Design of Experiment of High Pressure Steel Tank Using Tandem Submerged Arc Welding

The objective of this research is to investigate the appropriated Tandem Submerged Arc Welding (TSAW) by Punch through technique for high pressure steel tank in ship building industry. Electrode Type AWS A5.17 EM12K and powder flux type AWS A5.17 F7A6 have been applied with electric current at AC+ 550-700 Amp/DC 460-610 Amp. The welding travel speed is controlled between 515-590 mm/min with arc length between 25-30 mm which SM400 steel type is 25 mm thickness. The welding is in horizontal position without any bevel on the steel piece. Studying the suitable parameters from the experiment type 24 of this procedure experiment, the result has been found that the most suitable parameter set up for this welding is DC460, AC550, ST515, AL25. The experiment follows AWS D1.1 standard with 100% full penetration, tensile value at 542.61 N/mm2. Welding line supports impact test at 0°C with average value of 66 Joules, average hardness value at 156.4 HV, bending at 180°. With out any defected found. Moreover, this method can be reduced welding cost around18,482 baht/day and also increased the welding lenght around 168%.

Influence of Welding Parameters on Weld Appearance and Mechanical Properties in Twin-Wire Tandem Submerged Arc Welding of HSLA Steel

Effects of welding parameters on the weld bead appearance and mechanical properties in twin-wire tandem submerged arc welding of a high-strength low-alloy steel were investigated. Steel plates were welded using different combinations of welding current, voltage, inter-wire spacing and welding speed. The weld joints were characterized in detail by metallography. Hardness and tensile properties of the specimens were measured. The experimental analysis reveals that good weld appearance can be obtained for a range of inter-wire spacing from 55mm to 80mm. Leading wire current, trailing wire voltage and welding speed are the major factors affecting weld bead profile and microstructures in weld metal and fusion zone. Greater welding speed tends to produce higher cooling rate and favors the formation of strengthening phases like acicular ferrite and bainitic structures resulting in better mechanical properties.