agreed to sell the Egyptians these tanks. They were being built in Lima, Ohio. Anybody from Ohio? This is why I like Lima beans. Lima, Ohio is where the US Army's tank plants were — building Abrams for the Egyptian army. They were building some older model, but they were having a problem. As I told you, when the Navy started welding HY-80, this was one of the first cases too. They basically couldn't solve a hydrogen cracking problem, so they used austenitic stainless steel filler metal. The austenitic stainless steel will dissolve ten times the hydrogen, and it's ten times more resistant than a carbon ferritic steel weld. So they decided to weld the Egyptian tanks with austenitic stainless steel — only they didn't worry about how much dilution. Depending on the weld metal they were using, they were getting cracking.

Brief reference. Austenitic filler metal welded to armor steel produced a martensite-austenite mixture in the diluted zone, which cracked. Used to illustrate the Fe-Cr-Ni phase diagram regions to avoid.

Anyway, you can get austenite-martensite — this is what happened with the Egyptian tanks. They used an austenitic filler metal with the armor steel, and they ended up in this region and they got cracking because of the martensite. Some of these surgical stainlesses are over here. You can get in these regions, you can get the duplex stainless steels, but you have to be careful about your welding procedure.