How does the die steel properties change after tempering?

The function changes of die steel after tempering vary with the type of steel selected, specifically including the following three points:

About the choice of cold die steel, mostly choose low temperature tempering, so its tempering before and after the functional difference is not big, plastic fundamental unchanged, strength slightly increased, hardness slightly decreased.

About the choice of hot die steel, mostly choose Chinese or high temperature tempering, so before and after tempering function changes significantly, strength and hardness will decrease, and plasticity and tolerance will increase significantly.

About the selection of special function of austenitic stainless steel or aging hardened steel, before and after tempering function changes significantly, hardness and strength will rise, plasticity and tolerance will decline.

If the steel is made of cold steel, the tempering difference is not big, the plasticity remains unchanged, the strength increases slightly and the hardness decreases slightly; if the steel is made of hot steel, the function changes obviously before and after tempering, the strength and hardness will decrease, while the plasticity and endurance will increase obviously.

Alloying elements also affect the tempered function of die steel

Silicon: dissolves carbide to increase its stability, prolongs the time of the first stage, and improves the temperature of the third stage.

Nickel, cobalt and aluminum: non-carbide constituent elements, which can delay the three stages of tempering. Aluminum obviously prevents the change of carbide.

Chromium: not only can constitute elements, but also can dissolve into cementite, three stages of postponing tempering, adding martensite tempering stability

Manganese: a large number of carburized body weight, reduce the change of carbide temperature, its effect and chromium, aluminum, silicon effect is opposite.

Molybdenum, tungsten, vanadium, titanium, niobium: strongly constitute carbide elements, do not dissolve into the cementite, more than 400 degree temperature to form a stable carbide, and cause secondary hardening.