Low-temperature treatment method for improving 42CrMo hardened and tempered steel performances

Abstract

The invention discloses a low-temperature treatment method for improving 42CrMo hardened and tempered steel performances. The method includes the steps: (1) placing 42CrMo hardened and tempered steelworkpieces with indoor temperature into a temperature-controllable low-temperature cooling device, and reserving gaps among the workpieces; (2) pre-cooling 42CrMo hardened and tempered steel workpieces in the temperature-controllable low-temperature cooling device by the aid of cooling media at the temperature of 40 DEG C below zero, and keeping the temperature for 30 minutes; (3) cooling the pre-cooled workpieces in the temperature-controllable low-temperature cooling device by the aid of the same cooling media to reach the temperature ranging from 100 DEG C below zero to 150 DEG C below zero, and keeping the temperature; (4) closing a refrigeration system of the temperature-controllable low-temperature cooling device after the workpieces are kept at the low temperature, enabling the temperature of the workpieces to naturally rise, and taking out the workpieces when the workpieces reach the temperature of 50 DEG C below zero or more; (5) placing the taken out workpieces treated at lowtemperature into the air, enabling the temperature of the workpieces to naturally rise to reach the indoor temperature to prepare 42CrMo hardened and tempered steel. The method is simple and convenient to operate and low in cost, energy conservation and emission reduction can be achieved, and the service life of the 42CrMo hardened and tempered steel is effectively prolonged.

Description

technical field [0001] The invention belongs to the technical field of heat treatment, in particular to a low-temperature treatment method for improving the properties of 42CrMo quenched and tempered steel. Background technique [0002] The article "Development of Domestic 42CrMo Quenched and Tempered Steel Crankshaft" in the 2007 No. 6 issue of "Auto Engine" magazine introduced a method to improve the performance of 42CrMo quenched and tempered steel by changing the quenching and tempering temperature of the quenching and tempering process. The method is First fix the quenching temperature and then gradually increase the tempering temperature to obtain 42CrMo quenched and tempered steel with better comprehensive mechanical properties. The disadvantage is that only the quenching and tempering temperature is changed on the basis of the original quenching and tempering process, and the performance of the obtained 42CrMo quenched and tempered steel is improved. It is not obviou...

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Problems solved by technology

[0002] The article "Development of Domestic 42CrMo Quenched and Tempered Steel Crankshaft" in the 2007 No. 6 issue of "Auto Engine" magazine introduced a method to improve the performance of 42CrMo quenched and tempered steel by changing the quenching and tempering temperature of the quenching and tempering process. The method is First fix the quenching temperature and then gradually increase the tempering temperature to obtain 42CrMo quenched and tempered steel with better comprehensive mechanical properties. The disadvantage is that only the quenching and tempering temperature is changed on the basis of the original quenching and tempering process, and the performance of the obtained 42CrMo quenched and tempered steel is improved. It is not obvious that 42CrMo quenched and tempered steel manufactures large structural parts such as crankshafts and bearings, which need to withstand complex working conditions such as bending, torsion, and friction, and is prone to structural damage, resulting in mechanical damage to its components. The performance of quality steel is not significantly improved

[0003] At present, there is a lack of a low-temperature treatment method that can increase the strength and toughness of 42CrMo quenched and tempered steel

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