In Situ Neutron Diffraction during Thermo-Mechanically Controlled Process in Low Alloy Steels
In Situ Neutron Diffraction during Thermo-Mechanically Controlled Process in Low Alloy Steels
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DOI：
10.4028/www.scientific.net/ssp.118.419
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发表时间：
2006-12
期刊：
影响因子：
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通讯作者：
M. Koo;Pingguang Xu;J.H. Li;Y. Tomota;O. Muránsky;P. Lukas;Y. Adachi
中科院分区：
文献类型：
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作者：
M. Koo;Pingguang Xu;J.H. Li;Y. Tomota;O. Muránsky;P. Lukas;Y. Adachi
提出了一种利用中子衍射原位研究形变热控工艺（TMCP）过程中微观组织演变的方法。由于中子束太弱，无法实现时分测量以跟踪低碳钢中的快速转变，因此添加2%Mn以使奥氏体向铁素体的转变较慢。用电阻法将圆棒试样加热至900°C，然后冷却至700°C，并压缩25%，随后逐步冷却。在步进冷却过程中，获得了中子衍射剖面，并分析了铁素体的体积分数、相应力和半高宽。使用类似的TMCP模拟器，试样在加热程序的几个阶段淬火到水中，以冻结相应的显微组织，用OM和SEM观察。结果表明，冷却时中子衍射法测定的铁素体体积分数与显微镜法测定的铁素体体积分数吻合较好。结果表明，奥氏体变形和Nb的加入促进了铁素体相变，晶粒细化。
A challenge was made to examine the micro-structural evolution during thermomechanically controlled processing (TMCP) by in situ neutron diffraction. Since the neutron beam is too weak to achieve a time-division measurement to follow a rapid transformation in alow carbon steel, 2%Mn was added to make the austenite to ferrite transformation slower. Round bar specimens were heated up to 900°C with an electrical resistance method, then cooled down to 700°C, and compressed by 25% followed by step-by-step cooling. During the step-by-step cooling, neutron diffraction profiles were obtained and the volume fraction of ferrite, phase stresses and FWHM were analyzed. Using a similar TMCP simulator, specimens were quenched into water at several stages of the heat schedule to freeze the corresponding microstructures, which were observed with OM and SEM. As results, the ferrite volume fraction determined by neutron diffraction on cooling agrees well with that by microscopy. It is found that the austenite deformation and/or Nb addition accelerate the ferrite transformation to result in finer grain size.