What are the effects of quenching martensitic stainless steel?

For martensitic chromium-nickel stainless steel, most applications require a quenching and tempering heat treatment process. In this process, different alloying elements and their addition amounts will have different effects on the hardenability of the material.

When quenching martensitic stainless steel, it is quenched from a temperature of 925-1075°C. Because the phase transformation speed of the structure is low, complete hardening can be achieved regardless of oil cooling or air cooling. Also in the necessary tempering process, a wide range of different mechanical properties can be obtained due to different tempering conditions.

In martensitic chromium stainless steel, because the addition of chromium can enhance the hardenability of iron-carbon alloys, the application range of quenched martensitic stainless steel is still relatively wide. The main function of chromium is to reduce the critical cooling rate of quenching and significantly enhance the hardenability of martensitic stainless steel. Judging from the C curve, because the addition of chromium slows down the austenite transformation speed, the C curve shifts significantly to the right.

In martensitic chromium-nickel stainless steel, the addition of the alloying element nickel can enhance the hardenability and hardenability of martensitic stainless steel. Stainless steel with a chromium content close to 20% has no quenching ability if nickel is not added. Adding 2%-4% nickel can restore the quenching ability. However, the nickel content cannot be too high, otherwise too high nickel content will not only expand the r-phase zone, but also reduce the Ms temperature, which will cause the steel to become a single-phase austenite structure and lose its quenching ability. Choosing the appropriate nickel content can enhance the tempering stability of martensitic stainless steel and reduce the degree of temper softening.

In addition, adding molybdenum element to martensitic chromium-nickel stainless steel can also increase the tempering stability of martensitic stainless steel.

Although ferritic stainless steel does not form an austenite structure at high temperatures, it cannot be hardened through the quenching process, but low chromium stainless steel will undergo partial martensitic transformation.

Austenitic stainless steel belongs to the iron-chromium-nickel series and iron-chromium-manganese series stainless steel and has an austenitic structure. Therefore, it will show high strength and excellent elongation performance in a wide range from low temperature to high temperature. The non-magnetic full austenite structure can be obtained by performing a rapid solution treatment starting from 1000°C or above, so as to obtain excellent corrosion resistance and maximized elongation performance.