Microstructures and mechanical properties of TRIP steel produced by strip casting simulated in the laboratory

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:664

Article

Xiong, Z. P.¹  Kostryzhev, A. G.¹  Saleh, A. A.¹  Chen, L.¹  Pereloma, E. V.^1,2 

[1] Univ Wollongong, Sch Mech Mat & Mechatron Engn, Wollongong, NSW 2522, Australia

[2] Univ Wollongong, Elect Microscopy Ctr, Wollongong, NSW 2519, Australia

关键词: Strip casting;    TRIP steel;    Mechanical properties;    Retained austenite;    Isothermal bainite transformation;    Prior austenite grain size;   

DOI  :  10.1016/j.msea.2016.03.106

来源: Elsevier

【 摘 要 】

Conventional transformation induced plasticity (TRIP) steel (0.17C-1.52Si-1.61Mn-0.03Al, wt%) was produced via strip casting technology simulated in the laboratory. Effects of holding temperature, holding time and cooling rate on ferrite formation were studied via analysis of the continuous cooling transformation diagram obtained here. A typical microstructure for conventional TRIP steels consisting of similar to 0.55 fraction of polygonal ferrite with bainite, retained austenite and martensite was obtained. However, coarse prior austenite grain size of similar to 80 mu m led to large polygonal ferrite grain size of similar to 17 mu m, coarse second phase regions of similar to 21 mu m size, small amount of retained austenite (0.02-0.045) and the presence of Widmanstatten ferrite. Optimisation of the microstructure-property relationship was reached via a variation in the isothermal bainite transformation temperature. The highest retained austenite fraction of 0.045 +/- 0.003 with medium carbon content of 1.23 +/- 0.01 wt% was obtained after holding at 400 degrees C, resulting in the highest ultimate tensile strength of 590 +/- 35 MPa and largest total elongation of 0.27 +/- 0.05. The presence of TRIP effect in the studied steel was revealed through the analysis of strain hardening exponent and modified Crussard-Jaoul model. Effect of processing parameters on retained austenite retention and stress-strain behaviour was discussed. (C) 2016 Elsevier B.V. All rights reserved.

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