An upper member of a steel piston has a chemical composition which consists of, in mass %, C: 0.15 to 0.30%, Si: 0.02 to 1.00%, Mn: 0.20 to 0.80%, P: 0.020% or less, S: 0.028% or less, Cr: 0.80 to 1.50%, Mo: 0.08 to 0.40%, V: 0.10 to 0.40%, Al: 0.005 to 0.060%, N: 0.0150% or less, O: 0.0030% or less, and the balance: Fe and impurities, and satisfies Formula (1) and Formula (2), in which, at a cross section parallel to the axial direction of the upper member, the number of Mn sulfides is 100.0 per mm.sup.2 or less, the number of coarse Mn sulfides having an equivalent circular diameter of 3.0 μm or more is within a range of 1.0 to 10.0 per mm.sup.2, and the number of oxides is 15.0 per mm.sup.2 or less.
0.42≤Mo+3V≤1.50  (1)
V/Mo≥0.50  (2)

A mould for hot forging includes a first half-mould and a second half-mould. The first and second half-moulds each include a mould holder having a recess and a die provided with an impression. The die is combined with the mould holder at the recess. At least one of the first half-mould and the second half-mould is provided with at least one feeding channel for a lubricating-cooling liquid, extending from an outer wall of the mould holder to the recess of the mould holder, and with a plurality of distribution channels for the lubricating-cooling liquid. At least one quota of the plurality of distribution channels includes distribution channels extending from a wall of the die facing the recess, to the impression. The at least one feeding channel and the distribution channels face at least one gap formed between the mould holder and the respective die at the recess.

A mould for hot forging includes a first half-mould and a second half-mould. The first and second half-moulds each include a mould holder having a recess and a die provided with an impression. The die is combined with the mould holder at the recess. At least one of the first half-mould and the second half-mould is provided with at least one feeding channel for a lubricating-cooling liquid, extending from an outer wall of the mould holder to the recess of the mould holder, and with a plurality of distribution channels for the lubricating-cooling liquid. At least one quota of the plurality of distribution channels includes distribution channels extending from a wall of the die facing the recess, to the impression. The at least one feeding channel and the distribution channels face at least one gap formed between the mould holder and the respective die at the recess.

A method for manufacturing a blade, the method includes casting a nickel alloy blade precursor having an airfoil and a root. The airfoil and the root are solution heat treating differently from each other. After the solution heat treating, the root is wrought processed. After the wrought processing, an exterior of the root is machined.

The disclosure discloses a method of producing a magnesium alloy wheel hub, comprises the following steps: step 1, heating a magnesium alloy bar to 350-430° C. and keeping the temperature for 20 minutes; step 2, initially forging and forming the bar under a forging press, the forging speed is 6-15 mm/s; step 3, finally forging and forming the bar under a forging press, and the forging speed is 5-8 mm/s; step 4, testing the microstructure and material properties of the final forged blank to obtain the layered material property distribution on the thickness of the blank; step 5, according to the layered material property distribution on the thickness of the blank obtained in step 4, selecting the part that meets the requirements to make a magnesium alloy wheel hub. According to the different properties in the thickness direction of the blank, the spoke orientation of the magnesium alloy wheel can be quickly designed according to the needs, and the magnesium alloy wheel that meets the usage performance can be obtained, which greatly improves the design and processing efficiency.

The disclosure discloses a method of producing a magnesium alloy wheel hub, comprises the following steps: step 1, heating a magnesium alloy bar to 350-430° C. and keeping the temperature for 20 minutes; step 2, initially forging and forming the bar under a forging press, the forging speed is 6-15 mm/s; step 3, finally forging and forming the bar under a forging press, and the forging speed is 5-8 mm/s; step 4, testing the microstructure and material properties of the final forged blank to obtain the layered material property distribution on the thickness of the blank; step 5, according to the layered material property distribution on the thickness of the blank obtained in step 4, selecting the part that meets the requirements to make a magnesium alloy wheel hub. According to the different properties in the thickness direction of the blank, the spoke orientation of the magnesium alloy wheel can be quickly designed according to the needs, and the magnesium alloy wheel that meets the usage performance can be obtained, which greatly improves the design and processing efficiency.

A forging and pressing production systems enables at least one material to be formed by hot melt and forging and pressing by itself without human operation, thereby completing the mass production of the material. Operating factors such as the pressure, temperature and mold required for formation are taken into account, and the identification requirements for the material are reduced, thereby realizing large-scale production.

A forging and pressing production systems enables at least one material to be formed by hot melt and forging and pressing by itself without human operation, thereby completing the mass production of the material. Operating factors such as the pressure, temperature and mold required for formation are taken into account, and the identification requirements for the material are reduced, thereby realizing large-scale production.

A method of manufacturing a forged product includes a heating step, a first and a second forging steps, wherein the forging temperature in the heating step is 450° C. or higher and 550° C. or lower, and surface temperatures of the upper molding part of the first upper die in the first forging step and the upper molding part of the second upper die in the second forging step are 150° C. or higher and 190° C. or lower, surface temperatures of the lower molding parts of the first and the second lower dies are 190° C. or higher and 230° C. or lower, and the surface temperatures of the lower molding parts of the first and the second lower dies are higher by 5° C. or more than the surface temperatures of the upper molding parts of the first and the second upper dies.

Method for producing a steel part comprising providing a semi-finished product made of a steel comprising, by weight: 0.35%≤C≤0.60%; 0.15%≤Si≤0.5%; 0.8%≤Mn≤2.0%; 0.0003%≤B≤0.01%; 0.003%≤Mo≤1.0%; 1.0%≤Cr≤2.0%; 0.01%≤Ti≤0.04%; 0.003%≤N≤0.01%; S≤0.015%; P≤0.015%; 0.01%≤Ni≤1.0%; 0.01%≤Nb≤0.1%; optionally 0≤Al≤0.1%; 0≤V≤0.5%; and the remainder consisting of iron and unavoidable impurities. The method further including annealing this semi-finished product at a temperature strictly lower than the Ac1 temperature of the steel; cold forming the semi-finished product into a cold formed product; subjecting the cold formed product to a heat treatment comprising heating the cold formed product to a temperature greater than or equal to the Ac3 temperature of the steel; and holding the product at a holding temperature comprised between 300° C. and 400° C. for a time comprised between 15 minutes and 2 hours.