Heat treatment consists of several steps such as annealing, normalizing, quenching, tempering and tempering. Each step has a different temperature, time and cooling rate requirements to achieve different results. And NM500 steel plate heat treatment tempering (quenching + tempering) state.
a, tempering: steel factory by high temperature tempering heat treatment, this delivery state is called high temperature tempering state. High temperature tempering tempering temperature is high, is conducive to the complete elimination of internal stress, progress in plasticity and toughness, carbon structural, alloy steel, to ensure the hardenability of structural steel steel can be used high temperature tempering state delivery. Certain martensitic high-strength stainless steel, high-speed tool steel and high-strength alloy steel, due to high hardenability and the strengthening effect of alloying elements, often in the quenching (or tempering) after a high-temperature tempering, so that the carbides in the steel appropriate aggregation, to get the carbide particles coarser tempered Sohnite organization (similar to the spherical annealed organization), and therefore, this state of delivery of the steel has a very good cutting and machining performance
b, quenching: after heating to the phase change point temperature above, the process of sharp cooling. Improve the hardness of the material, but reduce the toughness
