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Microstructural characterization and mechanical behavior of ultrasonic impact peened and laser shock peened AISI 316L stainless steel
Surface & Coatings Technology ( IF 5.4 ) Pub Date : 2020-01-24 , DOI: 10.1016/j.surfcoat.2020.125403
Z.D. Wang , G.F. Sun , Y. Lu , M.Z. Chen , K.D. Bi , Z.H. Ni

The effects of ultrasonic impact peening (UIP) and laser shock peening (LSP) on 316L stainless steel were compared in terms of surface morphologies, microstructural evolutions and mechanical properties. The grain refinement mechanisms by mechanical and laser shock wave were subsequently analyzed. Experimental results showed that both UIP and LSP produced micro-grooves with the same depth (~48 μm) at the surface of 316L. The nano-grain size induced by double UIP treatment (10–90 nm) was much smaller than that by triple LSP treatment (>70 nm) because the impact numbers and total impact energy of UIP were much higher. The mechanical twinning was almost complete absence in the sample by UIP. On the contrary, the mechanical twinning was frequently observed in samples by LSP. The magnitude of peak pressure determined the transition from dislocation-dominated mechanism (~680 MPa for UIP) to twinning-dominated mechanism (~2200 MPa for LSP). The resultant dislocation cell size by UIP was much smaller than that by LSP due to the difference of dislocation density caused by different shock wave speed and impact numbers. Additionally, the compressive residual stress on the surface by UIP was higher than that by LSP in both measuring direction. Furthermore, both grain refinement and high dislocation density induced by UIP contributed to a significant increase in the hardness (~433 HV) and yield strength (~447 MPa). By contrast, the LSP induced mechanical twins which can act as dislocation blockers significantly improved the yield strength (~423 MPa).



中文翻译:

超声冲击喷丸和激光冲击喷丸AISI 316L不锈钢的组织和力学性能

从表面形貌,微观组织演变和力学性能方面比较了超声波冲击喷丸(UIP)和激光冲击喷丸(LSP)对316L不锈钢的影响。随后分析了机械和激光冲击波对晶粒的细化机理。实验结果表明,UIP和LSP在316L的表面都产生了深度相同(〜48μm)的微沟槽。两次UIP处理(10-90 nm)诱导的纳米粒度要比三次LSP处理(> 70 nm)诱导的纳米粒度小得多,因为UIP的冲击数和总冲击能高得多。通过UIP,几乎完全没有机械孪晶。相反,LSP经常在样品中观察到机械孪生。峰值压力的大小决定了从位错为主的机理(UIP为〜680 MPa)到孪生为主的机理(对于LSP为〜2200 MPa)的过渡。由于不同的冲击波速度和冲击次数导致的位错密度的差异,UIP产生的位错单元尺寸比LSP小得多。此外,在两个测量方向上,UIP施加的表面压缩残余应力均高于LSP施加的残余应力。此外,UIP引起的晶粒细化和高位错密度均导致硬度(〜433 HV)和屈服强度(〜447 MPa)的显着提高。相比之下,LSP诱导的机械孪晶可充当位错阻滞剂,显着提高了屈服强度(〜423 MPa)。

更新日期:2020-01-24
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