Martensite in solid solution/preciptation heat treatment

[Angus101]

Hello,

Probably a bit of a noob question here, hope you don't mind.

I'm reading somewhere that the first step in precipitation hardening is a solid solution quench process that leaves the alloy in a soft and ductile state.

Hold on, I thought quenching a solid solution in the a-phase produces martensite which is hard and brittle?

Or does this only apply for iron-carbon steels? Are high-alloy steels soft in a martensitic state?

Thanks for your time,

Angus101

 

[metengr]

Angus101;
There are no noob questions. The hardness of martensite is direct function of carbon content. Low carbon martensite can be very ductile, as quenched. The strengthening of the low carbon martensite is obtained from precipitation hardening.

 

[Angus101]

Hey thanks very much,

It's very confusing when textbooks make solid statements like that, they never explain the contradictions between something in one chapter and something else 10 pages previously.

 

[stanweld]

Angus101,
Not all alloy systems subject to precipitation hardening have a martensitic transformation from an FCC structure upon quenching.

 

[cloa]

In fact precipitate hardened isn't done from martensite forms as martensite is very hard and you want to form hard particles in a "soft" matrix and ageing from martensite reduces hardness somewhat with big toughness gain. Quenching may not be fast enough to generate a martensite but rather another supersaturated form of the alloy.

 

[metengr]

cloa;
Please review the facts below regarding low carbon martensitic stainless steel preciptation hardening alloys;

http://www.twi.co.uk/services/techn...102-precipitation-hardening-stainless-steels/