Abstract: A heat-resistant, austenitic cast steel having excellent thermal fatigue properties, comprising by mass 0.3-0.6% of C, 0.5-3% of Si, 0.5-2% of Mn, 15-30% of Cr, 6-30% of Ni, 0.6-5% of Nb, 0.01-0.5% of N, and 0.01-0.5% of S, C/N being 4-7, and the balance being Fe and inevitable impurities; and a ratio A/B of a Cr-carbide-forming index A to a Nb-carbide-forming index B being 0.6-1.7, wherein A and B are expressed by the formula (1) of A=8.5C?Nb+0.05Cr+0.65Ni?5, and the formula (2) of B=7.8Nb.

Abstract: A heat-resistant, austenitic cast steel having excellent thermal fatigue properties, comprising by mass 0.3-0.6% of C, 0.5-3% of Si, 0.5-2% of Mn, 15-30% of Cr, 6-30% of Ni, 0.6-5% of Nb, 0.01-0.5% of N, and 0.01-0.5% of S, C/N being 4-7, and the balance being Fe and inevitable impurities; and a ratio A/B of a Cr-carbide-forming index A to a Nb-carbide-forming index B being 0.6-1.7, wherein A and B are expressed by the formula (1) of A=8.5C?Nb+0.05Cr+0.65Ni?5, and the formula (2) of B=7.8Nb.

Abstract: A heat-resistant, austenitic cast steel having excellent machinability comprising by mass 0.4-0.55% of C, 1-2% of Si, 0.5-1.5% of Mn, 18-27% of Cr, 8-22% of Ni, 1.5-2.5% of Nb, 0.01-0.3% of N, 0.1-0.2% of S, and 0.02-0.15% of Al, the balance being Fe and inevitable impurities, a machinability index I represented by the following formula: I=100×S+75×Al+0.75×Mn?10×C?2×Nb?0.25×Cr?0.15×Ni?1.2×N, wherein each element symbol represents % by mass of each element in the cast steel, meeting the condition of ?3.0?I?+14.0, and an exhaust member made thereof.

Abstract: A heat-resistant, cast ferritic steel having excellent machinability comprising by mass 0.32-0.48% of C, 0.85% or less of Si, 0.1-2% of Mn, 1.5% or less of Ni, 16-23% of Cr, 3.2-5% of Nb, Nb/C being 9-11.5, 0.15% or less of N, 0.05-0.2% of S, and 0.01-0.08% of Al, the balance being Fe and inevitable impurities, and an exhaust member made thereof.

Abstract: A heat-resistant, cast ferritic steel having excellent machinability comprising by mass 0.32-0.48% of C, 0.85% or less of Si, 0.1-2% of Mn, 1.5% or less of Ni, 16-23% of Cr, 3.2-5% of Nb, Nb/C being 9-11.5, 0.15% or less of N, 0.05-0.2% of S, and 0.01-0.08% of Al, the balance being Fe and inevitable impurities, and an exhaust member made thereof.

Abstract: A heat-resistant, austenitic cast steel having excellent machinability comprising by mass 0.4-0.55% of C, 1-2% of Si, 0.5-1.5% of Mn, 18-27% of Cr, 8-22% of Ni, 1.5-2.5% of Nb, 0.01-0.3% of N, 0.1-0.2% of S, and 0.02-0.15% of Al, the balance being Fe and inevitable impurities, a machinability index I represented by the following formula: I=100×S+75×Al+0.75×Mn?10×C?2×Nb?0.25×Cr?0.15×Ni?1.2×N, wherein each element symbol represents % by mass of each element in the cast steel, meeting the condition of ?3.0?I?+14.0, and an exhaust member made thereof.

Abstract: An integrally cast steel piston for internal engines, the cast steel having (a) a composition comprising 0.8% or less of C, 3% or less of Si, 3% or less of Mn,0.2% or less of S, 3% or less of Ni, 6% or less of Cr, 6% or less of Cu, and 0.01-3% of Nb, the balance being substantially Fe and inevitable impurities, or (b) a composition comprising 0.1-0.8% of C, 3% or less of Si, 3% or less of Mn, 0.2% or less of S, 10% or less of Ni, 30% or less of Cr, 6 % or less of Cu, and 0.05-8% of Nb, the balance being substantially Fe and inevitable impurities, by mass.

Abstract: An integrally cast steel piston for internal engines, the cast steel having (a) a composition comprising 0.8% or less of C, 3% or less of Si, 3% or less of Mn, 0.2% or less of S, 3% or less of Ni, 6% or less of Cr, 6% or less of Cu, and 0.01-3% of Nb, the balance being substantially Fe and inevitable impurities, or (b) a composition comprising 0.1-0.8% of C, 3% or less of Si, 3% or less of Mn, 0.2% or less of S, 10% or less of Ni, 30% or less of Cr, 6% or less of Cu, and 0.05-8% of Nb, the balance being substantially Fe and inevitable impurities, by mass.

Abstract: The present invention provides a cast steel for ring-shaped components that has a low average coefficient of thermal expansion in a temperature range of 20° C. to 500° C. and high strength and good oxidation resistance at 500° C., which are required for ring-shaped components for use as blade rings and seal ring retainers of gas turbines, and that can hence be used for blade rings and seal ring retainers of gas turbines. Specifically, the present invention provides a high-strength and low-thermal expansion cast steel comprising, on a mass percentage basis, 0.1 to 0.8% of C, 0.1 to 1.0% of Si, 0.1 to 1.0% of Mn, 0.01 to 0.1% of S, greater than 40% and up to 50% of Ni, not greater than 4% (inclusive of 0%) of Co, greater than 1.5% and up to 4% of Cr, 0.01 to 0.1% of Al, and 0.001 to 0.1% of Mg, the remainder being substantially Fe.

Abstract: The present invention provides a cast steel for ring-shaped components that has a low average coefficient of thermal expansion in a temperature range of 20° C. to 500° C. and high strength and good oxidation resistance at 500° C., which are required for ring-shaped components for use as blade rings and seal ring retainers of gas turbines, and that can hence be used for blade rings and seal ring retainers of gas turbines. Specifically, the present invention provides a high-strength and low-thermal expansion cast steel comprising, on a mass percentage basis, 0.1 to 0.8% of C, 0.1 to 1.0% of Si, 0.1 to 1.0% of Mn, 0.01 to 0.1% of S, greater than 40% and up to 50% of Ni, not greater than 4% (inclusive of 0%) of Co, greater than 1.5% and up to 4% of Cr, 0.01 to 0.1% of Al, and 0.001 to 0.1% of Mg, the remainder being substantially Fe.