Abstract The effects of ambient pressure on single-pulse laser processing of austenite stainless steel were investigated in this study. The ambient pressure environments were created by Ar gas and ranged from 0.001 bar to 45 bar. It is observed that the ejection and expansion of the metal vapor are severe under a low pressure and gradually become limited with the increase of ambient pressure. Numerous oxides remain on the molten-pool surface under a low pressure, and a shiny solidified molten-pool surface without oxides can be obtained when the pressure is higher than 10 bar. Furthermore, the ripples induced by the ejection of the metal vapor were detected on the solidified molten-pool surface, and it significantly reduced with the increase in ambient pressure. Larger aspect ratios of molten pools were obtained under higher pressures, and a tendency wherein the primary dendrite arm spacing and grain size decrease with the increase of ambient pressure was observed. When the ambient pressure changed from 0.001 bar to 45 bar, the aspect ratio increased by approximately 12%, the dendrite arm spacing decreased approximately 12% and 4% on the side and center positions, respectively, and the grain size decreased approximately 37%.

中文翻译：

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环境压力对奥氏体不锈钢单脉冲激光加工的影响

摘要 研究了环境压力对奥氏体不锈钢单脉冲激光加工的影响。环境压力环境由 Ar 气体创建，范围从 0.001 巴到 45 巴。观察到金属蒸气的喷出和膨胀在低压下剧烈，随着环境压力的增加而逐渐受限。在低压下，熔池表面会残留大量氧化物，当压力高于10巴时，熔池表面可以得到光亮的固化熔池表面，没有氧化物。此外，在凝固的熔池表面检测到金属蒸气喷射引起的波纹，随着环境压力的增加，波纹显着减小。在更高的压力下获得更大的熔池纵横比，并且观察到随着环境压力的增加，一次枝晶臂间距和晶粒尺寸减小的趋势。当环境压力从 0.001 bar 变为 45 bar 时，纵横比增加约 12%，侧面和中心位置的枝晶臂间距分别减少约 12% 和 4%，晶粒尺寸减少约 37%。