Effect of Cold Working on the Mechanical Properties of Rapidly Solidified Fe-30Cr-5Al Alloy Powder Consolidated by Sheath Rolling

Rapidly solidified Fe-30Cr-5Al alloy powders produced by the rotating-water-atomization-process were sheath-rolled. Three kinds of sheath-rolling which are hot sheath-rolling, cold sheath-rolling after hot sheath-rolling and sintering after cold sheath-rolling were carried out. Microstructures and mechanical properties of the sheath-rolled samples were examined. Sintering after cold sheath-rolling was not effective in the breakage of Al2O3 oxide films of the powder particle surface. By hot sheath-rolling, Al2O3 oxide films were broken or divided to small pieces and the shape of Al2O3 was changed from plate to granular form. By hot sheath-rolling, the mean diameter of Al2O3 was 2.5 μm for the reduction in cross-sectional area of 80%. Cold sheath-rolling after hot sheath-rolling were very effective in fine dispersion of Al2O3 oxides. By cold sheath-rolling after hot sheath-rolling, the mean diameter of Al2O3 was 1.2 μm and the tensile strength was 1060 MPa for the reduction in cross-sectional area of 79%. The tensile strength and elongation increased drastically with decreasing mean diameter of Al2O3 oxides to less than 2 μm.