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Die steel--machine knife (a)
- Jul 09, 2018 -

Molds can be divided into cold moulds, hot moulds and plastic molds, which are used for forging, stamping, cutting and die casting. Because of all sorts of mould USES different, complex working conditions, so the mold steel, according to the working conditions of mold manufacturing, should have high hardness, strength, wear resistance, enough toughness, and high hardenability, hardenability and other process performance. Because this kind of use is different, the working condition is complex, so the performance requirement of die steel is different.


Cold working die includes cold punching die, drawing die, drawing die, stamping die, rubbing die, rolling die, cold upsetting die and cold extrusion die. The cold mold has steel, according to the working conditions of the tool, it should have high hardness, strength, abrasion resistance, enough toughness, as well as high hardenability, hardenability and other technical properties. The alloy tool steel used for such purposes generally belongs to high carbon alloy steel, with a carbon quality score of more than 0.80%. But for some high requirement of abrasion resistance, small deformation of mould steel after quenching, high chromium mass fraction is 13%, and in order to form a large number of carbide, carbon in steel quality score is high, up to 2.0% ~ 2.3%. The carbon content of cold die steel is high, and its structure is mostly pereutectic steel or lepidoid steel. The steel commonly used are high carbon low alloy steel, high carbon high chromium steel, chromium molybdenum steel, medium carbon chromium tungsten alloy steel and so on.


[applications] : cold work mould used for cold (working temperature below 200 ~ 200 ℃) under the metal forming, such as cold punching die, cold extrusion molding, shear modulus, etc. This kind of mould is subjected to great pressure, strong friction and certain impact, therefore, high hardness, wear resistance and enough toughness are required. In addition, the complex shape, precision, large mold also requires high hardenability and small heat treatment deformation.


[chemical composition]: cold mold steel generally has high carbon content, wC=1.0%~2.0%, to obtain high hardness and wear resistance. Cr, Mo, W, V and other alloy elements were added to improve wear resistance, hardenability and temperature-resistance.


[commonly used cold die steel]:Crl2 section steel includes Cr12, Cr12MoV, etc. This kind of steel has good hardenability and abrasion resistance, small heat treatment deformation, and is often used for large cold die. Among them, Crl2MoV steel has better strength and toughness, with the most extensive application, except that its wear resistance is not as good as Cr12 steel. Cr12MoV is widely used for circular knife, metal shear blade, shredder knife. The cold-making mould with small size can be made of low-alloy cold-making die steel CrWMn, etc., or steel 9SiCr for circular knife or bearing steel GCr15 for ice resurfacing blade.


[heat treatment]:Crl2 section steel belongs to leibsen steel, which should be repeatedly forged and annealed before processing. The final heat treatment of Cr12 section steel is usually quenching and tempering, and the tempered martensite, carbide and residual austenite microstructure are obtained, with a hardness of 60~64HRC.