论文部分内容阅读
针对热煨弯管的热处理工艺特点,采用Gleeble 3800进行了X100管线钢的连续冷却相变规律研究。利用热膨胀法,结合金相和硬度分析,绘制了X100管线钢的CCT曲线。研究了不同冷却速率对相变温度、组织和硬度的影响。结果表明:随冷却速率的不断提高,组织逐渐从多边形铁素体向准多边形铁素体、粒状贝氏体、贝氏体铁素体转变。冷速为0.1℃/s时,组织为多边形铁素体+少量珠光体;冷速达到50℃/s时,组织为贝氏体铁素体。晶粒尺寸和板条亚结构的细化、切变型组织比例的增加,是硬度随冷速提高而增加的主要原因。
Aiming at the heat treatment process characteristics of hot simmer elbow, the continuous cooling phase transformation of X100 pipeline steel was studied by Gleeble 3800. The CCT curve of X100 pipeline steel was drawn by means of thermal expansion method combined with metallographic and hardness analysis. The effects of different cooling rates on the transformation temperature, microstructure and hardness were studied. The results show that the structure gradually changes from polygonal ferrite to quasi-polygonal ferrite, granular bainite and bainitic ferrite with the increase of cooling rate. When the cooling rate is 0.1 ℃ / s, the microstructure is polygonal ferrite + a small amount of pearlite; when the cooling rate reaches 50 ℃ / s, the microstructure is bainitic ferrite. The grain size and the thinning of the sub-structure of the slab, the increase of the shear-type structure ratio is the main reason that the hardness increases with the increase of the cooling rate.