17-4 PH H1100 Impact Strength vs. Temperature 3

[Velocityraptor]

Hello,

I am have a customer asking me to make some parts per the following material requirement:

ASME SA-564 17-4PH (TYPE 630) H1100 OR ASTM A564 17-4 PH H1100

REQUIREMENTS TESTED PER ASTM A370:
ULTIMATE TENSILE STRENGTH (20 DEG C): 140 KSI MIN
0.2% PROOF STRENGTH (20 DEG C): 115 KSI MIN
ELONGATION 14% MIN

A TEST SPECIMEN MADE FROM EACH NEW HEAT BATCH WIL LBE TESTED AT 300 DEF F FOR THE FOLLOWING PER ASTM E21:
ULTIMATE TENSILE STRENGTH (149 DEG C): 140 KSI MIN
0.2% PROOF STRENGTH (149 DEG C): 101.8 KSI MIN

IMPACT TEST REQUIREMENTS: TEST IN ACCORDANCE WITH THE SPECIFICATION. REQUIREMENT >27J AT TEMPERATURE OF -40 DEG F

The strength requirements are straight out of the ASME spec and we have not had a problem meeting these requirements, however the sub-zero impact test is giving us issues.
Now, according to the ASME SA-564 the post-heat treat impact strength (Charpy-V) of the material should be 34 Joules minimum tested at room temperature. We have tried multiple material suppliers and none of them will guarantee the impact strength of the material at the -40 deg F test condition. We even tried to buy some material and perform the test on it, the impact strength was an average of 8 Joules, significantly below the requirement. I have tried to find some reliable data on this, however I could not find much, only this:

http://www.interlloy.com.au/our-pro...precipitation-hardening-stainless-steel-bar/.

According to the interalloy data sheet, the impact strength at -40 deg F for H1100 should be between 103 and 54 Joules. Does this mean that we got a bad heat treat? Is there any other data available on this subject? Is the customer's requirement unrealistic? I looked through MMPDS and there was no data on impact strength for 17-4 PH. Any help would be greatly appreciated!

Thanks!

 

[jwhit]

It has been a number of years since I did anything with 17-4PH with impact requirements, but I seem to recall that a proper solution treatment was critical as was a long enough hold time during the aging cycle. As I recall a 4hr minimum age is needed, longer if heavy sections. Hopefully, others on here can add to this and/or correct anything I have misstated.

 

[EdStainless]

Well, it should make it, but this is a difficult requirement.
The old data that I have shows RT Chapry as 25lb-ft min, with 45 typical.
The curves and tables from the Armco book show that it should make it.

First, reheat treat a piece. Every time that you re-anneal and age this alloy you get grain refinement.
Second, make sure that they are in the longitudinal direction.
Third, after aging if your strength is above min by a large margin i would re-age for another 2 hours and see if it comes down, if not I would bump the aging temp up 25F and give it 2 hr more. My gut feel is that you will need to be under 155ksi UTS in order to have enough toughness.

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