ABSTRACT

Friction stir weld joints of 2024-T4 are strengthened by ultrasonic impact treatment (UIT). After ultrasonic impact treatment, the grains on the surface of the sample are refined to form a dense deformation layer, and residual compressive stress is applied on the surface of the sample. The corrosion rate and mass-loss rate of the UIT sample are significantly lower than those of the non-UIT sample, and uniform corrosion is exhibited. The average life of the UIT samples in the air is 1.74 times that of the non-UIT samples; meanwhile, the average life of the UIT samples in 3.5% NaCl solution is twice that of the non-UIT samples. The crack sources of the UIT sample in the air shift from the surface to the subsurface below the strengthening layer, whereas those of the sample in the 3.5% NaCl solution are located in the corroded area on the surface of the sample.

摘要

2024-T4 的搅拌摩擦焊接接头通过超声冲击处理 (UIT) 得到强化。经过超声冲击处理后，试样表面的晶粒细化，形成致密的变形层，并在试样表面施加残余压应力。UIT试样的腐蚀速率和失重率明显低于非UIT试样，呈现均匀腐蚀。UIT样品在空气中的平均寿命是非UIT样品的1.74倍；同时，在 3.5% NaCl 溶液中的 UIT 样品的平均寿命是非 UIT 样品的两倍。空气中 UIT 样品的裂纹源从地表转移到加强层以下的地下，而 3.