Effects of Small Amounts of Additional Elements on Hot-cracking of Aluminum Alloys

Abstract

A study was made of the effects of small amounts of additional elements on hot-cracking of pure Al and alloys of Al-Mn, Al-Mg, Al-Mg-Si, Al-Cu-Mg and Al-Zn-Mg systems.Susceptibilities to cracking were evaluated for tests of fish-bone cracking, bead-on-plate weld cracking and ring cast cracking.The results obtained were as follows.(1) The susceptibility to cracking of aluminum alloys in ring cast cracking test decreased by the addition of Ti, B or Zr; in particular, by Ti.(2) However, the addition of Zr had the most remarkable effects on the decrease of susceptibility in weld cracking test. The addition of either Ti or B had no appreciable effects, though they had more grain refining power for weld metals than Zr.(3) None of other additional elements such as Be, V, and Mo were found to be effective for the decrease of hot-cracking of aluminum alloys, except for Al-Cu-Mg system.(4) The susceptibility to cracking of aluminum alloys in weld cracking test depended upon various metallurgical factors as well as upon grain size, while in ring-cast cracking it mainly depended upon grain size