Hot work die steel is an alloy tool steel suitable for manufacturing metal hot forming dies, such as hot stamping dies, hot extrusion dies, injection molds, hot upsetting dies, etc. As the press hot work dies work under high temperature and pressure for a long time, the die material must have high strength, hardness and thermal stability, especially high thermal strength, thermal fatigue, toughness and wear resistance.

Composition characteristics of hot forging die steel

1、Carbon content

Usually, this is the average carbon, the carbon mass fraction of 0.3% to 0.6%. Ensure that the material has high strength and hardness, high hardenability and good desirability and toughness.

2、Alloying elements

The added alloying elements include Cr, Mn, Si, Ni, W, Mo, V and other alloying elements. Among them, the role of Cr, Mn, Si and Ni alloying elements is to strengthen the ferrite and improve hardenability. W and Mo alloying elements are used to prevent tempering brittleness, and Cr, W, and Si alloying elements can increase the phase change temperature so that the shape does not undergo phase change during alternate heating and cooling, resulting in large volume changes, thus improving its durability thermal fatigue capability. In addition, tempering W, Mo, V, etc. in the form of carbide deposition, to obtain the secondary hardening, so that hot stamping die steel at higher temperatures can still maintain a high hardness, which is an important factor in the normal operation of hot forging steel. One of the conditions, Cr and Si can improve the oxidation resistance of steel.

Classification of steel for hot work tooling

There are many ways to classify hot work die steel, which can be classified by alloy content and performance after heat treatment, or by application, or by alloying elements.

(1)According to the use can be divided into hot stamping die steel, hot stamping die steel, injection mold steel and hot stamping die steel.

(2) According to heat resistance can be divided into low temperature resistant steel (350 ~ 370 ℃), medium heat resistant steel (550 ~ 600 ℃) and high temperature resistant steel.

(3)According to the unique performance is divided into high toughness hot work die steel, high heat resistance high strength stamping die steel, high wear resistance hot stamping die steel.

(4) According to the classification of alloying elements can be divided into low alloy hot forging steel (tungsten series, chromium series and molybdenum series), medium alloy hot forging steel and high alloy hot forging steel (tungsten, molybdenum series). series and chromium-molybdenum series); or divided into tungsten-based hot forging steel, chromium-based hot forging steel, chromium-tungsten-molybdenum-based hot forging steel. The high alloy die steel of chromium-tungsten series has less high temperature strength and heat resistance than tungsten-molybdenum series, and higher thermal fatigue strength and toughness than tungsten-molybdenum series.