Effects of Joint Preparation Angle of Single-Vee Butt Welds on the Tensile Strength of ASTM A36 Carbon Steel

Welding is a multi-faceted procedure of manufacturing and can occur at any point during the creation of a product. Quality issues in welding can have disastrous, or even deadly, consequences. The issue of weld preparation angle is one of several different elements that have a direct correlation on the quality of a welded joint. The purpose of this research centers on resultant tensile strength of a single-vee butt joint in carbon steel with various preparation angles. Preparation angles were machined on twenty-six pieces of ASTM A36 carbon steel in 5° increments in order to produce thirteen samples with included preparation angles ranging from 0° to 120°. Test samples were developed using an automated welding process that remained consistent for all of the welds. Each sample was plasma cut into ten coupons, which were machined to have a uniform cross section of the welded joint and surrounding parent material using a computer numerically controlled machining center. This yielded a total population of 130 coupons, which were tested to failure using a United Testing Systems stress/strain tensile tester. The empirical data were analyzed via the use of SPSS 18 statistical software. Initially, the level of population variance was assessed within groups and between groups by use of a one-way ANOVA test at the .05 alpha level. The result showed a statistically significant difference of the sample population. Secondly, a comparison of the data at various preparation angles to that of the industry standard angle of 60° was assessed using a Bonferroni multiple comparisons at the .05 alpha level, which resulted in one angle being statistically significant compared to the industry standard.© 2011 ASME