Research Of Weld Depth On Laser Overlap-welding Of Thin Steel Sheet

In the stainless steel railway vehicle body, elevator, container, steel furniture ambry and other products, the product surface do not need coating. And the surface quality and tightness will be influenced if using electric resistance welding to weld these parts. However Single-sided molding by partial penetrated laser overlap-welding can compensate for these shortcomings of electric resistance welding, can get good sealing, certain strength and high surface quality.Meanwhile, in the vehicles, ships, aerospace integrated welding fields, a large number of laser overlap-welding parts are three even more layers of thin steel sheet. Electric resistance welding, because of discontinuity and transformative characteristic, especially in welding of three layer board, results in welding deformation, gaps and the mother materials around solder heat affected zone intensity decreases, but adopts continuous laser welding can be avoid these issues.How to get the good welding quality in partial penetrated laser overlap-welding and how to ensure the good welding quality of the three layer board of laser welding, became to the primary problems which needed to solve at present. This article mainly aims at the two important problems to make the following research:First, the partial penetrated laser overlap-welding of SUS304 stainless steel has been imitated by SYSWELD simulation software, and the laser welding heat source model has been established. And then the model was used to simulates and analyzes the influence of laser power and speed to welding temperature field and depth of molten pool. Stress field is also been analyzed.Secondly, the experiment of partial penetration laser welding of thin steel sheet was carried out, using the continuous laser and pulsed modulation laser welding tests. The main influencing factors on partial penetrated laser welding quality were analyzed, including laser power, welding speed, defocus distance, pulse frequency and duty ratio. Then the inspection and analysis of the weld joint after welding was carried out. The contrast analysis of disadvantages on partial penetration welding quality from continuous laser welding to pulse laser welding in partial penetrated laser welding were carried out too.Finally, the orthogonal experiments of zero clearance and tests of variable clearance of three layer board of laser welding were carried out. Through analyze the quality of weld surface and weld section surface, mechanical properties and micro-structure analysis, the influence of welding process parameters and clearance on welding quality of three layer board welding was obtained.