超厚爆炸复合板覆层裂纹分析

Analysis of cracks in cladding of ultra-thick composite plate

针对超厚爆炸复合板在卷制过程中覆层产生裂纹的情况,通过对复合板试样进行金相观察,确定裂纹源产生于复合板结合面。通过微观金相及硬度分析,复合板覆层产生裂纹的原因主要是复合板爆炸焊参数设计不佳,其结合面强度、韧性均较低,并且超厚板材在复合后的校平过程中校平次数增多、压力增大,导致复合板结合面覆层侧存在尺寸较大的裂纹、空洞缺陷,且缺陷较为集中,裂纹向多方向扩展。另外,复合板经爆炸复合后热处理参数设计不佳,导致复合板结合面覆层硬度值远高于基层和覆层处硬度值。

During the rolling of ultra-thick composite plate,cracks are found in the cladding.Through the metallographic test,it is determined that the crack source comes from the joining surface.Through the microscopic metallographic and hardness test of the joining surface,it is analyzed that the reason of the crack source on the joining surface of the composite plate and the cracks in cladding caused by crack sources during the rolling is mainly due to insufficient explosion parameter design of the composite plate,both the strength and toughness of the joining surface are low,and the times of leveling and pressure of ultra-thick during the leveling increase,which leads to large cracks and cavity defects in the cladding on the joining surface,and the defects relatively concentrate,and the cracks expand in multiple directions;in addition,the design of heat treatment parameters after explosive is insufficient,which causes the hardness of the cladding on the joining surface is much higher than that of the base metal and the cladding.