Is it possible to repeat hardening?

[ludo123]

Hello, I would like to ask, is somebody can give an advise, I have a gear, with several teeth, which has passed through hardening process, but it is not done correctly. (Whole tooth is hardened end very brittle) Is it possible to undo hardening process and repeat it again? Heating it up to AC1 temperature? The material of the steel is f127. thanks.

 

[TVP]

I am not familiar with the steel designation f127, but it may be possible to re-harden the gear. What was the previous hardening process (induction, case carburizing, simple quench & temper)? If it was induction or Q&T, then yes, heating above Ac1 can be used to change the microstructure and enable a second hardening procedure. However, keep in mind that distortion and cracking will be possible with any reheating, so if the gear dimensions are already at the finished requirements then the gear may not remain dimensionally acceptable.

 

[stanweld]

You may not have to reaustenitize. Because the gear is too hard additional tempering may be required. You must also address the comments by TVP.

 

[ludo123]

thanks, I was talking with people from my university as well-dept of materials and they did tell me the same as you. Need to get over AC1-AC3, but of course in the case of finished piece it will bring problems with dimentions change and so on...