A high-strength galvanized steel sheet includes a steel sheet having a chemical composition containing a predetermined component element, a mass ratio of a content of Si to a content of Mn in the steel (Si/Mn) being 0.1 or more and less than 0.2, and the balance: Fe and incidental impurities, and a steel structure in which an average grain size of inclusions containing at least one of Al, Si, Mg, and Ca and existing in an area extending from a surface to a position of ⅓ of a sheet thickness is 50 μm or less, and an average nearest distance between ones of the inclusions is 20 μm or more; and a galvanized layer provided on a surface of the steel sheet, in which an amount of diffusible hydrogen contained in the steel is less than 0.25 mass ppm, and a tensile strength is 1100 MPa or more.

A martensitic stainless steel contains 0.20 mass %≤C≤0.60 mass %, 0.10 mass %≤N≤0.50 mass %, 14.00 mass %≤Cr≤17.00 mass %, 1.00 mass %≤Mo≤3.00 mass %, 0.20 mass %≤V≤0.40 mass %, Si≤0.30 mass %, Mn≤0.80 mass %, P≤0.040 mass %, S≤0.040 mass %, Cu≤0.25 mass %, Ni≤0.20 mass %, and the balance Fe with inevitable impurities.

A martensitic stainless steel contains 0.20 mass %≤C≤0.60 mass %, 0.10 mass %≤N≤0.50 mass %, 14.00 mass %≤Cr≤17.00 mass %, 1.00 mass %≤Mo≤3.00 mass %, 0.20 mass %≤V≤0.40 mass %, Si≤0.30 mass %, Mn≤0.80 mass %, P≤0.040 mass %, S≤0.040 mass %, Cu≤0.25 mass %, Ni≤0.20 mass %, and the balance Fe with inevitable impurities.

This disclosure is related to high yield strength steel where mechanical properties, such as elongation, ultimate tensile strength and yield strength in a sheet are maintained or enhanced via thermal treatment optionally provided during a galvanization coating operation.

The disclosed martensitic stainless steel is defined in its composition is by specified ranges of weight percentages of C; Mn; Si; ≤Mn+Si; ≤S; 10,000×Mn×S; P; Cr, with [Cr−10.3−80*(C+N).sup.2]≤(Mn+Ni); Ni; Mo; Mo+2W; Cu; Ti; V; Zr; Al; O; Ta; Nb; (Nb+Ta)/(C+N); Nb; N; Co; Cu+Co; Cu+Co+Ni; B; rare earths+Y; Ca; the remainder being iron and impurities resulting from processing. Its microstructure includes at least 75% martensite, at most 20% ferrite and at most 0.5% carbides, the size of the ferrite grains being between 4 and 80 μm, preferably between 5 and 40 μm. Also disclosed is a method of manufacturing such steel.

The disclosed martensitic stainless steel is defined in its composition is by specified ranges of weight percentages of C; Mn; Si; ≤Mn+Si; ≤S; 10,000×Mn×S; P; Cr, with [Cr−10.3−80*(C+N).sup.2]≤(Mn+Ni); Ni; Mo; Mo+2W; Cu; Ti; V; Zr; Al; O; Ta; Nb; (Nb+Ta)/(C+N); Nb; N; Co; Cu+Co; Cu+Co+Ni; B; rare earths+Y; Ca; the remainder being iron and impurities resulting from processing. Its microstructure includes at least 75% martensite, at most 20% ferrite and at most 0.5% carbides, the size of the ferrite grains being between 4 and 80 μm, preferably between 5 and 40 μm. Also disclosed is a method of manufacturing such steel.

Method for producing a precoated steel blank including the successive steps of: —providing a precoated steel strip including a steel substrate having, on at least one of its main faces, a precoating, the precoating including an intermetallic alloy layer and a metallic layer extending atop said intermetallic alloy layer, the metallic layer being a layer of aluminum, a layer of aluminum alloy or a layer of aluminum-based alloy, —laser cutting the precoated steel strip in order to obtain at least one precoated steel blank, the precoated steel blank including a laser cut edge surface resulting from the laser cutting operation, the laser cut edge surface including a substrate portion and a precoating portion, wherein the laser cutting is carried out in such a way that the substrate portion of the laser cut edge directly resulting from the cutting operation has an oxygen content greater than or equal to 15% in weight.

Method for producing a precoated steel blank including the successive steps of: —providing a precoated steel strip including a steel substrate having, on at least one of its main faces, a precoating, the precoating including an intermetallic alloy layer and a metallic layer extending atop said intermetallic alloy layer, the metallic layer being a layer of aluminum, a layer of aluminum alloy or a layer of aluminum-based alloy, —laser cutting the precoated steel strip in order to obtain at least one precoated steel blank, the precoated steel blank including a laser cut edge surface resulting from the laser cutting operation, the laser cut edge surface including a substrate portion and a precoating portion, wherein the laser cutting is carried out in such a way that the substrate portion of the laser cut edge directly resulting from the cutting operation has an oxygen content greater than or equal to 15% in weight.

The present invention discloses to a Hot-work die steel electroslag remelted ingot and a manufacture method thereof. The electroslag remelted ingot comprises the following chemical components, C: 0.36-0.41%, Si: 0.80-1.10%, Mn: 1.00-3.00%, Cr: 4.90-5.40%, Mo: 1.35-1.55%, V: 0.4-0.7%, Ni≤0.04%, Cu≤0.04%%, S≤0.003%, P≤0.012%, O≤0.0015%, H≤0.0002%, N≤0.006%, 0.05%≤RE≤0.20%, the balance being Fe. The above percentage is percentage by mass. According to the present invention, the features of electroslag remelting under inert gas protection are fully combined and a rare earth alloy is precisely fed during the electroslag remelting, thus exerting the excellent effects of RE inclusion modification and micro-alloying under high purity and high uniformity conditions and realizing high-quality and high-performance Hot-work die steel.

The present invention discloses to a Hot-work die steel electroslag remelted ingot and a manufacture method thereof. The electroslag remelted ingot comprises the following chemical components, C: 0.36-0.41%, Si: 0.80-1.10%, Mn: 1.00-3.00%, Cr: 4.90-5.40%, Mo: 1.35-1.55%, V: 0.4-0.7%, Ni≤0.04%, Cu≤0.04%%, S≤0.003%, P≤0.012%, O≤0.0015%, H≤0.0002%, N≤0.006%, 0.05%≤RE≤0.20%, the balance being Fe. The above percentage is percentage by mass. According to the present invention, the features of electroslag remelting under inert gas protection are fully combined and a rare earth alloy is precisely fed during the electroslag remelting, thus exerting the excellent effects of RE inclusion modification and micro-alloying under high purity and high uniformity conditions and realizing high-quality and high-performance Hot-work die steel.