17-7 PH Condition A - In-service Use
17-7 PH Condition A - In-service Use
(OP)
I have an application that is currently using 17-7PH material in condition A. Referring to the Mil-HDBK (MMPDS-01) it clearly states that this material should not be used in condition A. Does anyone on here know the reason that 17-7PH should not be used in condition A? I cannot find any specifc material that would help me on this matter.
Kind Regards
Rob
Kind Regards
Rob





RE: 17-7 PH Condition A - In-service Use
RE: 17-7 PH Condition A - In-service Use
The material is unstable and unpredictable.
You must use it in an aged condition.
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Plymouth Tube
RE: 17-7 PH Condition A - In-service Use
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Condition A is not untempered martensite, it is the lowest strength of the conditions - supersaturated austenite. Condition A has maximum ductility for forming and is supplied for welding and forming in this condition. The reason you don't use Condition A is that it can transform to martensite in service, which is want you do not want as above.
RE: 17-7 PH Condition A - In-service Use
I can echo the recommendation to not use it in condition A. Even if the high strength is not needed, corrosion resistance as well as fatigue properties are better in the aged conditions.
rp
RE: 17-7 PH Condition A - In-service Use
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Plymouth Tube
RE: 17-7 PH Condition A - In-service Use
RE: 17-7 PH Condition A - In-service Use
Condition A and solution annealed condition are the same for 17-4PH sst. In condition a the tensile strength is close to 150 ksi, very strong, but elongation is less than 10% See the following website: h
It also has the warning on martensite and use in the A condition.
RE: 17-7 PH Condition A - In-service Use
Do not use the rod in Condition A, to unpredictable with regard to properties. Do an aging treatment to be sure.
RE: 17-7 PH Condition A - In-service Use
I am not going to nit pick with you regarding the UTS, YS properties but a published value of 10% elongation is not correct for Condition A. Think about this for a minute – why would such an alloy after a conditioning treatment with no precipitates from aging have such poor elongation and is provided in this condition for forming and welding? This makes no sense.
The PH hardening stainless steels are very formable in Condition A they work harden and can transform to untempered martensite from cold working, that is how they are sold. Condition A affords welding and forming (cold working) operations before aging or reheat treatment. Condition A is not a condition that is used because it is an intermediate step in the final heat treatment for these alloys.
RE: 17-7 PH Condition A - In-service Use
17-7 PH (UNS S17700) is normally supplied in the solution-annealed condition (condition A), in which it is soft and formable. Heat treatment is accomplished through the use of the transformation-hardened (TH) or refrigeration-hardened (RH) procedures indicated in Table 15. The choice of method of heat treatment is usually dictated by the ease with which the particular sequence fits into the production techniques of the user. Parts that receive significant deformation should be heat treated to RH 950, or soft spots may result.
This alloy is also supplied in the cold-rolled condition (condition C). Here, transformation has been achieved by cold rolling, and heat treatment is reduced to a single step: 480 °C (900 °F) for 1 h. Although strength and stress-corrosion resistance are greatly increased by this treatment, ductility is reduced and formability is limited.
RE: 17-7 PH Condition A - In-service Use
When you age these alloys you are altering the microstructure. A lower strength condition does not infer better ductility.
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Plymouth Tube
RE: 17-7 PH Condition A - In-service Use
RE: 17-7 PH Condition A - In-service Use
With 17-7 you do get the lowest strength in the "A" condition, but the results can be highly variable and not suitable for any service.
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Plymouth Tube
RE: 17-7 PH Condition A - In-service Use
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It is readily available in the aged condition from distributors such as www.specialtysteelsupply.com
RE: 17-7 PH Condition A - In-service Use
RE: 17-7 PH Condition A - In-service Use
RE: 17-7 PH Condition A - In-service Use
I am not trying to be funny or sarcastic here but, we are not dealing with 17-4 PH, we are dealing with 17-7PH. You keep referring to 17-4PH. The 17-4 PH is truly a martensitic microstructure from the get go and ages with precipitation. 17-7 PH is not the same as 17-4 PH. IN this case, 17-7PH is a semi-austenitic precipitation hardening stainless steel.