焊接工艺对Q345厚板电子束封装淬硬裂纹的影响

Effect of welding process on hardened cracks in electron beam package of Q345 ultra-thick plate

针对Q345特厚板在电子束焊接封装时易产生淬硬裂纹的问题展开分析,探究了焊接工艺对焊缝成形的影响,提出了消除裂纹的有效措施,并测试了不同焊接工艺下焊接接头的力学性能。结果表明:当热输入从7.2 kJ/cm升到9.6 kJ/cm时,裂纹尺寸和数量明显减少,而热输入增加至11.52 kJ/cm时,焊缝表面成形恶化,并在根部产生钉尖缺陷。对于热输入为9.6 kJ/cm的焊接接头,通过焊前预热100℃及焊后缓冷措施,能够完全消除淬硬裂纹。对7.2、9.6 kJ/cm, 9.6 kJ/cm预热+空冷和9.6 kJ/cm预热+缓冷的4种接头进行显微硬度测试,焊缝平均硬度分别为431HV、418HV、369HV和339HV。拉伸试验表明,4种拉伸试样断裂位置皆位于母材,达到了封装质量标准,强度分别为547、543、524和500 MPa。

Aiming at the hardening crack problem of Q345 thick plate in electron beam welding package,the influence of the welding process on the formation of the weld was explored,effective measures to eliminate the cracks were proposed,and the mechanical properties of welded joints under different welding processes were tested.The results show that when the heat input increases from 7.2 kJ/cm to 9.6 kJ/cm,the size and number of cracks significantly decrease.However,when the heat input increases to 1l.52 kJ/cm,the surface formation of the weld deteriorates and nail tip defects occur at the root.For the welded joint with heat input of 9.6 kJ/cm,the hardening cracks can be completely eliminated by preheating 1oo C before welding and slow cooling after welding.The micro hardness test was carried out for the four types of joints with 7.2 kJ/cm,9.6 kJ/cm,9.6 kJ/cm preheating+air cooling and 9.6 kJ/cm preheating+slow cooling.The average hardness of the weld seams are 431HV,418HV,369HV and 339HV,respectively.The tensile test shows that the fracture positions of the four tensile specimens are all located in the base material,and the strength of four welding joint are 547,543,524 and 500 MPa,respectively,which can satisfy the packaging quality standard.