A steel sheet with a tensile strength (TS) of 780 MPa or more and less than 1180 MPa, a member, and a method for producing them. In a region of the steel sheet within 4.9 μm in the thickness direction, a region with a Si concentration not more than one-third of the Si concentration in the chemical composition of the steel sheet and with a Mn concentration not more than one-third of the Mn concentration in the chemical composition of the steel sheet has a thickness of 1.0 μm or more. The lowest Si concentration L.sub.Si and the lowest Mn concentration L.sub.Mn in the region within 4.9 μm from the surface of the steel sheet and a Si concentration T.sub.Si and a Mn concentration T.sub.Mn at a quarter thickness position of the steel sheet satisfy the following formula (1):

L.sub.Si+L.sub.Mn≤(T.sub.Si+T.sub.Mn)/4  (1).

A steel sheet with a tensile strength (TS) of 1180 MPa or more, a member, and a method for producing them. In a region of the steel sheet within 4.9 μm in the thickness direction, a region with a Si concentration not more than one-third of the Si concentration in the chemical composition of the steel sheet and with a Mn concentration not more than one-third of the Mn concentration in the chemical composition of the steel sheet has a thickness of 1.0 μm or more. The lowest Si concentration L.sub.Si and the lowest Mn concentration L.sub.Mn in the region within 4.9 μm in the thickness direction from the surface of the steel sheet and a Si concentration T.sub.Si and a Mn concentration T.sub.Mn at a quarter thickness position of the steel sheet satisfy the following formula (1):

L.sub.Si+L.sub.Mn≤(T.sub.Si+T.sub.Mn)/4  (1).

An apparatus for laser materials processing including a laser (4) for generating a laser beam and a laser head (5) which is movable along at least one spatial direction and is connected to the laser via a light guide, and which emits a laser beam (7) capable of processing a material. The present invention also relates to an apparatus for selective laser melting or selective laser sintering having an apparatus for laser materials processing.

Disclosed herein are embodiments of hardfacing/hardbanding materials, alloys, or powder compositions that can have low chromium content or be chromium free. In some embodiments, the alloys can contain transition metal borides and borocarbides with a particular metallic component weight percentage. The disclosed alloys can have high hardness and ASTM G65 performance, making them advantageous for hardfacing/hardbanding applications.

A sprocket wheel, which is a machine component configured to slide relative to a bushing while being in contact with the bushing in an outer peripheral surface, includes a base made of a first metal, and an overlay that covers the base so as to constitute the outer peripheral surface. The surface of the overlay constituting the outer peripheral surface has been smoothed. Such a smoothed surface of the overlay makes the sprocket wheel less damaging to the bushing.

A martensitic steel including the following elements, expressed in percentage by weight 0.1%≤C≤0.4%; 0.2%≤Mn≤2%; 0.4%≤Si≤2%; 0.2%≤Cr≤1%; 0.01%≤Al≤1%; 0%≤S≤0.09%; 0%≤P≤0.09%; 0%≤N≤0.09%; and can contain one or more of the following optional elements 0%≤Ni≤1%; 0%≤Cu≤1%; 0%≤Mo≤0.1%; 0%≤Nb≤0.1%; 0%≤Ti≤0.1%; 0%≤V≤0.1%; 0.0015%≤B≤0.005%; 0%≤Sn≤0.1%; 0%≤Pb≤0.1%; 0%≤Sb≤0.1%; 0%≤Ca≤0.1%; the remainder composition being composed of iron and unavoidable impurities caused by processing, the microstructure of said steel having microstructure by area percentage including cumulative presence of residual austenite and bainite between 0% and 25%, the remaining microstructure being martensite at least 70%, and with an optional presence of ferrite between 0% and 10%.

A composite armor plate is disclosed. The composite armor plate includes a first layer made from an ultra-high hardness, high strength alloy that is bonded to a second layer made from a high fracture toughness alloy that also may have high strength. The composite armor plate according to the present provides a gradient of strength, hardness, and toughness. The composite armor plate according to the invention may also include third and fourth layers of different alloys that provide combinations of hardness, strength, and fracture toughness that are intermediate of the hardness, strength, and fracture toughness provided by the first and second steel layers. A method of making the composite armor plate is also disclosed.

To solve the problem about the difference in temperature increasing rate between an overlapped part and a one-sheet part so as to further improve the corrosion resistance of plating after hot stamping. An overlapped blank for hot stamping includes: a first steel sheet; and at least one second steel sheet connected to a surface of the first steel sheet via a welding point and smaller in area than the first steel sheet, wherein: the first steel sheet is a plated steel sheet having an aluminum-based plated layer on both faces of the first steel sheet, and the second steel sheet is a plated steel sheet having an aluminum-based plated layer on both faces of the second steel sheet; a coating weight of the aluminum-based plated layer on the first steel sheet is W1 (g/m.sup.2) in terms of an average coating weight on both the faces; a coating weight of the aluminum-based plated layer on a surface on a side not in contact with the first steel sheet in the second steel sheet is W2 (g/m.sup.2); and each of the W1 and the W2 is within a range of 20 g/m.sup.2 or more and 120 g/m.sup.2 or less, and satisfies relationships of Expression (1) and Expression (2).

The present disclosure discloses a hot-forging die with the conformal meshy structured cavity surface layer and a preparation method thereof. A large-scale hot-forging die includes a die substrate, and a sandwiched layer, a transition layer and a reinforcement layer are formed on the die substrate in sequence. The reinforcement layer and the transition layer are separated into a plurality of small units by the grooves. All the grooves are interconnected and communicated to form a meshy structure. The transition layer grooves are filled with ordinary soft material; the reinforcement layer grooves are filled with high temperature resistant soft material. The reinforcement layer material and the high temperature resistant soft material of the present disclosure cooperate with each other to obtain a cavity surface layer with properties of both hard and soft, strong and tough, which can fully release the large tensile stress that may occur on the surface of the die cavity during the welding process and under the service conditions of the die, so as to avoid hot cracks during welding process and service process.

The present disclosure discloses a hot-forging die with the conformal meshy structured cavity surface layer and a preparation method thereof. A large-scale hot-forging die includes a die substrate, and a sandwiched layer, a transition layer and a reinforcement layer are formed on the die substrate in sequence. The reinforcement layer and the transition layer are separated into a plurality of small units by the grooves. All the grooves are interconnected and communicated to form a meshy structure. The transition layer grooves are filled with ordinary soft material; the reinforcement layer grooves are filled with high temperature resistant soft material. The reinforcement layer material and the high temperature resistant soft material of the present disclosure cooperate with each other to obtain a cavity surface layer with properties of both hard and soft, strong and tough, which can fully release the large tensile stress that may occur on the surface of the die cavity during the welding process and under the service conditions of the die, so as to avoid hot cracks during welding process and service process.