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The IUP Journal of Science & Technology
Microstructure and Properties of Welded 15CDV6 Alloy Steel
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In this study of non-destructive testing, tensile test of weldments have been carried out on a 15CDV6 alloy steel using Gas Tungsten Arc Welding (GTAW) with non-pulsed and pulsed current at different frequencies—2, 4 and 6 Hz respectively. The radiography, liquid penetrant test and mechanical properties of the weldments have been evaluated and compared with non-pulsed and pulsed current welding at different frequencies. The radiography, liquid penetrant test and tensile test have been carried out on the weldments of the above material having two different thicknesses, i.e., 1.5 and 5.0 mm of 15CDV6 alloy steel. This study also presents the weld joint efficiency of the material at different welding process parameters. The aim of this study is to see the effect of pulsed current on the quality of weldments. The experimental results pertaining to different welding parameters for the above alloys using pulsed and non-pulsed current GTAW are discussed and compared.

 
 

Pulsed Current Welding (PCW) was introduced in the late 1960s as a variant of Constant Current Welding (CCW). PCW process has many specific advantages over CCW. These include enhanced arc stability, increased weld depth/width ratio, narrower Heat Affected Zone (HAZ) range, reduced hot crack sensitivity, refined grain size, reduced porosity, low heat input, low distortion, controlled weld bead volume, less absorption of gas by weld pool and better control of the Fusion Zone (FZ) [1-8]. Pulsed current welding technology has been widely used in fabrication of high pressure air bottles, rocket motors, and structures in aerospace applications, such as aircrafts, rockets and missiles. Switching between predetermined high and low levels of welding current can be used to produce pulsed current gas tungsten arc welds [9].

Very few reports have been published on pulsed current GTAW of alloy steels. Previous investigations have proved that, during pulsed current GTAW welding, a higher pulse frequency at smaller pulse spacing can enhance the energy density of the welding heat source, thereby reducing the angular distortion of stainless steel weldments [9]. So far, the studies reported were on the use of pulsed current welding to study the effect of pulsed current, shielding gas composition, weld speed and bead shape, on the incidence of welding defects and joint strength using alloy sheets of 5,083 type [8] , angular distortion in stainless steel weldments of 304 and 310 type [9], and on the microstructure [10] and weld bead geometry [11]. This prompted us to study the effect of pulsed current on welding characteristics of alloy steel, as used in aerospace applications. In the present work, 15CDV6 alloy steel weldments using pulsed and non-pulsed current GTAW have been examined and the macrostructure and microstructure development in Fusion Zone (FZ) and Heat Affected Zone (HAZ) of the weldments have been studied.

 
 

Science and Technology Journal, Welded 15CDV6 Alloy Steel, Gas Tungsten Arc Welding, GTAW, Pulsed Current Welding, Constant Current Welding, Microstructure Development, Macrostructure Development, Aerospace Applications, Non-Destructive Testing, Alloy Steel Weldments, Welding Engineering.