高碳铬轴承钢网状碳化物的析出规律研究

Study on Precipitation Law of Reticular Carbide in High Carbon Chromium Bearing Steel

为探究高碳铬轴承钢网状碳化物析出规律,本文采用不同温度和不同冷却方式对其进行热处理试验,并对网状碳化物进行组织观察。结果表明:GCr15轴承钢在900℃保温3 h,炉冷后未出现超标的网状碳化物;910~950℃时碳化物主要沿晶界析出,网状碳化物>3级;炉冷条件下,加热温度在910℃以上并不是影响网状碳化物析出的主要原因。GCr15轴承钢在940℃保温3 h,灰冷、炉冷、开炉门冷却和空冷后出现超标的网状碳化物,风冷和水冷后未出现超标的网状碳化物;随着冷却速度的降低,冷却后的网状碳化物越来越严重。网状碳化物的产生必须同时具备“高温”和“慢冷”两个条件。

In order to investigate reticular carbide precipitation behavior of high carbon chromium bearing steel, the heat treatment tests at different temperatures and cooling methods were carried out, and the microstructure of reticular carbides was observed.The results showed that the GCr15 bearing steel had no excessive reticular carbides after furnace cooling at 900 ℃ for 3 h.The carbides mainly precipitated along the grain boundary at 910 ℃ to 950 ℃, and the reticular carbides were more than 3 grades.So the temperature above 910 ℃was not the main reason to affect reticular carbide precipitation under furnace cooling. The GCr15 bearing steel had excessive reticular carbides after ash cooling, furnace cooling, furnace opening door cooling and air cooling, but no excessive reticular carbides after air cooling and water cooling at 940 ℃ for 3 h.With the decrease of cooling rate, the reticular carbide became more and more serious. The formation of reticular carbides must meet the conditions of high temperature and slow cooling at the same time.