收藏本站
《International Journal of Minerals Metallurgy and Materials》 2017年09期
收藏 | 投稿 | 手机打开
二维码
手机客户端打开本文

Effect of prolonged isothermal heat treatment on the mechanical behavior of advanced NANOBAIN steel

Behzad Avishan  
【摘要】:The microstructural evolution and consequent changes in strength and ductility of advanced NANOBAIN steel during prolonged isothermal heat-treatment stages were investigated. The microstructure and mechanical properties of nanostructured bainite were not expected to be influenced by extending the heat-treatment time beyond the optimum value because of the autotempering phenomenon and high tempering resistance. However, experimental results indicated that the microstructure was thermodynamically unstable and that prolonged austempering resulted in carbon depletion from high-carbon retained austenite and carbide precipitations. Therefore, austenite became thermally less stable and partially transformed into martensite during cooling to room temperature. Prolonged austempering did not lead to the typical tempering sequence of bainite, and the sizes of the microstructural constituents were independent of the extended heat-treatment times. This independence, in turn, resulted in almost constant ultimate tensile strength values. However, microstructural variations enhanced the yield strength and the hardness of the material at extended isothermal heat-treatment stages. Finally, although microstructural changes decreased the total elongation and impact toughness, considerable combinations of mechanical properties could still be achieved.
【作者单位】Department
【关键词】nano bainite steel prolonged austempering microstructure mechanical properties
【分类号】:TG142.1;TG161
【正文快照】:
as the autotempering phenomenon,which is an unavoidablepart of the bainitic reaction[18].However,the strain ac-commodation accompanied by the shear transformationmechanism of the bainitic transformation results in highdislocation densities,which are resp

中国知网广告投放
 快捷付款方式  订购知网充值卡  订购热线  帮助中心
  • 400-819-9993
  • 010-62791813
  • 010-62985026