等温淬火对连铸球铁型材组织和硬度的影响  

Effect of austempering processing parameters on microstructure and hardness of nodular cast iron dense bar

作　　者：王锦程[1] 李伟明[2] 张忠明[1,2] 徐春杰[2] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072 [2]西安理工大学材料科学与工程学院,陕西西安710048

出　　处：《材料热处理学报》2013年第1期70-75,共6页Transactions of Materials and Heat Treatment

基　　金：西北工业大学凝固技术国家重点实验室开放课题(SKLSP201002);陕西省重点学科建设专项资金资助项目(陕财办教2008-171)

摘　　要：为了探寻水平连铸球墨铸铁QT500-7型材的最佳等温淬火工艺,运用正交试验方法对奥氏体化温度和时间、等温淬火温度及时间等工艺参数进行优化分析,研究不同工艺参数下该型材的组织及硬度的变化规律。结果表明,等温淬火温度和奥氏体化温度是影响合金硬度的主要因素,随着二者温度的升高,基体组织中残留奥氏体量增多,硬度逐渐减小。试验用型材在现有的热处理参数中,硬度最高的工艺为840℃×60 min奥氏体化+280℃×100 min等温淬火,在此工艺条件下可以得到由细密贝氏体型铁素体与少量残留奥氏体组成的组织,型材硬度为476 HBW。In order to find the optimum austempering process parameters for QT500-7 nodular cast iron dense bar produced by horizontal continuous casting（HCC） , the orthogonal experiment was used to optimize the parameters, i. e austenitizing temperature, austenitizing time, austempering temperature and austempering time, according to the microstructure and hardness of the dense bar. The results show that the major factors influencing hardness of the austempered nodular cast iron dense bar are austempering temperature and austenitizing temperature. As the temperatures increases, the fraction of retained austenite increases and the hardness discreases. The highest hardness of the austempered QT500-7 dense bar is obtained by using following process parameters： austenitizing temperature and austempering temperature are 840 ℃ and 280 ℃, and austenitizing time and austempering time are 60 min and 100 min, respectively. The mierostructure of the dense bar under the optimum austempering process is composed of thin acicular ferrite and retained austenite, and the hardness is 476 HBW.

关 键 词：水平连铸 球墨铸铁 等温淬火 正交试验 

分 类 号：TG143.5[一般工业技术—材料科学与工程]