UNS S17400 ASTM A564

[jimsan]

A customer has his own specification of the above material which shows mechanical properties above H1150M and below H1150D condition.
In the past the heat treatment for H1150M condition has always been :-
Soln Treat @ 1040C Water Quench followed by 760C held for 2 hrs air cool followed by 620 C for 4 hrs air cool.

H1150D condition is:-
Soln Treat @ 1040C Water Quench followed by 620C held for 4 hrs air cool followed by 620 C for 4 hrs air cool.

Can these temperatures/times be varied in some way to give properties between 1150M & 1150D?

 

[EdStainless]

Why?
does the H2250 have enough elongation? if so then stick with it.
If the spec has min/max properties then ask for the heat treatment.
Longer aging at 1150F will reduce strength, but I don't know how much.

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[metengr]

Can these temperatures/times be varied in some way to give properties between 1150M & 1150D?

If this material is being supplied to this ASTM specification, the answer is NO for Type 630 (UNS S17400).

 

[MikeMet]

The critical temperature in the heat treatments you show is the intermediate sub-critical anneal. For H1150M that is the 760C for 2 hrs. A change in that temperature will give different properties when followed by the 620C hardening heat treatment. The lower the temperature of the sub-critical anneal, the closer the properties will be to those of H1150 after aging. I don't know what the lower temperature limit is for this sub-critical anneal where it will not affect the response to the H1150 treatment. I would expect if you did a sub-critical anneal at 620C, like is H1150D above, followed by an aging treatment at 620C, you will get properties that will meet the requirements for H1150 in ASTM A705 or other ASTM Standards for 17-4PH sst. You can hold 17-4PH sst at the 620C temperature for a long time, over 10 hrs before you begin to see significant changes in the properties.

 

[EdStainless]

The problem with these modified heat treatments in that most people only check hardness and tensile properties.
You really have no clue what the toughness, fatigue, stress rupture and so on actually are. In some of these alloys you can drive down the toughness without changing the tensile.
You might see this in tensile elongation, but you might not.

I would not try to make up a new heat treatment. I would select a standard one that will result in properties that meet my requirement. If there isn't one then look into using another alloy.

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