Elucidation of the 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
2016; Taylor & Francis; Volume: 31; Issue: 3 Linguagem: Inglês
10.1080/09507116.2016.1223204
ISSN1754-2138
AutoresYousuke Kawahito, Yousuke Uemura, Yuichiro Doi, Masami Mizutani, Kouji Nishimoto, Hiroshi Kawakami, Manabu Tanaka, Hidetoshi Fujii, Kazuhiro Nakata, Seiji Katayama,
Tópico(s)Hydrogen embrittlement and corrosion behaviors in metals
ResumoThis 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 to 250 mm/s, three kinds of welds characterized by porosity formation and no defects or underfilling due to spatters were produced. The average and the maximum values of measured melt flow velocity were 3 and 10 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. According to X-ray observation of the formation of spatters with tungsten carbide (WC) tracers, as the melt flow rose along the keyhole wall, the velocity was accelerated from 0.24–0.54 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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