tailieunhanh - Arc Welding 2011 Part 13

Tham khảo tài liệu 'arc welding 2011 part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The Mechanism of Undercut Formation and High Speed Welding Technology 231 Fig. 12. Calculated result of temperature of welding pool surface as cooling 190A . In figure 13 we can also see with the time of heating extended the fusion line near the temperature gradient decreased. It can be concluded small standard slow welding can reduce the fusion line near the temperature gradient. Designated welding experimental results Experiment conditions and welding standard Experiment mainly carried out from three aspects one basic situation of contrast is the different welding current different welding time but heat input is the same the second Fig. 13. Relationship between temperature gradient and arc time. b current is 150A 232 Arc Welding situation it is the same but the welding arc burning time different changed the third is under the same welding standard but welding materials is not the same as the sulphur content is different. The specimens uses the Q235 steel plate. The actual weldedtestspecimen respectively in two kinds with sulphur content in the and . Table 1 is designated welding experimental parameters. The welding conditions TIG welding dc electric reverse connect Ar gas protection gas flow 101 min tungsten extreme view of 60 6 mm distance to the workpiece. The numbers in table 2 is the value of the welding current multiplied the welding time because of the actual welding arc current difference can cause energy loss different and it can not stand of the truely welding heat input but its can indirectly reflect the quantity of welding heat input. In the experiment strictly control arc burning time and using thermovision and infrared thermometer measuring the temperature distribution of welding pool and some point of the heat cycle especially near the fusion line of thermal cycle. After the specimen cooled with precision surface measuring instrument measuring the surface shape of the solder joint we can get bite edge data. The experiments .