表面强化处理对工业纯钛焊接接头电化学腐蚀性能的影响

Effect of Surface Strengthening Treatment on Electrochemical Corrosion Properties of Industrial Pure Titanium Welded Joints

摘要:

为了改善焊接接头的性能,延长其使用寿命,实验采用喷丸强度为0.15A的超声喷丸处理(USSP)方式对工业纯钛TA2焊接接头进行强化。通过OM、SEM、TEM分别对TA2焊接接头各区域组织及腐蚀形貌进行观测,对不同工艺处理试样的残余应力值、表面粗糙度进行了测定,并对超声喷丸后试样表面进行热处理和表面打磨,研究了不同表面残余应力及表面粗糙度对焊接接头焊缝区域在80℃ 的10% HCl溶液中的电化学腐蚀性能。结果表明,USSP强化处理纯钛焊接接头耐腐蚀性能有所提升。经退火处理后,随着退火时间的增加,耐腐蚀性能先增加后降低,退火0.5h时,自然腐蚀电位最高,电流密度最低,耐腐蚀性能最优。经表面打磨处理,腐蚀速率主要由扩散步骤控制,产生浓差极化,随着打磨强化层的增加,扩散速率加快,耐腐蚀性能有提高。打磨至强化层2/5处时,耐腐蚀性能提升明显。

Abstract:

In order to improve the performance of the welded joint and prolong its service life, the industrial pure titanium TA2 welded joint was strengthened by ultrasonic shot peening (USSP) with a shot peening strength of 0.15A. The microstructure and corrosion morphology of TA2 welded joints were observed by OM, SEM and TEM. The residual stress values and surface roughness of different treated samples were measured, the surface of the samples after ultrasonic shot peening were heat treated. And surface grinding, the electrochemical corrosion performance of different surface residual stress and surface roughness on the welded joint weld zone in 80 ° C 10% HCl solution was studied. The results show that the corrosion resistance of the USSP intensive treatment of pure titanium welded joints has been improved. After annealing, the corrosion resistance first increases and then decreases with the increase of annealing time. When annealing for 0.5h, the natural corrosion potential was the highest, the current density was the lowest, and the corrosion resistance was optimal. After surface grinding, the corrosion rate is mainly controlled by the diffusion step, resulting in concentration polarization. As the polishing strengthening layer increases, the diffusion rate increases, and the corrosion resistance has been improved. When polished to 2/5 of the strengthening layer, the corrosion resistance has been improved significantly.