A cryogenic treatment method for improving the dimensional stability of gcr15 steel

Abstract

The invention discloses a cryogenic treatment method for improving dimensional stability of GCr15 steel. The method comprises the following steps of: cooling a GCr15 material after quenching to -80 DEG C- -100 DEG C at the rate of 2-5 DEG C / min, performing heat preservation for 0.5h-1h, continuously cooling to -180 DEG C- -190 DEG C after the end of heat preservation, and performing heat preservation for 2h-3h; and continuously heating to room temperature at the rate of 2-5 DEG C / min after the end of heat preservation, performing heat preservation for 0.5h-1h, and finally performing a normal tempering process, thereby ending the process. As for the GCr15 steel after treatment through the method disclosed by the invention, the surface hardness of the material is improved by 1.5HRC, and the dimensional variation ratio of an opening of a circular ring is obviously smaller than that without cryogenic treatment; and simultaneously, along with the prolongation of the opening time, the opening of the circular ring after cryogenic treatment has smaller fluctuation in the dimensional variation ratio of the opening of the circular ring and is more stable.

Description

technical field [0001] The invention relates to the technical field of cryogenic treatment and heat treatment, in particular to a cryogenic treatment method for improving the dimensional stability of GCr15 steel. Background technique [0002] GCr15 steel is a common high-chromium bearing steel with high hardenability and superior comprehensive performance after heat treatment. GCr15 steel is often used for shaft parts such as machine tool spindles. After normal quenching and tempering treatment of GCr15 steel parts, a certain amount of residual austenite generally remains on the martensite matrix. Generally, martensite in the quenched structure accounts for more than 80%, uniformly distributed fine carbides account for 5% to 10%, and retained austenite accounts for about 9% to 15%. Since retained austenite is a metastable phase, when the stable condition is broken, it will decompose or transform from face-centered cubic austenite to body-centered cubic martensite. The diff...

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Problems solved by technology

Therefore, when the size of the finished parts changes during storage or use, the dimensional accuracy of the shaft parts will be reduced, especially after the dimensional stability of the shaft parts for machine tools is reduced, which seriously affects the machining accuracy of the machine tool, or even scrapped

At present, there is no report on how to improve the dimensional stability of GCr15 steel materials

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