奥氏体变形对耐候钢相变行为及显微组织的影响

在MMS-100热力模拟实验机上采用热膨胀法结合硬度测试,对耐候钢进行了未变形和变形后的连续冷却的实验研究,建立了未变形和变形奥氏体的CCT曲线.利用光学显微镜、扫描电镜分析研究了冷却速度、变形条件对显微组织的影响.实验结果表明,从未变形到变形的过程,多边形铁素体相变开始温度升高,相变区左移,获得铁素体加珠光体混合组织的临界冷速增大.变形奥氏体的位错缠结抑制贝氏体长大,从而细化转变后的显微组织.

Effect of Austenite Deformation on Phase Transformation and Microstructure of a Weathering Steel

Continuous cooling transformation (CCT) curves were plotted for the austenite before and after the compression deformation at 850°C, as a result of an investigation on a weathering steel which was tested on MMS-100 tester by means of dilatometry in combination with Vickers hardmeter. Optical microscope and SEM were employed to investigate the influences of cooling rate and deformation process on the transformation behavior and microstructure. Experimental results showed that in the whole deformation process the starting phase-transformation temperature increases with the polygonal ferrite area moving towards top left corner on the curve diagrams, thus increasing the critical cooling rate of ferrite plus pearlite. The deformed austenite suppresses the growth of bainitic ferrite by its tangled dislocation, then results in the refinement of microstructure.