TY - JOUR
T1 - Microstructures and mechanical properties of V and/or Nb bearing ultrahigh strength hot stamped steel components
AU - Tateyama, Shota
AU - Ishio, Ryohei
AU - Hayashi, Kouhei
AU - Sue, Tatsuhiro
AU - Takemoto, Yoshito
AU - Senuma, Takehide
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2014
Y1 - 2014
N2 - As a method for producing ultrahigh strength automotive steel components with high gauge accuracy, the hot stamping technology draws attention and the amount of hot stamped automotive components has exponentially increased in the last decade. The concerns about the potential danger of embrittlement and delayed fracture, however, limit the strength of conventional hot stamped components to 1500 MPa. If these concerns are eliminated, automotive steel components with higher strength which is demanded by the automotive industry can be further commercialized. In this study, microstructures and mechanical properties of V and/or Nb bearing ultrahigh strength hot stamped steel components have been investigated. The V addition improves the resistance to delayed fracture by forming VC whose interface with matrix is supposed to act as preferential hydrogen trap site. The Nb addition refines the microstructure, which improves both the toughness and the resistance to delayed fracture. Proper hot stamping conditions for these steels has been discussed to create an ultrafine martensite microstructure and finely dispersed precipitates. The results indicate that 1900 MPa class steel components with good toughness and high resistance to delayed fracture can be produced.
AB - As a method for producing ultrahigh strength automotive steel components with high gauge accuracy, the hot stamping technology draws attention and the amount of hot stamped automotive components has exponentially increased in the last decade. The concerns about the potential danger of embrittlement and delayed fracture, however, limit the strength of conventional hot stamped components to 1500 MPa. If these concerns are eliminated, automotive steel components with higher strength which is demanded by the automotive industry can be further commercialized. In this study, microstructures and mechanical properties of V and/or Nb bearing ultrahigh strength hot stamped steel components have been investigated. The V addition improves the resistance to delayed fracture by forming VC whose interface with matrix is supposed to act as preferential hydrogen trap site. The Nb addition refines the microstructure, which improves both the toughness and the resistance to delayed fracture. Proper hot stamping conditions for these steels has been discussed to create an ultrafine martensite microstructure and finely dispersed precipitates. The results indicate that 1900 MPa class steel components with good toughness and high resistance to delayed fracture can be produced.
KW - Automotive components
KW - Delayed fracture
KW - High strength steel
KW - Hot stamping
KW - Reverse transformation
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U2 - 10.2355/tetsutohagane.100.1114
DO - 10.2355/tetsutohagane.100.1114
M3 - Article
AN - SCOPUS:84906967120
SN - 0021-1575
VL - 100
SP - 1114
EP - 1122
JO - Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
JF - Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
IS - 9
ER -