EFFECT OF SUPERHEAT ON THE SOLIDIFICATION STRUCTURES OF AISI 310S AUSTENITIC STAINLESS-STEEL

An experimental study was carried out to investigate the evolution of macrostructure and microstructure in AISI 310S stainless steel during solidification. Experimental findings suggested that the macrostructur e and the microstructure of the cast material responded differently to variations in casting temperature. As the casting temperature decreas ed, the macrostructure was refined, as expected, but the microstructur e coarsened. A relationship was established between the proportion of equiaxed zone and superheat as follows: pet equiaxed zone = a + b In ( 1/Delta T) where a and b are constants. The relationship between grain width and superheat could be expressed by the equation gw = e(c+d/Del ta/T) where c and d are constants determined by the distance from the edge of the ingot. The relationship between primary arm spacing and su perheat could be expressed by the equation lambda(1) = p+q 1n (1/Delta T) where p and q are constants determined by the distance from the ed ge of the ingot. The parameter ''grain width ratio'' has been introduc ed to describe the relationship between the shape and the nucleation a nd growth kinetics of the columnar grains.