Cause analysis of carburizing quenching cracks of sun gear

doi:10.13251/j.issn.0254-6051.2023.09.050

Abstract

Abstract: After carburizing and quenching, tooth cracks occurred in the sun gears of mining reducer, causing the products to be scrapped due to the deep cracks. In order to analyze the failure cause of the sun gear, the raw materials, heat treatment process, microstructure, grain size, and macro and micro morphological characteristics of the cracks were analyzed and discussed. The results show that the chemical composition of the material used for the sun gear conforms to the standard of the 18CrNiMo7-6 steel, and the cracks in the sun gear are typical intergranular quenching ones, the main reason of which is related to the coarse grain size. The coarse grains are not caused by the existing late heat treatment, but are mainly related to the improper heating temperature or forging process in the early process stages.

Key words: sun gear, 18CrNiMo7-6 steel, carburizing and quenching, cracks, cause analysis

CLC Number:

TG157

Zhang Lei, Mi Pei, Ma Chunliang, Sun Yongpeng. Cause analysis of carburizing quenching cracks of sun gear[J]. Heat Treatment of Metals, 2023, 48(9): 293-296.

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