Clarification of High-Efficiency, Deep-Penetration Welding Mechanism with High-Brightness Laser under Partial, Low-Vacuum Atmosphere

深熔是激光焊接的一个重要优势。本研究旨在阐明高效率深熔焊接的机理，包括焊接性、激光诱导羽流的光学特性以及部分低真空气氛下高亮度激光熔池中的小孔行为。穿透深度是101kPa时的2.5倍以上。当周围气压为101~0.1kPa时，激光诱导的羽流引起的入射激光的折射率急剧降低。X射线高速观察表明，小孔不稳定，但没有形成孔洞。

Deep penetration is an important advantage in laser welding. This study was undertaken in order to clarify high-efficiency, deep-penetration welding mechanism including weldability, optical characteristics of laser-induced plume and keyhole behaviors in molten pool with brightness laser under partial, low-vacuum atmosphere. The penetration depths were over 2.5 times as deep as those obtained at 101 kPa. Refraction of incident laser caused by laser-induced plume was drastically reduced corresponding to surrounding pressure of 101 to 0.1 kPa. X-ray high-speed observation revealed that keyhole is unstable but porosity is not formed.