提高高铬铸铁抛丸机叶片寿命的途径

本文对接近共晶成分的20%Cr和17%Cr的高铬铸铁,采用简便的定向凝固铸造工艺和改进的热处理工艺试制抛丸机叶片。在使用钢丸的工况下,所试制叶片的使用寿命达670小时,超过世界名牌产品瑞士GF叶片100%;在使用铁丸的工况下,所试制叶片的使用寿命达380小时,超过国内先进水平的叶片55%。叶片的实际运行试验和磨面分析结果表明,在使用铁丸的工况下,叶片主要是切削磨损,但反复冲击下材料的剥落也起着重要作用,提高叶片的硬度和降低残奥量,有利于耐磨性的提高;在使用钢丸的工况下,叶片的失效主要是由于反复冲击下材料的剥落,而切削所起的作用较轻微,降低残奥量和改善马氏体的韧性能有效地提高耐磨性。碳化物垂直于磨面的定向排列,亦有利于提高耐磨性。

MEASURES OF PROLONGING SERVICE LIFE OF SHOTBLASTER BLADES MADE FR0M HIGH CHROMIUM CAST IRON

By using the chill in the sand mold and the improved heat treatment tech-nology, the superior shotblaster blades are made from high chromium cast ironwith near euteotio composition. Under ~he condition of shooting steel pellets,the service life of this kind of blade is 670 hr., about the double of that ofGF blade made in Switzerland. Under the condition of shooting white ironpellets, the service life of this kind of blade is 380 hr., about 1. 5 times of thatof the domestic high qualily blade. It is shown by trial run and worn surfaceanalysis of the blades that the wear of the blades is mainly caused by micro-cutting in the condition of shooting white iron pellets, but the spalling alsocontributed to wear. Therefore, increasing hardness and decreasing the amountof retained austenite are beneficial to wear resistance of blades. It is alsoshown that the wear of the blades is mainly caused by spalling under the con-dition of shooting steel pellets, and the microcutting has little offect. There-fore, decreasing the amount of retained austenite and improving the toughnessof martensitic matrix give rise to the effective increase of wear resistance ofblades. Unidirectional carbide arrangement perpendicular to wearing surface isalso valuable for the improvement of wear resistance of blades.