预热对水泥卧辊磨辊身堆焊层硬度和裂纹倾向的影响

Effect of preheating on hardness and cracking tendency of wear resistant layer of horomill

使用QG系列焊条对水泥卧辊磨辊身进行耐磨堆焊修复,由于母材和焊条的碳当量较高,故需在焊前进行合理的预热并在焊后进行缓冷。根据母材和焊条碳当量选择了200℃、300℃和400℃三种预热温度,比较和分析了在不同预热温度下堆焊出的QG-3和QG-4两种耐磨工作层的裂纹倾向、宏观硬度和显微组织。使用着色渗透探伤法检测耐磨工作层的裂纹情况,发现QG-3工作层预热至300℃以上不产生裂纹,QG-4工作层预热至200℃以上不产生裂纹。测试耐磨工作层的硬度,发现随着预热温度的升高,QG-3和QG-4两种工作层的宏观硬度均下降。分析显微组织,发现这是由于QG-3工作层中硬质相(Fe,Cr)_7C_3和QG-4工作层中马氏体减少引起的。

When the horomill was repaired with QG welding rod,it is necessary to preheat Horomill before hardfacing and slowly cool it down after hardfacing because of the high carbon equivalent of base metal and welding rod. According to carbon equivalent of base metal and welding rod, the preheating temperature is chosen as 200℃, 300℃ and 400℃, then the cracking tendency, hardness and mierostructure of the two wear resistant layers of QG-3 and QG-4 at various preheating temperature were compared and analyzed. T cracking degree of wear resistant layers was tested with dye penetrant inspection, it is found that there is no crack in wear resistant layer of QG-3 when the preheat temperature is higher than 300℃ and no crack in QG-4 when the preheat temperature is higher than 200℃. Results of hardness test showed that the hardness of both the wear resistant layers decrease with the preheat temperature rising,which are caused by reduction of (Fe, Cr)_7 C_3 in QG-3 and martensite in QG-4.