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奥氏体化温度对硼钢淬透性的影响,从实验结果得到,在各种热处理条件下均随温度的提高逐渐降低。氧化及氮化的因素对硼钢淬透性的下降是有一定的影响,但硼原子本身在奥氏体中的分布情况对淬透性的影响是更重要的一个因素。在渗硼试样中观察硼化合物的形成,指出,从高奥氏体化温度直接淬火后,硼的沉淀物是在奥氏体晶界上及晶粒内均匀分布的,但在等温处理、正火处理或慢冷试样中,硼化合物大部份沉淀在奥氏体晶界上。因此,硼钢在高温奥氏体化后失去良好淬透性的原因,可能是由于硼原子从奥氏体晶界上的回扩散作用,使晶界上得不到足够的硼原子降低晶界能,引起硼的效能暂时的消失。
The effect of austenitizing temperature on the hardenability of boron steel, obtained from the experimental results, decreases with increasing temperature under various heat treatment conditions. The factors of oxidation and nitriding have a certain impact on the decrease of hardenability of boron steel. However, the influence of boron atom distribution in austenite on hardenability is a more important factor. The formation of boron compounds was observed in boronizing samples. It was pointed out that the boron precipitates were uniformly distributed on the austenite grain boundaries and within the grains after direct quenching from the high austenitizing temperature. However, in isothermal treatment, In the normalizing or slow cooling samples, most of the boron compounds precipitate on the austenite grain boundaries. Therefore, the reason why boron steel loses its good hardenability after high temperature austenitization may be due to the back diffusion of boron atoms from the austenite grain boundaries, so that insufficient boron atoms can not be obtained on the grain boundaries to lower the grain boundaries Able to cause the performance of boron temporarily disappear.