起重机车架用Q345B/HG785D钢板焊接实验研究

以异种钢板Q345B与HG785D端头对焊为研究对象，通过在不同焊接热输入工艺条件下的MAG焊(熔化极活性气体保护电弧焊)，对其端头焊接缺陷、力学性能及组织进行实验研究.实验发现:异种钢板端头对焊中，减小焊接电流可有效提高焊接接头强度;焊前预热、焊后缓冷可减少焊接接头的淬硬组织，提高焊接热影响区韧性.在焊接电流为140~200A、电压为22~24V、焊接速度为28cm/min的热输入条件下，采用预热+后热焊接工艺，焊接接头力学性能和弯曲特性可得到最佳效果.合理的焊接工艺可有效抑制汽车起重机车架焊缝开裂.

Experimental Study on Welding of Q345B/HG785D Steel Plates in Crane Frame

Taking butt welding of dissimilar steel plates of Q345B and HG785D as the object， we studied the welding defects， mechanical properties and microstructures of the welded joint by metal active gas(MAG)arc welding under different heat input conditions. It is found that the strength of the welded joint can be improved effectively by reducing welding current in butt welding of dissimilar steel ends. When the joint is preheated before welding and slowly cool down after welding， the quenched hard area in the microstructure is reduced and the toughness of heat affected zone(HAZ)is increased. Under the heat input conditions of 140-200A welding current， 22-24V welding voltage and 28cm/min welding speed， the mechanical and bending properties of the welded joint can be optimized by the process of preheating and post-heat welding. The optimized welding process can inhibit the weld cracking effectively in crane frame.