学 术 报 告
讲座主题：Intergranular Fracture and Inverse Bainite in Eutectoid Low Alloy Steels（低合金共析钢沿晶断裂与逆相贝氏体的关系）
报告人：厉雷钧教授，加拿大阿尔伯塔大学化工与材料工程系/加拿大国家焊接中心
时间：2016年12月20日9:00
地点：RAL 411
Abstract：
The evolution of bainite microstructure during isothermal holding is investigated in a Fe-0.84C-1Cr-1Mn steel by dilatometry, microscopy, and thermodynamic calculations. A unique dilatation behavior for isothermal bainite transformation is observed. The dilatation during isothermal hold occurs in two stages, specimen contraction in the early stage followed by expansion during the latter stage of transformation. Through microstructure characterization, an explanation for the observed dilatation is presented. Bainite transformation is initiated by formation of carbide unit from supersaturated austenite following which the bainitic ferrite and the secondary carbides form. Morphology of bainite is identified to be “Inverse Bainite”. The trace of primary carbide nucleation from parent austenite is observable under the microstrucutre as a mid-rib in the bainitc unit. When the transformation time is large enough, the characteristic carbide mid-rib of inverse bainite is no longer present and the microstructure becomes degenerated to upper bainite. The carbide mid-rib is identified to be cementite and the surrounding secondary carbides are identified to be a mixture of cementite and Fe2.xC. The orientation relationship (OR) between individual phases of inverse bainite microstructure is found to obey {111}γ||{221}θ, {110}α||{221}θ {111}γ ||{110}α. The observed intergranular fracture in drop-weight impact tests is thus correlated with the formation of the upper bainite.
报告人简介：
厉雷钧教授分别于华中工学院、西安交通大学及伦斯利尔工学院（Rensselaer Polytechnic Institute）取得学士、硕士及博士学位。长期致力于焊接冶金领域前沿技术研究，在钢铁及合金焊接过程中非平衡相变、组织结构及力学性能研究方向取得了一些得到认可的研究成果。鉴于其对焊接冶金领域的杰出贡献，先后被遴选为美国材料学会会士（ASM Fellow）、美国焊接学会会士（AWS Fellow）及加拿大焊接协会会士（CWA Fellow）。曾任美国材料学会（ASM International）关键焊接技术委员会(Committee on Joining Critical Technologies)主席并连续7年主持MS&T国际焊接学术会议；长期担任Metallurgical and Materials Transactions及Welding Journal编委。为重要国际组织及工业界执笔13份技术报告；于重要国际会议及世界知名大学作大会、主旨及特邀报告23次。
