中碳车轮钢中MnS-Al_(2)O_(3)复合夹杂物的研究

Study on the composite inclusions of MnS-Al_(2)O_(3)in wheel steel

高速车轮钢中的MnS-Al_(2)O_(3)复合夹杂物能够降低Al_(2)O_(3)夹杂物对于车轮钢疲劳性能的危害。通过检测实验室制备的车轮钢,确定了车轮钢中存在MnS夹杂物、Al_(2)O_(3)夹杂物和MnS-Al_(2)O_(3)复合夹杂物。采用酸溶法提取Al_(2)O_(3)夹杂物,根据XRD检测结果确定钢中Al_(2)O_(3)夹杂物的晶体类型为α-Al_(2)O_(3)。通过非水溶液电解法提取了钢中的复合夹杂物,并检测MnS-Al_(2)O_(3)复合夹杂物的形貌。根据钢的成分进行热力学计算,分析试验钢的固相线和液相线温度和夹杂物析出温度的关系,表明车轮钢中Al_(2)O_(3)夹杂物能够为MnS的析出提供形核条件。最后,通过计算MnS-Al_(2)O_(3)复合夹杂物界面两相的晶面错配度,说明了MnS的(100)面在Al_(2)O_(3)(0001)面上可以有效形核析出。这为钢中形成MnS-Al_(2)O_(3)复合夹杂物,降低Al_(2)O_(3)夹杂物危害提供了一定的理论基础。

The composite inclusions of MnS-Al_(2)O_(3)in high-speed railway wheel steel can reduce the effect of Al2O3 on fatigue properties of wheel steel.In this study,the types of inclusions in wheel steel were determined as MnS,Al_(2)O_(3)and MnS-Al_(2)O_(3)composite inclusions by testing wheel steel prepared in laboratory.The inclusions of Al_(2)O_(3)were extracted by acid dissolution method.XRD results showed that crystal texture of Al_(2)O_(3)inclusion in steel wasα-Al_(2)O_(3).The composite inclusion in steel was extracted by non-aqueous electrolysis method,and the morphology of MnS-Al_(2)O_(3)composite inclusion was detected.Based on the thermodynamic calculation of steel composition,the relationship between the solidus and liquidus temperatures of experimental steel and the precipitation temperature of inclusions was analyzed.The results show that Al_(2)O_(3)inclusions in wheel steel can provide nucleation sites for the precipitation of MnS.It was clarified that the surface of(100)of MnS can precipitate on the Al_(2)O_(3)(0001)through the calculation of the mismatch between the two phases of MnS and Al_(2)O_(3).This works provides a theoretical basis for the formation of MnS-Al_(2)O_(3)composite inclusions in steel and the reduction of the damage of Al_(2)O_(3)inclusions.