Abstract: A cycle is repeated a plurality of times, which includes a forging process for placing a material to be forged in a lower die and pressing the material to be forged in this state and then separating an upper die from the material to be forged; an elevation process for lifting the material to be forged by using an elevation device to separate the material to be forged from the lower die; a rotation process for rotating the material to be forged around its center by using a rotation device; and a lowering process for placing the material to be forged rotated by the elevation device in the lower die.

Abstract: The present invention is to provide a method for manufacturing a martensite-based precipitation strengthening stainless steel, which effectively enables crystal grains to become finer by improving a solution treatment method. The method for manufacturing a martensite-based precipitation strengthening stainless steel containing 0.01 to 0.05 mass % of C, 0.2 mass % or less of Si, 0.4 mass % or less of Mn, 7.5 to 11.0 mass % of Ni, 10.5 to 14.5 mass % of Cr, 1.75 to 2.50 mass % of Mo, 0.9 to 2.0 mass % of Al, less than 0.2 mass % of Ti, and Fe and impurities as a remainder, which is provided by the present invention, includes performing a solid solution treatment at 845 to 895° C. once or more.

Abstract: There is provided a method for producing a Ni-based heat-resistant superalloy a primary ?? phase with an average particle size of at least 500 nm comprising the steps of: providing a material to be hot-worked having a composition consisting of, by mass, 0.001 to 0.05% C, 1.0 to 4.0% Al, 4.5 to 7.0% Ti, 12 to 18% Cr, 14 to 27% Co, 1.5 to 4.5% Mo, 0.5 to 2.5% W, 0.001 to 0.05% B, 0.001 to 0.1% Zr, and the balance of Ni with inevitable impurities; heating the material to be hot-worked in a temperature having a range of 1,130 to 1,200° C. for at least 2 hours; cooling the material to be hot-worked heated by the heating step to a hot working temperature or less at a cooling rate of at most 0.03° C./second; and subjecting the material to be hot-worked to hot working after the cooling step.

Abstract: There are provided a precipitation strengthening type martensitic steel having both a tensile strength of a 1500 MPa class and a high Charpy absorption energy of 30 J or higher, and a manufacturing process thereof. The precipitation strengthening type martensitic steel includes, in terms of mass %, 0.05% or less of C, 0.2% or less of Si, 0.4% or less of Mn, 7.5 to 11.0% of Ni, 10.5 to 13.5% of Cr, 1.75 to 2.5% of Mo, 0.9 to 2.0% of Al, less than 0.1% of Ti, and a remainder of Fe and impurities, and contains 0.1 to 6.0% of austenite in terms of a volume fraction.

Abstract: The present invention is to provide a method for manufacturing a martensite-based precipitation strengthening stainless steel, which effectively enables crystal grains to become finer by improving a solution treatment method. The method for manufacturing a martensite-based precipitation strengthening stainless steel containing 0.01 to 0.05 mass % of C, 0.2 mass % or less of Si, 0.4 mass % or less of Mn, 7.5 to 11.0 mass % of Ni, 10.5 to 14.5 mass % of Cr, 1.75 to 2.50 mass % of Mo, 0.9 to 2.0 mass % of Al, less than 0.2 mass % of Ti, and Fe and impurities as a remainder, which is provided by the present invention, includes performing a solid solution treatment at 845 to 895° C. once or more.

Abstract: A cycle is repeated a plurality of times, which includes a forging process for placing a material to be forged in a lower die and pressing the material to be forged in this state and then separating an upper die from the material to be forged; an elevation process for lifting the material to be forged by using an elevation device to separate the material to be forged from the lower die; a rotation process for rotating the material to be forged around its center by using a rotation device; and a lowering process for placing the material to be forged rotated by the elevation device in the lower die.

Abstract: There is provided a method for producing a Ni-based heat-resistant superalloy a primary ?? phase with an average particle size of at least 500 nm comprising the steps of: providing a material to be hot-worked having a composition consisting of, by mass, 0.001 to 0.05% C, 1.0 to 4.0% Al, 4.5 to 7.0% Ti, 12 to 18% Cr, 14 to 27% Co, 1.5 to 4.5% Mo, 0.5 to 2.5% W, 0.001 to 0.05% B, 0.001 to 0.1% Zr, and the balance of Ni with inevitable impurities; heating the material to be hot-worked in a temperature having a range of 1,130 to 1,200° C. for at least 2 hours; cooling the material to be hot-worked heated by the heating step to a hot working temperature or less at a cooling rate of at most 0.03° C./second; and subjecting the material to be hot-worked to hot working after the cooling step.

Abstract: There are provided a precipitation strengthening type martensitic steel having both a tensile strength of a 1500 MPa class and a high Charpy absorption energy of 30 J or higher, and a manufacturing process thereof. The precipitation strengthening type martensitic steel includes, in terms of mass %, 0.05% or less of C, 0.2% or less of Si, 0.4% or less of Mn, 7.5 to 11.0% of Ni, 10.5 to 13.5% of Cr, 1.75 to 2.5% of Mo, 0.9 to 2.0% of Al, less than 0.1% of Ti, and a remainder of Fe and impurities, and contains 0.1 to 6.0% of austenite in terms of a volume fraction.