为解决大直径刀盘拼装焊接后残余应力大、产生延迟裂纹的问题，提出通过控制预热温度提高堆焊质量的方案。试验采用自保护药芯焊丝对盾构刀盘使用的Q345R材料进行堆焊，分别研究预热温度为50、100、150、200 ℃时堆焊组织和性能的变化。结果表明：
经过100 ℃预热后，残余应力最小，冲击韧性最好，显微硬度梯度变化幅度最小，综合力学性能最佳。将试验得出的结论用于指导刀盘堆焊时预热温度的选取，证明通过选取合适的预热温度，刀盘焊接后UT探伤结果一次合格率达到100%，在实际应用中取得了良好的效果。
Large residual stress and delayed crack would be
produced after assembly and welding of largediameter cutterhead, hence,
the scheme of improving the surfacing welding quality by controlling preheating
temperature is put forward. The selfprotecting flux
cored wire is used to weld the shield tool plate by material Q345R, and the
variations of surfacing welding structure and performance at the preheating
temperature of 50, 100, 150 and 200 ℃ are studied
respectively. The results show that after preheating by 100 ℃, the residual stress is the least, the impact toughness is the
best, the microhardness gradient variation is the least, and the comprehensive
mechanical property is the best. The conclusions obtained by the test are used
to guide the selection of preheating temperature for surfacing welding of the
cutterhead. It has been proved in practice that by selecting the appropriate
preheating temperature, the onetime pass rate of UT
flaw detection results after welding of the cutterhead reaches 100%, and good
results have been achieved in practical application.
