高碳钢和铸铁渗硼工艺的研究

Study on Boronizing Process for High Carbon Steel and Cast Iron

采用表面预先脱碳,随后渗硼的方法对T8钢、GCr15钢及铸铁的渗硼过程及渗硼后组织和性能进行了试验研究。试验表明,与直接渗硼法相比,经预脱碳再渗硼能提高渗硼速度及渗层硬度。T8钢渗硼层前沿的碳分布均匀;试样上出现裂纹时的抗压强度提高57%左右。GCr15钢脱碳过程比T8钢缓慢,在渗硼层中可观察到铬的重新分布及氧化物。灰口铸铁和球墨铸铁经预脱碳处理后,硼化物中石墨夹杂含量明显降低,提高了渗硼层与基体的结合力。与直接渗硼相比其耐磨性提高了3～5倍。

Boronizing treatment with pre-decarburizing of surface of high carbon steels and cast irons and boronized microstructure and mechanical properties were investigated. Experimental results showed that boronizing with pre-decarburizing of surface can accelerate boronizing and flat distribution of the boride layer, well distribution carbon in the region at front of the boride layer in specimens of steel T8 was formed. Its compression strength appearing first crack on the surface of the specimens is raised by nearly 57% under the condition of boronizing at 940℃ for 4h as compared with that of gained from direct boronizing treatment. The rate of decarburizing of steel GCr15 is lower then that of steel T8, concentration of chromium and its oxides in boride layer were observed. After boronizing with pre-decarburizing of grey and spheroidal-graphitic cast iron the content of graphite in boride layer decrecased and cohesive strength between boride layer and matrix increased, the wear resistance of boride layer enhanced 3～5 times as compared with that gained from direct boronizing of cast iron.