2017年3月7日星期二

Heat treatment of quenching, tempering

Here we heat the # steel
The steel will be heated to a certain temperature, in the insulation for some time, and then in water, salt water or by the medium of rapid cooling, this heat treatment process called quenching.
The effect of quenching: strengthening steel, which is one of the most common heat treatment process. We can also through the tempering process, change the internal structure of steel, so that the workpiece to obtain different mechanical properties to meet the different working conditions, better play the potential of material properties.
E.g:
 quenching steel + low temperature tempering can improve the hardness and wear resistance.
 quenching steel + medium temperature (high temperature) tempering, you can get a good overall performance, you can ensure adequate toughness under the premise of improving the strength of steel.
Common quenching method:
 single liquid quenching: the advantages of simple and easy way to achieve mechanization, the shortcomings of the work piece easy to crack. So it is only suitable for simple carbon steel and alloy steel parts.
 two-liquid quenching: mainly used in the water must be quenched steel, such as the larger size of the high-carbon steel parts and some alloy steel parts.
 grading quenching: due to the slow cooling of the classification quenching, it is only applicable to the smaller size of carbon steel and alloy parts.
 isothermal quenching: isothermal quenching parts of the internal stress and deformation of small, suitable for small precision parts quenching, such as precision gears.
Tempering is to heat the work piece after quenching to a certain temperature, heat a certain time, in a certain way to cool a heat treatment process. Tempering is followed by quenching, and is usually the last process of heat treatment.
In accordance with the performance requirements after tempering,  
3.
Low temperature tempering. Used for cutting tools, measuring tools, molds, etc., to eliminate the steel due to quenching and internal stress generated, and to maintain the quenching of high strength and wear resistance.
Medium temperature . Generally used for all kinds of springs, molds and impact tools, so that the steel to obtain a higher elasticity, a certain degree of toughness and hardness.
High temperature . Mainly used for high strength, high toughness of the important structural parts, such as the spindle, crankshaft, cam, gear and connecting rod, so that the steel to get better overall performance.

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