Mitelea Ion, Bordeașu Ilare, Frant Florin, Uțu Ion-Dragoș, Crăciunescu Corneliu Marius, Ghera Cristian
Department of Materials and Fabrication Engineering, Politehnica University Timisoara, Bulevardul Mihai Viteazul nr.1, 300222 Timisoara, Romania.
Department of Mechanical Machines, Equipment and Transports, Politehnica University Timisoara, Bulevardul Mihai Viteazul nr.1, 300222 Timisoara, Romania.
Materials (Basel). 2023 Mar 23;16(7):2563. doi: 10.3390/ma16072563.
Components made of aluminum alloys operating under cavitation erosion conditions have low performance and therefore a reduced lifetime. The degradation of these components is a consequence of the repetitive implosion of cavitation bubbles adjacent to the solid surface. In this paper, the effect of the rapid re-melting and solidification modification of the surface microstructure of parts of an Al-based alloy strengthened by artificial ageing on the reduction of material loss through cavitation erosion was investigated. The heat source used was the electric arc generated between a tungsten electrode and the workpiece (i.e., TIG). Local surface melting was performed at different values of linear energy (El = 6600-15840 J/cm), varying the current between 100 A and 200 A, at a constant voltage of 10 V. The obtained results showed an increase in the surface microhardness at values of 129-137 HV0.05 and a decrease in the erosion rate from 0.50 µm/min, characteristic of the artificial ageing heat treatment, to 0.10-0.32 µm/min, specific to TIG re-melted layers. For the study of the cavitational erosion mechanism, investigations were carried out by optical microscopy and scanning electron microscopy. The results showed that the improvement of the cavitational erosion resistance by surface melting was a consequence of the increase in microstructural homogeneity and grains refinement.
在空蚀条件下工作的铝合金制成的部件性能较低，因此使用寿命缩短。这些部件的退化是固体表面附近空化气泡反复内爆的结果。本文研究了人工时效强化的铝基合金部件表面微观结构的快速重熔和凝固改性对减少空蚀造成的材料损失的影响。所使用的热源是钨电极与工件之间产生的电弧（即钨极惰性气体保护焊）。在10V恒定电压下，以不同的线能量值（El = 6600 - 15840J/cm）进行局部表面熔化，电流在100A至200A之间变化。所得结果表明，表面显微硬度在129 - 137HV0.05值时有所增加，侵蚀速率从人工时效热处理时的0.50μm/min降至钨极惰性气体保护焊重熔层特有的0.10 - 0.32μm/min。为了研究空蚀机理，通过光学显微镜和扫描电子显微镜进行了研究。结果表明，表面熔化提高抗空蚀性是微观结构均匀性增加和晶粒细化的结果。
