Abstract: Method of producing cast-steel molded parts especially suited to low-temperature applications, particularly, handling liquid hydrogen. Conventional high-nickel alloy austenitic stainless steels must be used as forged, not cast, products with high wall thicknesses to lend them the mechanical properties sufficient for handling liquid hydrogen and preventing hydrogen embrittlement. According to the method, an alloy consisting essentially of 2.5-4.5% Si, 10.5-19.0% Cr, 13.5-20.0% Ni, 0.5-1.5% Mn, 1.0-2.0% Co, and 0.5-1.5% Mo is melted; the melt is poured into a mold; and the molded part is solution heat-treated at a temperature of from 950° C. to 1150° C. The cast steel parts have a high content of hydrogen-embrittlement curtailing silicon, and nickel, chromium and other components lending them properties not essentially due to the conventional-steel presence of carbon. The molded parts thus produced have sufficient fracture toughness even at liquid-hydrogen temperatures.

Abstract: A selective laser sintering method alternately repeats a step of forming silicon alloy A2 powder (metal powder) in layers, the silicon alloy A2 powder made of high silicon stainless steel containing C:less than 0.10, Si:2.0˜9.0, Mn:0.05˜6.0, Cu:0.5˜4.0, Ni:1.0˜24.0, Cr:6.0˜28.0, Mo:0.2˜4.0, Nb:0.03˜2.0 in wt % and the balance of Fe and inevitable impurities, and a step of selectively applying a laser to the silicon alloy A2 powder formed in layers to melt and sinter the silicon alloy A2 powder.