Adding micro-alloy elements Ti, Nb, and V in a CA6NM martensitic stainless steel tube is usually expected to form a nitrogen compound with C and N.
Si is a strong ferrite stabilizing element in martensitic stainless steel. Si in CA6NM stainless steel can suppress temper embrittlement and the decomposition of retained austenite during tempering.
First of all, as a deoxidizer, we often add Al in CA6NM stainless steel. At the same time, Al is also a ferrite forming element. As a result, its promoting effect on ferrite formation is about 2.5~3 times of that of Cr.
Mn in CA6NM expands the austenite phase zone in the phase diagram. In steel, the stability of Mn to austenite is only below Ni, which can greatly improve the hardenability of steel.
Cu in CA6NM has a weaker effect on the formation of austenite. A small amount of Cu addition can not optimize the martensitic microstructure of martensite.
Mo – the addition of alloying element Mo in CA6NM martensitic stainless steel is beneficial to the strength. And also to toughness and corrosion resistance. Mo is a ferrite forming element. It can reduce the Ms temperature.
Ni – the alloying element has no strengthening effect on the matrix of stainless steel CA6NM. According to the known Cr will promote the formation of ferrite.
Cr – one of the major alloying elements in martensitic stainless steel CA6NM. Cr in CA6NM plays a decisive role in corrosion resistance.
CA6NM ASTM A743 is a kind of low carbon martensitic stainless steel. It has good mechanical properties, CA6NM equivalent grades are as following
Since martensite will be produced after air cooling, CA6NM is not suitable for cutting, so it must be softened by heat treatment before machining. CA6NM heat treatment can be divided into high-temperature tempering and complete annealing