Effect of Electric Power Arc Inputs on the Microstructure and Fracture Surface of 0.4%C Steel
Authors: Obidimma DI, Awheme O
The result of an investigation on the effect of electric power arc inputs on the microstructure and fracture surface of 0.4%C steel was analyzed in this study. The power inputs were controlled by varied welding current, at constant arc voltage of 40 V, welding speed of 3.2 mm/sec and electrode gauge of 3.2 mm. The currents were varied at 100 A for low heat input, 112.5 A for medium heat input and 125 A for high heat input. Microstructural and fracture analyses were carried out on the specimens to determine their microstructural configurations. The results showed that increasing the welding current from 100 A-125 A caused a corresponding increase in microstructural grains of the specimens. At 100 A, the time for solidification was less and resulted in smaller fine grains. At 125 A, the time required for solidification increases and yielded coarse grains. The fracture surfaces showed dimples of varying sizes and shapes indicating ductile to brittle transition kind of failure. Low heat, shows a classic mechanism of ductile fracture known as microvoid coalescence. Medium heat shows microvoids coalescence with some tear ridges and river pattern markings which points to the origin of failure. High heat shows trans-granular form of fracture which indicates brittle fracture in which the failure occurred with lower plastic deformation.
Affiliations: Department of Mechanical Engineering, Faculty of Engineering, University of Benin, Benin City, Nigeria.
Keywords: Microstructure, Welding, Temperature, Weld Metal, Heat Affected Zone, Fusion Zone
Published date: 2019/12/30