Hitachi, Ltd.

Minoru Morikawa

Yutaka Fukui

Nobuyuki Iizuka

Shigeyoshi Nakamura

Junji Sakai

Tetsuo Kashimura

Soichi Kurosawa

Syogo Morimoto

Yoshitsugu Maehashi

A cobalt-base alloy comprises 0.2-1 wt % C 0.4-2 wt % Si, 0.2-1.5 wt % Mn, 5-15 wt % Ni, 20-35 wt % Cr, 3-15 wt % W, 0.003-0.1 wt % Ni, 20-35 wt % Cr, 3-15 wt % W, 0.003-0.1 wt % B, 0.05-1 wt % Nb, 0.01-1 wt % Ta, 2 wt % or less Fe, 30 ppm or less oxygen, 100 ppm or less nitrogen, and the balance of 45 wt % or more Co, wherein the content of Si is larger than that of Mn. The alloy is in a form of casting and has a structure containing a eutectic carbide and a secondary carbide dispersed therein. The cast alloy is produced through solution treatment at 1,100.degree.-1.200.degree. C., and aging treatment at 950.degree.-1,050.degree. C., and cooling rate after the solution treatment and after the aging treatment is 150.degree. to 300.degree. C./h. A gas turbine nozzle is made of a casting of the above-mentioned alloy.

Cobalt-base alloy having high strength and high toughness, production

A mold for casting particularly a core, is produced by mixing refractory particles with colloidal alumina to give a slurry, filling said slurry in a pattern having water absorption properties, solidifying the slurry, followed by drying and firing. The resulting mold, particularly core, has high dimensional accuracy with no cracks.

Process for producing core for casting

Growing community of inventors

Katsuta, Japan

Minoru Morikawa