Effect of droplet heat content distribution on humping formation in high speed GMAW

Ji CHEN 1,3) and Chuansong WU 1,2) 1) MOE Key Laboratory for Liquid-Solid Structure Evolution and Materials Processing, Institute of Materials Joining, Shandong University, Jinan 250061, China 2) State Key Laboratory for Advanced Welding & Joining, Harbin Institute of Technology, Harbin 150001, China 3) BAM Federal Institute for Materials Research and Testing, Division V.5 Safety of Joined Components, Berlin 12205, Germany

摘 要：The momentum of strong backward flowing melt jet and the thermal action from transferred droplets are two dominating factors affecting the formation of humping bead in high speed gas metal arc welding (GMAW). Appropriate describing the influence of the distribution mode of droplet heat content in the weld pool is essential to understand the physical mechanism of humping bead formation. Based on the experimental results, four kinds of droplet heat content distribution modes are proposed and employed to calculate the transient evolution of the temperature field and weld pool during high speed GMAW process. Through making comparison of predicted and measured weld bead dimensions, a suitable and adaptive distribution mode of droplet heat content is found, i.e., droplet heat content is distributed in bottom layer of gouging region at the front of weld pool, and is averagely distributed in the whole layer at the rear of weld pool. The proposed mode is also validated by experimental observation of the weld pool images and measured by geometric dimensions of the weld bead.

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