高气压环境脉冲频率对超音频脉冲TIG焊接头焊缝成形和性能的影响

高气压环境会对焊接过程造成很大的负面作用,试验以焊接接头的熔宽、熔深、余高和维氏硬度作为主要评价指标,分析环境压力以及压力环境下脉冲频率对超音频直流脉冲TIG焊接头焊缝成形和性能的影响。结果表明，同一环境压力下,随着脉冲频率的提高,焊缝区的熔宽逐渐减小,熔深逐渐增加;随着脉冲频率的提高,热影响区的宽度和深度随之减小,热影响区的整体尺寸变小,表明超音频直流脉冲TIG焊在高压环境下具有减小热影响区的优势,进而提高焊接接头的质量。焊丝填充区的熔宽和熔深随脉冲频率的提高而减小,余高的整体变化不大,脉冲频率对焊缝余高的影响有限。在同种环境压力下不同脉冲频率得到的焊缝硬度曲线整体趋势相同,硬度值依次按焊缝区—熔合区—热影响区—母材顺序不断降低。随环境压力的提高,焊缝区金属冷却速率加快,焊缝中脆硬组织增加，进而使硬度增大。

Effect of pulse frequency in high pressure environment on weld formation and properties of ultra-high frequency pulsed TIG welding joint

High pressure environment has a great negative effect on welding process.Weld width, penetration, reinforcement and Vickers hardness of welded joint were used as the main evaluation indexes in experiment, influence of ambient pressure and pulse frequency on weld formation and properties of ultra-sonic frequency DC pulse TIG joint was analyzed.Research showed that under the same environmental pressure, as pulse frequency increased, weld width decreased and penetration increased.As pulse frequency increased, width and depth of HAZ decreased accordingly, the overall size of HAZ decreased, which showed that ultrasonic frequency DC pulsed TIG had advantage of reducing heat-affected zone and improving quality of welded joint.Weld width and penetration of filler zone decreased with the increase of pulse frequency, the overall change of reinforcement was not big, and influence of pulsed frequency on reinforcement was limited.The overall trend hardness curves of the weld obtained under different pulse frequencies at the same ambient pressure was the same, and hardness decreased from weld to fusion zone, then to heat affected zone and base metal.With the increase of ambient pressure, cooling rate of weld metal increased, and hardness increased with the increase of brittle-hard structure.