基于焊缝微观组织形态控制的超声辅助钨极氩弧焊热裂纹抑制方法研究

项目名称： 基于焊缝微观组织形态控制的超声辅助钨极氩弧焊热裂纹抑制方法研究

项目编号： No.51205218

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 机械工程学科

项目作者： 李一楠

作者单位： 青岛理工大学

项目金额： 26万元

中文摘要： 为解决紫铜厚大结构件钨极氩弧焊（GTAW）工艺中热裂纹严重的问题，本项目提出超声辅助GTAW新工艺。利用超声波的空化作用和声流作用，对焊接过程中脆性温度区间（BTR）内半固态焊缝金属微观组织形态及分布规律进行控制，有效抑制紫铜厚大结构件焊接热裂纹，获得焊缝金属组织细密均匀的焊接接头，提高焊缝性能。实现厚大结构件不预热焊接，有效降低焊接工艺难度，提高生产效率。着重研究超声辅助GTAW工艺中超声的空化作用及声流作用对焊缝金属晶粒细化的作用机制，研究晶粒细化对热裂倾向及焊缝金属力学性能的影响规律。建立超声辅助GTAW时BTR内半固态焊缝金属的流变模型，研究半固态中液相的填充"愈合"作用对热裂纹的抑制效果及作用机理。基于刚性拘束热裂纹实验，建立具有热裂成因分析能力及热裂倾向预测能力的紫铜厚大件GTAW热力耦合模型，优化并完善超声辅助GTAW工艺，为获得厚大结构件的无热裂纹焊接探索一条新的技术途径。

中文关键词： 超声辅助钨极氩弧焊；紫铜；热裂纹；晶粒细化；动力学分析

英文摘要： To solve the bottleneck of serious hot cracking in Gas Tungsten Arc Welding (GTAW) of large dimension copper structures, a new process of ultrasonic assisted GTAW is proposed. Using the cavitation and acoustic streaming effects of ultrasonic, the microstructures and distribution rules of the semi-solid state weld metals in the brittle temperature range (BTR) can be controlled.This process can suppress the hot cracking effectively in welding of large dimension copper structures and obtain fine microstructure of welding joints. Moreover, this process has advantages in improving the performance of the welds and increasing production enficiency without preheating. The emphases of this project are to research the mechanism of weld metal grain refinement under the condition of cavitation and acoustic streaming effects of ultrasonic acting. And influence rules of grain refinement phenomenon on the hot cracking tendency and welds mechanical properties. Establish the rheological model of semisolid weld metal in the BTR when using ultrasonic assisted GTAW process to research the "healing" effects of the liquid phase in the semisolid weld metal, and inherence mechanism of "healing" effects for suppressing the hot cracking. Based on the rigid restraint hot cracking test, a thermal-stress coupled model can be established, wh

英文关键词： ultrasonic assisted GTAW；copper；hot cracking；grain refinement；dynamic analysis