Research On Defect Quantitative Analyses And Effects Of Building Steel Structure Welding

The research focuses on the defect equivalent analytical methods in building steel structure butt weld fusion and the effects of non-crack-type defects on the normal use of butt weld fusion.The sizes of defects in building steel structure weld are analyzed quantitatively by ultrasonic testing.With the frequency,transmitter and sound field of ultrasonic transverse wave considered,the thickness of welding specimen is checked to determine K.Through theoretical analysis and experimental testing the reflector contrast is determined:similar to transverse hole defects using the long cross-holeφ3 in RB, CSK-IC test block and the short cross-holeφ1 in CSK-Ⅲtest block.The formula calculating the equivalent diameter of long cross-hole and short cross-hole is deduced. In terms of the erect bore defects(near the roots of similar points) in building steel structure welding,we produce special reflectors and draw dB-φcurves and regression function,using insert method to calculate the equivalent diameter and validating the method to be correct.The research focuses on two types of non-crack-type defects in building steel structure butt weld fusion:defects due to artificial drilling(simulated smooth hole wall defects) and defects emerging in the welding process(rough hole wall).The equivalent sizes of the two types of defects,calculated by the ultrasonic flaw detection and analysis, are simplified as the largest cross-section parallel to the welding area.The defect rates of a variety of non-crack-type defects are expressed by the percentage the defects account for in the total cross-sectional welding area.The results show the different effects of the non-crack-type defect size,the shape of the hole wall,the location and combination of location place on the weld individual carrying capacity.In theory,we analyze the defects that affect the weld individual carrying capacity based on their combination of location place and the root crack tip shape.The research compared the experimental tensile test results with the project Grid bar:the experimental results are in accordance with the project Grid bar test results.Based on the experimental results,the non-crack-type defect rate limits of ultrasonic flaw detection under different conditions of carrying capacity in building steel structure butt weld fusion are drawn or cut.