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  1. #1
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    Default Are 4140 HT and 4140 HTSR the same thing?

    OK guys, I know this may sound like a stupid question to some, but I have asked this question to two different metal suppliers and can't get a straight answer. I don't do a lot of prehard parts. Some, but not much. I am trying to pick up a new customer and instead of the usual 4140 PH or HT on the print, all of his prints say 4140 HTSR. Is this a different condition than HT, or is 4140 "heat treated" normally stress relieved too, but they just don't say that, or what? Thanks in advance, and everyone have a happy turkey day.

  2. #2
    RJT
    RJT is offline Stainless
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    I was ordering some steel and asked my supplier and he said if the bar is hot rolled, and heat treated in process, it is considered stress free. If the bar is heat treated after rolling as a secondary operation, it then goes through a stress relieveing cycle. In either case PHT 4140 should be free of stress. Now, this is a salesman that gave me that informtion, but it sounds logical. Rolled hot, it's already stress free. Cold finished would need stress relieving and I don't know if it's always supplied stress relieved. I think you need to check with your supplier to ensure it. I don't think it's a stupid question at all, in fact a pretty intelegent one.

  3. #3
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    I guess my problem then is, if my suppliers don't know what they are getting, then how am I supposed to know what I am getting? I need to do some more homework on this and find out for sure though.

  4. #4
    RJT
    RJT is offline Stainless
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    Your supplier should definately know. Mine knew what he was suppling to me, but didn't know if it was an absolute throughout the industry standard.

  5. #5
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    I just found this old thread in the General forum. It seems to indicate that HT, HTSR, and PH are all the same thing.

    4140 HT same as 4140 pre hard ?

  6. #6
    HuFlungDung is offline Diamond
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    Quote Originally Posted by RJT View Post
    I was ordering some steel and asked my supplier and he said if the bar is hot rolled, and heat treated in process, it is considered stress free. If the bar is heat treated after rolling as a secondary operation, it then goes through a stress relieveing cycle. In either case PHT 4140 should be free of stress. Now, this is a salesman that gave me that informtion, but it sounds logical. Rolled hot, it's already stress free. Cold finished would need stress relieving and I don't know if it's always supplied stress relieved. I think you need to check with your supplier to ensure it. I don't think it's a stupid question at all, in fact a pretty intelegent one.
    Heat treated 4140 is oil quenched, so it definitely gets cold somewhere in there. It would most likely be Rc45 to Rc50 if simply heat treated. The stress relief is, to my way of understanding it, way overdrawing the temper of the hardened (quenched) bar, and the hardness is much reduced from maximum so as to reduce the quench stress. I've had the odd piece with a radial crack from the center outwards. My thoughts: it cracked on quenching.

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