冷却速度对高铬铸铁热处理过程中组织转变的影响.pdf

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Vol, 60 No12
冷却速度对高铬铸铁热处理过程中组织转变的影响
陈闪闪,赵爱民,李振,唐荻
(北京科技大学治金工程研究院,北京100083)
摘要:硏究了冷郝速度对高铬铁热处理冷却过程中其慠观组织转变的影响,并观纂其微观组织。结果表明,在较低
冷速下徹观组织为典型的亚共晶白ロ铸铁組织形态,由初生奥氏体的低温转变組织和共晶休组成;在冷斟速度为3℃?
时开始出飒马氏体组织,并优先在共晶奥氏体区域大量形成;堕着冷却速度的增加,马氏体量逐步增多,在10℃冷
速下为连续的马氏体基体组织和共晶碳化物。二次碳化物在初生戾氏体区大量弥散析出,而在共晶奥氏体区没有二次
碳化物生成。随着冷速的增加,初生奥氏体和共晶奧氏体区的珠光体片层间距均逐漸减
关键词:高铬铁;冷却速度;显微组织;二次碳化物;珠光体片层间距
中图分类号:TG143.9文献标识码:A文章编号:1001-4977(201112-1180-05
Effect of Cooling Rate on Structural Transformation of
High Chromium Cast lron During Heat Treatment
CHEN Shan-shan. ZHAO Ai-min. LI Zhen TANG Di
Research Institute of Metallurgy Engineering, University of Science and Technology Being
Beijing 100083, China)
Abstract: The study was carried out to investigate the effects of cooling rate on structural
transformation of high chromium cast iron during the cooling process of heat treatment. The
microstructure of high chromium cast iron was researched. The results show that the microstructure
is typical hypoeutectic white cast iron at lower cooling rates, which consists of structure transformed
by primary austenite at lower temperature and eutectic; at cooling rate of 3 C/s, martensite begins
to appear, and a large number of martensites are formed preferentially in the eutectic austenite; the
amount of martensite increases gradually with the increase of cooling rate, and its microstructure is
composed of continuous martensite and eutectic carbides at cooling rate of 10 C/s. A large number
of secondary carbides precipitate in the primary austenite region, while no one in the eutectic
austenite region. With the increasing of cooling rate, the interlamellar spacing of pearlite located in
the primary austenite region and eutectic austenite region decreases gradually
Key words: high chromium cast iron cooling rate; microstructure: secondary carbides; interlamellar
spacing of pearlite
高铬铸铁作为第三代耐瘩材料,广泛应用于冶金、理的冷速来控制马氏体组织的转変和二次碳化物的析
矿山、煤炭、电力和建材等工业部门,通过热处理获出显得尤其重要,目前国内外对此方面的报道甚少
得硬度高且彼此狐立分布而不连成?状的MC型共晶
碳化物和连续的马氏体基体织,使其具有较高的1试验材料及方法
磨性和较高韧性的最佳配合到。为获得高的淬透性,
试验用高铬铸铁化学成分如表1所示。采用生铁
通常加入大量合金元素Cr、Mo、u等,使C曲线右废钢、铬铁、锰铁作为原料,在中频感应电炉中熔炼
移,提高马氏体转变开始温度M,获得二次碳化物弥在出炉时加入稀士硅铁合金进行变质处理,采用金属
散分布的全马氏体基体组织。
型浇注成∮90mm鬨球试块,并冷却至室温。用钼丝电
但Cr、Mo价格昂贵,这极大地提高了制造成本。火花切割方法从该高络铸铁试块上切取4mmx10mm
为降低成本,相关研究人员通常采用合理的热处理工.的圆柱试样,进行热膨胀试验,采用德国进口的
艺获得所需性能。因此,通过试验研究热处理过程中DI805A型淬火变形膨胀仪测定试样的膨胀曲线,并
连续冷却速度对高铬铸铁组织转变的影响,以确定合根据膨胀曲线加热阶段和冷却阶段的拐点确定Aa、
收稿日期:2011-05-16收到初稿,2011-08-17收到修订稿
作者简介:陈闪闪(1985-),女,倾士生,主要从事高强度汽车用钢的研发和耐磨材料热处理「艺的研究。E-mail:ziranshanshan@163.com
通讯作者:赵爱民,男,教授,博土生导师,电話:010-62332617