3 KINDS TOOL STEEL
Die steel can be roughly divided into cold work tool (die) steel, hot work tool (die) steel and plastic mould (die) steel, which are used for forging, stamping, cutting and die casting. Due to the different uses and complex working conditions of various dies, the die/tool steel should have high hardness, strength, wear resistance, sufficient toughness, high hardenability, hardenability and other technological properties according to the working conditions of the die. Due to different uses and complex working conditions, the performance requirements of die steel are also different.
1.1 Cold working tool (die) steel includes cold stamping die, drawing die, drawing die, embossing die, rolling die, rolling plate, cold heading die and cold extrusion die. According to the working conditions of the tools, the cold working dies should have high hardness, strength, wear resistance, enough toughness, high hardenability, hardenability and other technological properties. The alloy tool steel used for this kind of purpose generally belongs to high carbon alloy steel, and the carbon content is more than 0.80%. Chromium is an important alloy element of this kind of steel, and its mass fraction is usually not more than 5%. However, for some die steels with high wear resistance and small deformation after quenching, the highest chromium content can reach 13%, and in order to form a large number of carbides, the carbon content in the steel is also very high, up to 2.0% ~ 2.3%. The carbon content of cold working die steel is high, and most of its microstructure belongs to hypereutectoid steel or ledeburite steel. The commonly used steels are high carbon low alloy steel, high carbon high chromium steel, chromium molybdenum steel, medium carbon chromium tungsten plutonium steel, etc.
1.2 Hot work tool (die) steel is divided into hammer forging, die forging, extrusion and die casting, including hot forging die, press forging die, stamping die, hot extrusion die and metal die casting die. In addition to the huge mechanical stress, the hot deformation die has to bear repeated heating and cooling, which causes great thermal stress. In addition to high hardness, strength, red hardness, wear resistance and toughness, hot work die steel should also have good high temperature strength, thermal fatigue stability, thermal conductivity and corrosion resistance. In addition, high hardenability is required to ensure consistent mechanical properties of the whole section. For die casting die steel, the surface layer should not produce cracks after repeated heating and cooling, as well as withstand the impact and erosion of liquid metal flow. This kind of steel generally belongs to medium carbon alloy steel, with carbon content of 0.30% ~ 0.60%, which belongs to hypoeutectoid steel. Some steels become eutectoid or hypereutectoid steel due to adding more alloy elements (such as tungsten, molybdenum, vanadium, etc.). The commonly used steels are chromium manganese steel, chromium nickel steel, chromium tungsten steel, etc.
1.3 Plastic molud steel includes thermoplastic mold and thermosetting plastic mold. The steel for plastic mould is required to have certain strength, hardness, wear resistance, thermal stability and corrosion resistance. In addition, good processability is also required, such as smaller heat treatment, better processability, corrosion resistance, good grinding and polishing performance, good repair welding performance, high roughness, good thermal conductivity and stable size and shape under working conditions. In general, hot work die steel can be used for injection molding or extrusion molding, and cold work die steel can be used for thermoset forming and high wear resistance and high strength die.
The steel grades of tool steel
2.1 Cold work tool steel
High carbon low alloy cold working die steel
9SiCr, 9CrWMn, CrWMn, Cr2, 9Cr2Mo
Wear resistant cold working die steel
Cr4W2MoV, Cr5Mo1V, Cr6WV, Cr12, Cr12MoV, Cr12W
Impact resistant cold working die steel
4CrW2Si, 5CrW2Si, 6CrW2Si
Carbon tool steel for cold working die
T7, T8, T9, T10, T11, T12
High speed steel for cold working die
W18Cr4V
Non magnetic die steel
2.2 Hot work tool steel
Low heat resistance hot working die steel
5CrMnMo,5CrNiMo
Medium heat resistant hot working die steel
8Cr3
Hot working die steel with high heat resistance
3Cr2W8V
2.3 Plastic mould steel
Carbon plastic die steel
SM45,SM50,SM55
Pre hardening plastic die steel
3Cr2Mo,40Cr,42CrMo、
Carburized plastic die steel
20Cr,12CrNi3A
Age hardening plastic die steel
Corrosion resistant plastic die steel
2Cr13, 4Cr13, 9Cr18, 9Cr18Mo, cr14mo4v, 1Cr17Ni2 in the steel plate (plate), there are many materials are included in the die steel series: 45 (45), P20, S45C, S50C and so on.
