Basic properties of hot work die steel

Hot work die steel subjected to a great impact force during production.  The die cavity and high temperature metal touch, repeatedly heating and cooling, its operating conditions are very harsh. In order to satisfy the operation requirements of hot die, hot work die steel shall have the following base characteristics:

(1) High temperature strength and excellent toughness. A hot die, especially a hot forging die, will simply crack if it does not have high strength and excellent toughness due to its high impact force and high impact frequency.

(2) Excellent wear resistance, due to the hot die in addition to being deformed by the blank conflict wear, but also by high temperature oxidation corrosion and iron oxide chip grinding, so the demand for hot die steel has a higher hardness and adhesion.

(3) High thermal stability. Thermal stability refers to the ability of steel to maintain its mechanical properties at room temperature for a long time at high temperature. When die/mould is heat with frequent contact of hot metal (solid or molten state), so the die/mould surface temperature is very high, usually around 400 ~ 700℃. This requires hot work tool steel at high temperature does not occur thermalization, with high thermal stability, or the mold will occur plastic deformation, heap collapse and failure.

(4) Very good heat resistance fatigue, the working characteristics of the hot mold is repeated heat and cold, constitute a large cyclic thermal stress,. Under the effect of repeated thermal stress, mould surface will form a network cracks, this phenomenon is called thermal fatigue, die due to thermal fatigue and premature fracture, is one of the primary causes of failure of hot die. So hot work die steel needs to have outstanding thermal fatigue resistance.

(5) High hardenability. The ordinary size of hot work die is relatively large, hot forging die in particular, in order to make the mechanical properties of the entire die section uniform, this requires hot die steel has good hardenability.

(6) Excellent thermal conductivity.  High induced heat energy caused mechanical properties to decline.   It would be ideal if we could improve tool steel conductivity so as to alleviate the damage.

(7) Excellent forming process performance to meet the requirements of forming.