Abstract
In the present work, the effect of welding current and electrode negative (EN) ratio on microstructure and mechanical properties of square groove butt joint produced by alternating current gas metal arc welding (AC-GMAW) process has been investigated. The experiments were conducted using different combination of welding current ranging from 150 A to 250 A with three distinct EN ratios i.e., 0%, 30% and 50% on 5 mm thick steel plates at a constant joint gap of 1 mm and welding speed of 10 mm/s. The effect of current and EN ratio on welding soundness was evaluated through optical microscopy, tensile tests and micro-hardness mapping. The results revealed that, at higher values of currents, an increase in EN ratio resulted an increase in penetration depth. It was found that at a current of 250 A and a 50% EN ratio, the deep penetration was obtained. Tensile test results showed that the tensile strength properties improved with increasing current. Furthermore, the micro-hardness distribution was not strikingly affected by changing the EN ratio.
Highlights
Gas metal arc welding (GMAW) is one of the most commonly used welding processes to join a wide range of materials
Three thermocouples were positioned on the top side of the plate at distances of 10 mm (T1), 15 mm (T2) and 20 mm (T3) from the weld centerline, whereas two thermocouples were placed at the bottom of the plate (T4), one at the corner of the plate, and the other 5 mm (T5) away from the weld centerline
For an electrode negative (EN) ratio of 0%, the filler wire acted as an anode and base metal (BM) acted as a cathode during the complete pulse duration
Summary
Gas metal arc welding (GMAW) is one of the most commonly used welding processes to join a wide range of materials. It is an important constituent for the fabrication of pressure vessels, power plants, ships structures, aero-engine components and steam pipes. In recent years, pulsed alternating current gas metal arc welding (AC-GMAW), an advanced variant of conventional GMAW, has emerged, a relatively new welding process owing to its distinct characteristics [1,2]. The pulsed AC-GMAW process contains two distinct portions of the pulse. The electrode positive (EP) portion of the pulse provides better arc stability similar to conventional
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