A low thermal expansion superalloy is composed of, in mass %, 0.1% or less of C, 0.1-1.0% of Si, 1.0% or less of Mn, 25-32% of Ni, more than 18% but less than 24% of Co, more than 0.25% but 1.0% or less of Al, 0.5-1.5% of Ti, more than 2.1% but less than 3.0% of Nb, 0.001-0.01% of B and 0.0005-0.01% of Mg, with the balance of Fe and unavoidable impurities, while satisfying Mg/S1, 52.91.235Ni+Co<55.8%, (Al+Ti+Nb) is 3.5-5.5%, and the F value is 8% or less. In the superalloy, a granular intermetallic compound containing Si, Nb, and Ni alone or in a total amount of 36 mass % or more is precipitated at a grain boundary of an austenite matrix, and an intermetallic compound including a larger concentration of Ni, Al, Ti, and Nb and having 50 nm or smaller of an average diameter is precipitated in the austenite matrix.

The invention relates to a mould for the manufacturing of mould steels in an inert gas or a pressurized electro slag re-melting apparatus. The mould comprises a non-rectangular and non-circular inner copper sleeve having a width, w, of 1000-2500 mm and a thickness, t, of 700-1250 mm, wherein the short sides in the thickness direction of the copper sleeve at least partly have sections with curved surfaces and wherein the long sides in the width direction at least partly have sections with curved surfaces.

The invention relates to a mould for the manufacturing of mould steels in an inert gas or a pressurized electro slag re-melting apparatus. The mould comprises a non-rectangular and non-circular inner copper sleeve having a width, w, of 1000-2500 mm and a thickness, t, of 700-1250 mm, wherein the short sides in the thickness direction of the copper sleeve at least partly have sections with curved surfaces and wherein the long sides in the width direction at least partly have sections with curved surfaces.

A method for manufacturing a forged steel roll comprises: casting, by the ESR method, a steel ingot which contains, by mass %, C: 0.3% or more, Si: 0.2% or more, Cr: 2.0-13.0% and Mo: 0.2% or more, and further contains Bi at 10-100 ppm by mass; and forging the steel ingot to manufacture the roll. According to this method, since freckle defects can be sealed near the center of the steel ingot, the roll can be stably used over a long period of time.

A method for manufacturing a forged steel roll comprises: casting, by the ESR method, a steel ingot which contains, by mass %, C: 0.3% or more, Si: 0.2% or more, Cr: 2.0-13.0% and Mo: 0.2% or more, and further contains Bi at 10-100 ppm by mass; and forging the steel ingot to manufacture the roll. According to this method, since freckle defects can be sealed near the center of the steel ingot, the roll can be stably used over a long period of time.

An electro-slag remelting installation includes a mold and a consumable electrode that extends into the mold. The consumable electrode has an axis that is oriented obliquely to a vertical axis.

An electro-slag remelting installation includes a mold and a consumable electrode that extends into the mold. The consumable electrode has an axis that is oriented obliquely to a vertical axis.

Method for manufacturing a nickel-based alloy product, including: a step of supplying an ingot of a nickel-based alloy including at least one intermetallic phase, a first forging step of forging the ingot, during which the true strain rate is less than 1 s.sup.?1, a second forging step of forging the ingot, during which the true strain rate is greater than 1 s.sup.?1, and a step of static recrystallisation, after the second forging step, during which the ingot is exposed to a temperature of between 1000 and 1055? C. for a duration of between 30 minutes and 10 hours.

Method for manufacturing a nickel-based alloy product, including: a step of supplying an ingot of a nickel-based alloy including at least one intermetallic phase, a first forging step of forging the ingot, during which the true strain rate is less than 1 s.sup.?1, a second forging step of forging the ingot, during which the true strain rate is greater than 1 s.sup.?1, and a step of static recrystallisation, after the second forging step, during which the ingot is exposed to a temperature of between 1000 and 1055? C. for a duration of between 30 minutes and 10 hours.

Disclosed is a steel composition including specified ranges of Ni; Mo; Co; Mo+Co+Si+Mn+Cu+W+V+Nb+Zr+Ta+Cr+C; Co+Mo; Ni+Co+Mo; and traces of Al; Ti; N; Si; Mn; C; S; P; B; H; O; Cr; Cu; W; Zr; Ca; Mg; Nb; V; and Ta in specified ranges; the remainder being iron and impurities. The inclusion population, as observed by image analysis over a polished surface measuring 650 mm.sup.2 if hot-formed or hot-rolled; and measuring 800 mm.sup.2 if cold-rolled, does not contain non-metallic inclusions of diameter >10 ?m, and, in the case of a hot-rolled sheet, does not contain more than four non-metallic inclusions of diameter 5-10 ?m over 100 mm.sup.2, the observation being performed by image analysis over a polished surface measuring 650 mm.sup.2.