What are the porposes of quenching and tempering of SMLS steel tube

Quenching of SMLS steel tube:
Operation method: heat the SMLS steel tube to the phase change temperature AC3 or AC1 above, keep it for a period of time, and then quickly cool it in water, nitrate, oil or air.

Purpose: the purpose of quenching is to obtain high hardness martensite structure. Sometimes, when quenching some high alloy steels (such as stainless steel and wear-resistant steel), it is to obtain uniform austenite structure to improve wear resistance and corrosion resistance.

Application points: 1. Generally used for carbon steel and alloy steel with carbon content more than 0.3%; 2. Quenching can give full play to the strength and wear resistance potential of steel, but at the same time it will cause great internal stress and reduce the plasticity and impact toughness of steel, so tempering is necessary to obtain better comprehensive mechanical properties.

Tempering of SMLS steel tube:
Operation method: reheat the quenched SMLS steel tube to a temperature below AC1, cool it in air, oil, hot water and water after heat preservation.

Purpose: 1. Reduce or eliminate the internal stress after quenching, reduce the deformation and cracking of the workpiece; 2. Adjust the hardness, improve the plasticity and toughness, and obtain the required mechanical properties; 3. Stabilize the size of the workpiece.

Application points: 1. Low temperature tempering is used to keep the high hardness and wear resistance of steel after quenching; medium temperature tempering is used to improve the elasticity and yield strength of steel under the condition of maintaining certain toughness; high temperature tempering is used when maintaining high impact toughness and plasticity and sufficient strength; 2. Tempering between 230 ~ 280 ℃ for general steel and 400 ~ 450 ℃ for stainless steel should be avoided as far as possible, as it will generate temper brittleness.