Influence of the prior athermal martensite on the mechanical response of advanced bainitic steel

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

卷:735

Article

Navarro-Lopez, A.¹  Hidalgo, J.¹  Sietsma, J.¹  Santofimia, M. J.¹ 

[1] Delft Univ Technol, Dept Mat Sci & Engn, Mekelweg 2, NL-2628 CD Delft, Netherlands

关键词: Multiphase steels;    Mechanical response;    Isothermal treatments;    Prior athermal martensite;    Bainitic ferrite;    Strengthening mechanisms;   

DOI  :  10.1016/j.msea.2018.08.047

来源: Elsevier

【 摘 要 】

The accelerated formation of bainite in presence of martensite is opening a new processing window for the steel industry. However, for a feasible industrial implementation, it is necessary to determine the mechanical behaviour of the steels developed under such conditions. This study focuses on analysing the effects of the formation of athermal martensite, followed by the formation of bainitic ferrite, on the mechanical response of a low-C high-Si steel. For this purpose, microhardness measurements and tensile tests have been performed on specimens that were thermally treated either above or below the martensite-start temperature (M-s). Specimens isothermally treated below M-s exhibit a good combination of mechanical properties, comparable with that of the specimens heat treated by conventional treatments above M-s, where there was no prior formation of martensite. Investigations show an increase of the yield stress and a decrease of the ultimate tensile strength as the isothermal holding temperature is decreased below M-s. The formation of prior athermal martensite and its tempering during the isothermal holding leads to the strengthening of the specimens isothermally heat treated below M-s at the expense of slightly decreasing their strain hardening capacity.

【 授权许可】

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