ステンレス鋼の高輝度・高出力レーザ溶接時の溶融池内湯流れに及ぼす溶接速度の影響の三次元X線透視その場観察法による解明

川人 洋介; 上村 洋輔; 土井 雄一朗; 水谷 正海; 西本 浩司; 川上 博士; 田中 学; 藤井 英俊; 中田 一博; 片山 聖二

doi:10.2207/qjjws.33.13

Elucidation of effect of welding speed on melt flows in high-brightness and high-power laser welding of stainless steel on basis of three-dimensional X-ray transmission in-situ observation

Yousuke KAWAHITO, Yousuke UEMURA, Yuichiro DOI, Masami MIZUTANI, Kouji NISHIMOTO, Hiroshi KAWAKAMI, Manabu TANAKA, Hidetoshi FUJII, Kazuhiro NAKATA, Seiji KATAYAMA

Author information

Yousuke KAWAHITO
Joining and Welding Research Institute, Osaka University
Yousuke UEMURA
Graduate School of Engineering, Osaka University
Yuichiro DOI
Graduate School of Engineering, Osaka University (Present address: Nippon Steel & Sumitomo Metal Corporation)
Masami MIZUTANI
Joining and Welding Research Institute, Osaka University
Kouji NISHIMOTO
Anan National College of Technology
Hiroshi KAWAKAMI
Graduate School of Engineering, Mie University
Manabu TANAKA
Joining and Welding Research Institute, Osaka University
Hidetoshi FUJII
Joining and Welding Research Institute, Osaka University
Kazuhiro NAKATA
Joining and Welding Research Institute, Osaka University
Seiji KATAYAMA
Joining and Welding Research Institute, Osaka University

Keywords: welding speed, melt flows, high-brightness laser welding, stainless steel, three-dimensional X-ray transmission in-situ observation, spatters

JOURNAL FREE ACCESS

2015 Volume 33 Issue 1 Pages 13-19

DOI https://doi.org/10.2207/qjjws.33.13

Details

Abstract

This research was performed with the objective of clarifying the effect of welding speed on melt flows during melt-run welding of SUS304 stainless steel plates with a 6-kW power laser beam on the basis of three-dimensional X-ray transmission in-situ observation. As welding speed increased from 25 mm/s to 250 mm/s, three kinds of welds characterized by porosity formation, no defects or underfilling due to spatters were produced. The average and the maximum values of measured melt flow velocity were three and ten times higher than the welding speed, respectively. Two kinds of circulation flows at the inlet or the tip of a keyhole were confirmed to control heat transfer in a molten pool. It was found that the circulation flows were so sensitive to the welding speed that bubbles resulting in porosity or spatters were often formed. Accoriding to the X-ray observation of the spatters formation with tungsten carbide (WC) tracers, as the melt flow rose along the keyhole wall, the velocity was accelerated from 0.24 m/s to 0.54 m/s near the keyhole inlet. Consequently, the melt flows made the convex surface behind the keyhole grow higher, resulting in spattering.

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