S含量对高速车轮钢断裂韧性影响的研究

STUDY OF THE EFFECT OF SULFUR CONTENTS ON FRACTURE TOUGHNESS OF RAILWAY WHEEL STEELS FOR HIGH SPEED TRAIN

研究了S含量对高速车轮钢断裂韧性的影响.结果显示,适当提高车轮钢中的S含量,可以有效提高断裂韧性.对夹杂物的分析表明,S含量为0.001%(质量分数)的车轮钢中Al_2O_3和Al_2O_3+(Ca,Mg)O的氧化物夹杂相对较多,而MnS夹杂物较少.在相近的O含量水平下,将S含量从0.001%提高到0.006%,车轮钢中夹杂物形态发生变化,主要形成MnS包裹在Al_2O_3表面的复合夹杂物.断裂韧性的提高与夹杂物种类和形态的变化有关.应用镶嵌应力理论分析表明,MnS包裹在Al_2O_3表面后,相比于单独Al_2O_3夹杂物,可改善复合夹杂物周围的应力集中,从而改善断裂韧性.

The effect of sulfur contents on fracture toughness of railway wheel steels for high speed train was investigated.The results show that,with the same production process,sulfur content increase to some extent in wheel steels resulted in a great improvement in fracture toughness.The analysis of non-metallic inclusions revealed that,in the steel with sulfur content of 0.001%,a large amount of Al_2O_3 and complex Al_2O_3＋（Ca,Mg）O inclusions were found,while MnS inclusions were rarely observed.When S content was increased from 0.001%to 0.006%,the type and morphology of inclusions were changed,MnS inclusions with core of Al_2O_3 were often observed and naked oxide inclusions were seldom found.This investigation shows that the fracture toughness improvement were closely associated with the type and morphology of inclusions due to sulfur content variation.The calculation showed that,with a cover of ductile MnS,stress concentration around complex inclusions decreased,which contribute to toughness improvement.