Optimization of Tensile Strength of Butt Joint Weldment on Mild Steel Plate Using Response Surface Methodology

Abstract

The service life of engineering structures is affected by the quality
and strength of the welded joints. Tensile tests are performed for
several reasons. The results obtained are used in selecting materials
for engineering applications. Tensile properties frequently are
included in material specifications to ensure quality. This tests often
are measured during development of new materials and processes, so
that different materials and processes can be compared. Tensile tests
often are used to predict the behavior of a material/ weldment under
forms of loading other than uniaxial tension. This study was carried
out with the aim of improving the tensile properties of a mild steel
weldment from thermal effect of the welding process. Mild steel plate
was cut into dimension 60mmx40mmx10mm with a power hacksaw,
grinded and cleaned before the welding process. The experimental
matrix was made of twenty (20) runs, generated by the design expert
11.1.0.1 software adopting the central composite design. The
response was measured, which is the tensile strength and then
modelled using the response surface methodology. In this study the
response surface methodology was applied to optimize and predict
the maximum tensile strength of a butt joint weldment on an I-section
mild steel plate. The result obtained in this study shows that the
current and voltage has a very strong influence on the tensile
strength. Based on the findings, it is summarized that the Maximum
tensile strength is 526.316MPa when a welding voltage of 24V,
current of 170A and gas flow rate of 13lit/min.