Comparison on grindability and surface integrity in creep feed grinding of GH4169, K403, DZ408 and DD6 nickel-based superalloys

Abstract

Comparative study was conducted on the grindability of wrought GH4169, equiaxial cast K403, directionally solidified cast DZ408 and single crystal DD6 superalloys by using the brown alumina wheels during the creep feed grinding process with regard to the grinding force, grinding ratio, wheel wear and surface integrity. The grinding forces were found to increase in the following order: DD6, GH4169, K403 and DZ408; and DD6 alloy had the largest grinding ratio, followed by GH4169, K403 and DZ408. In addition, the workpiece material adhesion and grain wear flats were found to be the main pattern of wheel wear in the grinding of DZ408, K403 and GH4169 alloys, while it was the wheel clogging for DD6 alloy. Irrespective of the workpiece material, the microhardness alternation of subsurface induced by thermal effect dominated over the mechanical effect with the increasing material removal rate (up to 6 mm3/(mm s)) and the softened level was 10–16.5 % to a depth of around 40 μm in this study. The surface defects, the highly deformed subsurface and the generation of micro cracks within the workpiece were found to be the main types of damage induced by the grinding operation. These results can provide insights into the effect of workpiece material on the grindability of different nickel-based superalloys in the investigation.