17-4 H1150 and H1075 3

[Flesh]

I have specified round pins be made of 17-4 H1150 double-aged. I want to freeze these pins prior to insertion into bores. My first question, any metallurgical change that can occur during freezing step that should cause me concern?

Second question. My supplier, in their infinite wisdom, supplied me condition H1075 because it's "equal or better in strength and therefore meets my requirements". While I work with my purchasing team to unravel this debacle, same metallurgical question as above but for condition H1075.

Thank you for your time.

 

[EdStainless]

If the HT was done correctly then freezing them will have no effect on them.
You are talking about double H1150 and not overaged to H1150M, right?
As long as they are making the higher elongation and impact toughness then they should work, but....
If this was mine I would demand to have the parts reaged at the correct tmep.

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P.E. Metallurgy, Plymouth Tube

 

[BiPolarMoment]

Who on earth would supply a clearly out of spec part (and put it in writing?). Not that I don't have a couple examples of stupidity.

Sounds like you need a new supplier .

 

[monkeydog]

You could pay your supplier with BitCoins as they are as good or better than the currency you were going to pay them with.

 

[MagBen]

1 Bitcoin > 1,000 USD. I would be happy if paid with BTC . For me, as long as the elongation or impact is not a concern, I do not care if it is H1075 or H1150. However, I guess the double-aged H1150 is actually H1150M (1400F+1150F, strictly speaking 1400F is a solution, 1150F is an overage), if this is the case, H1150M has a big difference from H1075, and toughness is probably important for your applciations.
I do not foresee any undesirable metallurgical consequences after freezing, although the impact strength will decrease while tensile increases in both conditions.

 

[Flesh]

Thank you everyone for your replies. You have confirmed my findings (or lack thereof) regarding change in properties after freezing. I specify H1150 double-aged as: 1150 4hrs, air cool, plus 1150 4hrs, air cool (ref. ASTM A564-02a). As most of you have implied, a proper engineering review of the lowered toughness and ductility in H1075 would be prudent on my part.

 

[EdStainless]

Since you are going to a higher aging temp you do not need to re-anneal, you can just re-age at the higher temp.
Make sure that he understands that he will be doing this no charge, and that you want the furnace charts.
I have asked guys to send me a photo of them holding the part before the second age cycle, then you know that they actually cooled it.


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P.E. Metallurgy, Plymouth Tube