Quenching and Tempering Treatment of 45Cr Steel

Cr can increase the hardenability of steel, improve the strength and tempering stability of steel, and has excellent mechanical properties. Cr steel should be used for large or important quenched and tempered workpieces. But Cr steel has the second type of temper brittleness .

For the quenching and tempering of 45Cr steel, various parameters and process cards have regulations. Our experience in actual operation is:

(1) 45Cr steel should be oil-cooled after quenching. The hardenability of 45Cr steel is better, it can be hardened when cooled in oil, and the deformation and cracking tendency of 45Cr steel are small. However, in the case of tight oil supply, small enterprises Workpieces with uncomplicated shapes can be quenched in water without cracking, but the operator must strictly control the temperature of entering and exiting water based on experience.

(2) The hardness of 45Cr steel is still high after quenching and tempering, and the second tempering temperature must be increased by 20~50°C, otherwise, it is difficult to reduce the hardness.

(3) After 45Cr steel is tempered at high temperature, the complicated shape is cooled in oil, and the simple one is cooled in water. The purpose is to avoid the influence of the second type of temper brittleness. 45Cr steel after tempering and rapid cooling should be treated with stress relief if necessary.