Effects of rare earth oxide Y 2 O 3 on microstructure and mechanical properties of proeutectoid ferrite/granular bainiti
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Y.F. Zhoua) State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, People’s Republic of China; and College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, People’s Republic of China
Y.G. Zhuo State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, People’s Republic of China; and Environmental Management College of China, Qinhuangdao 066001, People’s Republic of China
J.B. Wang State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, People’s Republic of China
Y.L. Yang College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, People’s Republic of China
Q.X. Yangb) State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, People’s Republic of China (Received 23 December 2015; accepted 11 April 2016)
The effects of rare earth oxide Y2O3 additive on microstructure and mechanical properties of proeutectoid ferrite/granular bainitic coating by flux-cored arc welding were investigated. The results show that the primary austenite in the bainitic coating can be refined by Y2O3. The grain size of primary austenite is decreased from 51.2 lm to 40.1 lm with the increased Y2O3. The size of proeutectoid ferrite is decreased significantly and the fraction of the bainite is increased, which in turn facilitates the uniform distribution of the M/A island. Large number of the dislocation martensite is transformed into M/A. With the increased Y2O3 additive, the hardness and the tensile strength of the coating increases from HV 272 6 13 to HV 312 6 8 and from 764 6 10 MPa to 885 6 12 MPa, respectively. Moreover, the wear resistance of the coating with Y2O3 additive is increased simultaneously.
I. INTRODUCTION
With excellent comprehensive mechanical property, the granular bainite steel is commonly applied for manufacturing large gears, girth-welding pipelines, and bridges.1–3 The outstanding performance of the steel is associated with the microstructure which consists of equiaxed bainitic matrix, martensite (M), and austenite (A). The martensite and austenite structures, which can be recognized as M/A island, contribute a significant improvement for the tensile strength of the steel.4,5 In many cases, the components made up of the granular bainitic gradually lose effectiveness and need Contributing Editor: Jürgen Eckert Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2016.176 1702
J. Mater. Res., Vol. 31, No. 12, Jun 28, 2016
http://journals.cambridge.org
Downloaded: 01 Jul 2016
repairing after being used for a certain period of time.6–10 Several methods can be utilized to restore its working shape, dimension, and properties for the failed component, while the hardfacing method by flux-cored arc welding (FCAW) is one of the best effective ways.11–13 Several investigations have achieved some success in improving the mechanical p
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