材料期刊网

铁基12％Cr合金(质量分数)常被用来制造先进电机转子.电机转子要求材料具备良好的机械性能和细小的夹杂物,大尺寸的夹杂物通常会使得其性能恶化.本研究在缓冷试验后采用淬火工艺,保留了12％Cr合金液态冷却和凝固过程中形成的夹杂物,并通过扫描电子显微镜和能谱分析对夹杂物的形貌及化学成分进行了分析.结果表明:除各种氧化物夹杂外,在试样中观察到典型的氮化钛夹杂,但冶炼过程中并未添加钛元素.夹杂物析出的热力学计算结果表明:氮化钛夹杂析出于凝固末期,来自原料中痕量的钛元素即可导致氮化钛的析出,而氧化铝夹杂在液态合金中即可生成.通过控制钛元素和氧元素的含量在合理范围,有利于抑制凝固过程的夹杂析出.同时对凝固过程三氧化二钛夹杂析出的可能性进行了研究.

Iron based 12％Cr alloy (mass fiaction) is usually used for advanced electric rotors shaft which require very good mechanical property and fine inclusions,as the large-sized inclusions in the alloy can cause performance deterioration.In this work,quenching process was adopted after slow cooling experiment in order to retain the inclusions precipitated during melt cooling and solidification of 12％ Cr alloy.The morphology and the composition of the inclusions were detected by scanning electronic microscopy (SEM) and energy dispersive spectrometry (EDS),respectively.The results show that besides various shapes of oxide,typical TiN inclusion is found in the sample.However,there is no Ti addition in metallurgical process.Thermodynamic calculation was executed to interpret the inclusion precipitation during solidification and the calculation results indicate that TiN inclusion precipitates at the terminal stage of solidification.Even a trace amount of Ti drawn from raw materials would induce the precipitation of TiN,which would grow into large size and be harmful to alloy property,while the formation of Al2O3 inclusion occurs in liquid alloy.Suggestions for the control of Ti and O are given based on the calculation results,which would be helpful to the production of 12％Cr alloy.The precipitation potential of Ti2O3 inclusion in the experiment has also been discussed by studying the competition of element concentration between Ti and Al.