Study On The Surface Flow Behavior Of TIG Weld Pool

With the further development of industrial level of society, the pursuit of welding technology with high efficiency, high quality level is attracting more and more attention. Improving the welding speed, optimization of filling materials classification can effectively satisfy the industrial development demand, but with the increase of welding speed, molten pool flow behavior became more acute, at the same time, the welding material of complicated components will also cause the molten pool flow behavior to be more complicated. Flow behavior of molten pool could directly affect the weld forming macro, micro morphology, element diffusion migration, dilute alloy elements and so on, these will be crucial influences on the performance of the weld joint, therefore, the study of welding molten pool flow behavior is of great significance.In this paper, in order to explore the molten pool flow behavior, with TIG welding for welding process test method, using visual particle tracking as the research main line. Based on the main line, set the molten pool laser reflection visualization study platform and build the platform. On the basis of the molten pool the flow behavior of 304 stainless steel and Q235 carbon steel were studied. Further explores the dissimilar metal weld molten pool flow behavior, the selection of 304 stainless steel/Q235 carbon steel, 316 L stainless steel/Q235 carbon steel, 304 stainless steel /316 L stainless steel three different kinds of dissimilar steel welding molten pool flow as the testing objects. Based on image processing method, the flow rate on the surface of molten pool is quantitatively calculated. In order to better experiment data post-processing, accurately extract the 304 stainless steel TIG welding molten pool edge. The research content is as follows:1. Based on the building of the molten pool laser reflection platform, the tracer particles have been 304 stainless steel and Q235 carbon steel for general pulse TIG welding respectively, based on the principle of the pixel coordinates experiment to process the data collected, 304 stainless steel and Q235 carbon steel weld pool surface tracer particle trajectory, to characterize the surface of the liquid metal molten pool flow field, the results showed that: 304 stainless steel TIG welding when the tracer particles by molten pool edge counterclockwise movement into the center of molten pool, this shows that the molten pool on the surface of the liquid metal by the molten pool to counterclockwise around the way into the center of the molten pool; Q235 carbon steel TIG welding when the motion process of tracer particles basic direction and not always on the edge of the pool, which suggests that Q235 carbon steel in TIG welding, the molten pool on the surface of the liquid metal is not directional and irregular edge of trajectory flow to the molten pool eventually. Through actual molten pool width and molten pool pixel width of the mapping relation, get the tracer particles on the surface of the molten pool, the actual movement distance, obtained 304 stainless steel TIG welding on the surface of the molten pool flow speed is about 10-15 mm/s, Q235 TIG when welding on the surface of the molten pool flow velocity is about 10-16 mm/s.2. In order to explore the dissimilar steel welding, the flow behavior of the molten pool surface. Based on the same test platform and test method, studied 304 / Q235 carbon steel, 316 L stainless steel/Q235 carbon steel, 304 stainless steel /316 L stainless steel three different kinds of dissimilar steel welding molten pool flow, in order to further explore the internal flow of dissimilar steel welding molten pool, element distribution of the weld area are studied by EDS method, the flow of the molten pool internal behavior by reasoning. Results show that when the stainless steel and carbon steel welding, metal molten pool surface made of stainless steel to carbon steel on one side of the flow, when the 304 stainless steel and 316 L stainless steel welding off to 304 stainless steel side, of which 304 stainless steel/Q235 carbon steel weld pool surface of the liquid metal flow velocity is about 24 to 28 mm/s, 316 L stainless steel/Q235 carbon steel weld pool surface of the liquid metal flow speed of about 20 to 24 mm/s; 304 stainless steel / 316 Lstainless steel weld pool surface of the liquid metal flow velocity is about 15 to 18 mm/s, internal liquid metal molten pool is made by carbon steel side to side of stainless steel.3. For accuracy of molten pool image data post-processing, on 304 stainless steel TIG weld pool image preprocessing, binarization, based on the Canny, Prewitt, Robert, Sobel, Laplace five kinds of edge detection operator to extract the edge, to explore the best data post-processing method, the results show that: at first, the image preprocessing, image after binarization, then use Robert edge detection operator to extract the optimal pool edge.