Heat treating a part for a second time
Heat treating a part for a second time
(OP)
I have a 4140 plate 1"x6"x13" that is 40 RC. I would like to use the plate for a different application that requires a hardness of 52-55 RC.
Following the heat treat (to 52-55 RC), I will Blanchard grind the part to 3/4" thick.
Do I need to anneal the part before prior to the 52-55 RC heat treat. If I do not anneal the part, do I significantly increase the risk of cracking (or excess warping)?
Thanks
Following the heat treat (to 52-55 RC), I will Blanchard grind the part to 3/4" thick.
Do I need to anneal the part before prior to the 52-55 RC heat treat. If I do not anneal the part, do I significantly increase the risk of cracking (or excess warping)?
Thanks





RE: Heat treating a part for a second time
However, one question that I have is your hardness range - are you attempting to thru harden this plate at 52-55 HRC? If so, 4140 will not work for your desired plate thickness.
RE: Heat treating a part for a second time
RE: Heat treating a part for a second time
RE: Heat treating a part for a second time
RE: Heat treating a part for a second time
We had a gear ring (int. teeth) about 9" OD, 7.5 in ID, and 1.5 in thick. The blank hardness 32 HRC. Final thru hardnes -48-52 HRC. This gear cracked at a few locations.
SO we decided to go in for nitriding and it worked.
Another important thing to remember is the warpage it creates when a 13" length plate is Heat treated 13".
To avoid these problems it is best to nitride. But again do you need this hardness only for wear resistance or the load? If it is load that is driving this H/T then it is best to anneal it prior to hardening. Then grind it to proper size.
RE: Heat treating a part for a second time
Interested to know the reasoning for anneal prior to hardening.