In Search of the Prediction of Hot Cracking in Aluminium Alloys

Abstract

Hot tearing remains a major problem of casting technology despite decades-long efforts to develop a working hot tearing criterion and to implement it into casting process computer simulation. Existing models allow one to calculate the stress–strain situation in a casting (ingot, billet) and to compare it with the chosen hot tearing criterion. Two kinds of hot tearing criteria are available in literature: mechanical and non-mechanical one. The mechanical criteria of hot tearing are derived based on mechanical behaviour semi-solid, and the non-mechanical one is based on other properties of semi-solid. In most successful cases, the simulation shows a relative probability of hot tearing and the sensitivity of this probability to such process parameters as casting speed, casting dimensions, and casting practice. None of the existing criteria, however, can give the quantitative answer on whether the hot crack will appear or not and what will be the extent of hot cracking (position, length, shape). This chapter outlines the requirements for a modern hot tearing criterion as well as the future development of hot tearing research in terms of mechanisms of hot crack nucleation and propagation.