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Why do I need hardened HSS tools?
HSS is a high alloyed tool steel that contains a variety of alloying elements. Poor heat transfer and poor plasticity therefore, steel must be quenched at high speed for four main benefits.
Preheat in an air furnace first, then in a salt bath furnace to avoid the risk of explosion and facilitate safe production.
Shorten the high temperature heating time, reduce the tendency of high temperature oxidation decarburization. Reduce the possibility of stress and deformation cracks from cr8 mold steel processing.
Medium-temperature preheating is generally around 850 ℃, pearlite transformation into austenite at a lower temperature, processing is conducive to reducing the transformation stress.
What is the effect of carbon on HSS? Carbon is the main component of high speed steel. The mechanism of work tool steel is the generation and transformation of carbide, i.e. dissolution, precipitation and aggregation. The content should be appropriate, not too much and not too little. When the content is low, it cannot form sufficient amount of complex carbide, so that the carbide dissolved in the solid solution during quenching is reduced, thus reducing the hardness, red-hardness and wear resistance of the steel. At high carbon content, the concentration of carbon and alloying elements increases during heating and quenching, which increases the hardness and red-hardness of the steel, but also has some adverse effects, such as increasing carbide inhomogeneity, increasing plasticity, decreasing brittleness, and decreasing processability (forging, rolling, etc.). Cracking will lower the melting point of the steel, so hot work die steel is prone to overheating and overheating. Increasing the carbon content will increase the residual austenite (rR) after quenching and make tempering more difficult. The original M35 steel carbon content is low (0.80%-0.90%), by tempering can not reach 67HRC high hardness. 501 steel (M2A1) carbon content is high, there are many problems. The carbon content of these two steels has now returned to normal. The new version of GB/T9943 standard has a large change in carbon content compared with the original standard.
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