INFLUENCE OF WELD DEFECTS ON THE MECHANICAL PROPERTIES OF ALUMINUM ALLOY WELDMENTS (To Purchase Call 1-800-854-7179 USA/Canada or 303-397-7956 Worldwide)
A literature survey was conducted to determine the information available on the influence of defects in aluminum weldments on their tensile strength@ fatigue strength@ and notch toughness. Of the hundreds of papers examined@ only about 30 contained pertinent and quantitative data@ much of which concerned heat-treatable alloys for military or aerospace applications. Except for some British investigations@ little study has been reported for the more common structural alloys@ such as the 5000 and 6000 series. In broad terms@ Lhe transverse tensile strength of an aluminum butt joint is lowered in proportion to the fraction of cross section represented by the defects. Conflicting opinions have been expressed regarding the effect of porosity on static strength. While earlier reports were that considerable porosity could be tolerated without loss of strength@ several recent papers indicate significant reduction of tensile strength to be caused by small amounts of porosity. These papers suggest that spherical porosity is effective even at very fine diameters (<0.005 in.). Planar defects such as lack of fusion or penetration are directional in effect but also act by reducing the effective cross-sectional area. Weld reinforcement raises the tensile strength when the weld metal is of lower strength than the base plate.