Hitachi Metals, Ltd.

Junji Hayakawa

Masahide Kawabata

Hirofumi Kimura

Susumu Katsuragi

Tomonori Namito

Hideo Kuribayashi

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&#x2212;Nb+0.05Cr+0.65Ni&#x2212;5, and the formula (2) of B=7.8Nb.

Heat-resistant, austenitic cast steel having excellent thermal fatigue properties, and exhaust member made thereof

A heat-resistant, ferritic cast steel having excellent melt flowability, gas defect resistance, toughness and machinability, which has a composition comprising by mass, C: 0.32-0.45%, Si: 0.85% or less, Mn: 0.15-2%, Ni: 1.5% or less, Cr: 16-23%, Nb: 3.2-4.5%, Nb/C: 9-11.5, N: 0.15% or less, S: (Nb/20&#x2212;0.1) to 0.2%, W and/or Mo: 3.2% or less in total (W+Mo), the balance being Fe and inevitable impurities, and a structure in which the area ratio of a eutectic (&#x3b4;+NbC) phase of &#x3b4; ferrite and Nb carbide (NbC) is 60-80%, and the area ratio of manganese chromium sulfide (MnCr)S is 0.2-1.2%, and an exhaust member made thereof.

Heat-resistant, ferritic cast steel having excellent melt flowability, gas defect resistance, toughness and machinability, and exhaust member made thereof

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Miyako-gun, Japan

Junji Hayakawa