Effect of austempering parameters on microstructure and mechanical properties of horizontal continuous casting ductile iron dense bars

作     者：Chun-jie Xu Pan Dai Zheng-yang Zhang Zhong-ming Zhang Jin-cheng Wang Yong-hui Liu 

作者机构：School of Materials Science and Engineering Xi'an University of Technology State Key Laboratory of Solidification Processing Northwestern Polytechnical University Shaanxi Hua An Continuous Casting Co.Ltd. 

出 版 物：《China Foundry》 (中国铸造（英文版）)

年 卷 期：2015年第12卷第2期

页      面：104-110页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：financially supported by the fund of the Key Projects of Shaanxi Provincial International Technology Cooperation Plan(2013KW16) the Scientific Research Program funded by Shaanxi Provincial Education Department(2013JK0914) the State Key Laboratory of Solidifi cation Processing in NWPU(SKLSP201115) the Scientific Research Project of Xi'an University of Technology(2013CX004) the fund of the Key Laboratory of Electrical Materials and Infi ltration Technology of Shaanxi Province,China(2014) 

主　　题：horizontal continuous casting (HCC) ductile iron dense bars austempered ductile iron (ADI) microstructure and mechanical properties orthogonal test 

摘      要：In the present research, the orthogonal experiment was carried out to investigate the influence of different austempering process parameters （i.e. austenitizing temperature and time, and austempering temperature and time） on microstructure and mechanical properties of LZQT500-7 ductile iron dense bars with 172 mm in diameter which were produced by horizontal continuous casting （HCC）. The results show that the major factors influencing the hardness of austempered ductile iron （ADI） are austenitizing temperature and austempering temperature. The fraction of retained austenite increases as the austenitizing and austempering temperatures increase. When austenitizing temperature is low, acicular ferrite and retained austenite can be efifciently obtained by appropriately extending the austenitizing time. The proper austmepering time could ensure enough stability of retained austenite and prevent high carbon austenite decomposition. The optimal mechanical properties of ADI can be achieved with the fol owing process parameters： austenitizing temperature and time are 866 ＆#176;C and 135 min, and austempering temperature and time are 279 ＆#176;C and 135 min, respectively. The microstructure of ADI under the optimal austempering process consists of ifne acicular ferrite and a smal amount of retained austenite, and the hardness, tensile strength, yield strength, elongation and impact toughness of the bars are HBW 476, 1670 MPa, 1428 MPa, 2.93%and 25.7 J, respectively.