Microstructure evolution and enhanced performance of a novel Nb-Mo microalloyed medium Mn alloy fabricated by low-temperature rolling and warm stamping

Autor: Minghui Cai, Bin Zhu, Hua Ding, Yisheng Zhang, Hongshou Huang, Haijun Pan, Yilin Wang
Rok vydání: 2017
Předmět:
Zdroj: Materials & Design, Vol 134, Iss, Pp 352-360 (2017)
ISSN: 0264-1275
DOI: 10.1016/j.matdes.2017.08.047
Popis: A combined low-temperature rolling and warm stamping process was proposed for a Fe-5.6Mn-0.19C-1.2Al-0.05Nb-0.22Mo alloy to improve the tensile ductility and surface quality of the stamped parts. The results show that the present warm-stamped U-shaped parts exhibited the relatively uniform ultrafine multiphase microstructure and desirable mechanical properties, e.g. the average products of ultimate tensile strength and total elongation (PSE) values reached 27.5–31.3 GPa·%, which are more than double or triple times higher than those of the hot-stamped boron steels with similar strength level. As the stamping temperature decreased from 760 to 700 °C, both the fractions of ferrite and austenite increased, resulting in the enhanced tensile ductility (up to 24.5%) with sacrificing tensile strength from 1717 ± 117 to 1424 ± 53 MPa. The difference in stamping temperature greatly affected the tensile deformation behavior of the stamped parts: at 700 °C, the tensile curves exhibited Lüders band propagation (LBP) behavior, and both Portevin-Le Chatelier (PLC) and transformation induced plasticity (TRIP) effects happened, while at 760 °C, the tensile curves exhibited continuous yielding behavior, and only TRIP effect happened over the entire plastic deformation. Keywords: Medium manganese steel, Warm stamping, Low temperature rolling, Microstructure, Mechanical properties
Databáze: OpenAIRE
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