An ultra-heavy steel plate with low cracking sensitivity and low yield ratio, the mass percentages of chemical components of the steel plate are C 0.05-0.09; Si 0.2-0.4; Mn 1.3-1.6; Al 0.02-0.04; Nb 0.03-0.08; V 0.03-0.08; Cr 0.1-0.5; Ni 0.1-0.5; Mo 0.1-0.3; Cu 0.2-0.5; Ti 0.01-0.02; P0.015; S0.003; N0.007, the balance being Fe and inevitable impurities; the carbon equivalent is 0.43, the cold cracking sensitivity coefficient Pcm is 0.20. A low cracking sensitivity and low yield ratio steel plate with a thickness of 40-70 mm is manufactured by the process steps of KR molten iron pretreatment-converter smelting-LF refining-RH vacuum degassing-continuous casting-lid-covering slow cooling for the continuous casting slabs-casting slabs heating-controlled rolling-controlled cooling-hot straightening-air cooling and so on.

Steel has a chemical composition that contains 0.050% to 0.40% of C, 0.50% to 3.0% of Si, 3.0% to 8.0% of Mn, and 0.001% to 3.0% of sol. Al, by mass %, and has a metallographic structure that contains 10% to 40% of austenite in terms of % by volume. The average concentration of C in austenite is 0.30% by 0.60%, by mass %, structure uniformity, which is represented by a value obtained by subtracting the minimum value from the maximum value of Vickers hardness that is measured, in the metallographic structure is 30 Hv or less, and the tensile strength is 900 MPa to 1800 MPa.

A method of manufacturing a component, the method including a maraging steel blank with an initial shape; and performing an incremental cold forming operation on the maraging steel blank, wherein the incremental cold forming operation reduces a thickness of the maraging steel blank.

Provided are an austenitic stainless steel that has high strength and favorable shape retention properties after a heat treatment, and a production method thereof. One aspect of the present invention is the austenitic stainless steel wherein a component composition satisfies C: less than or equal to 0.12% by mass; Si: greater than or equal to 0.1% by mass and less than or equal to 1.0% by mass; Mn: greater than or equal to 0.1% by mass and less than or equal to 3.0% by mass; P: less than or equal to 0.05% by mass; S: less than or equal to 0.01% by mass; Cr: greater than or equal to 13.0% by mass and less than or equal to 22.0% by mass; Ni: greater than or equal to 4.0% by mass and less than or equal to 12.0% by mass; Cu: greater than or equal to 0.01% by mass and less than or equal to 0.50% by mass; Mo: less than or equal to 5.0% by mass; Al: less than or equal to 0.03% by mass; Nb: greater than or equal to 0.05% by mass and less than or equal to 0.30% by mass; N: greater than or equal to 0.10% by mass and less than or equal to 0.50% by mass; and a balance consisting of Fe and inevitable impurities, and a crystal grain size number is greater than or equal to 7.0.

A martensitic alloy component includes by weight, 0.25% to 0.31% carbon (C), 2.1% to 3.0% manganese (Mn), 0.22% to 0.28% silicon (Si), 2.0% to 2.2% chromium (Cr), 0.45% to 0.55% molybdenum (Mo), 0.08% to 0.12% vanadium (V), and the balance is iron (Fe) and incidental impurities. The manganese-chromium martensitic alloy component has a hardenability corresponding to an ideal diameter of about 15 inches to about 30 inches or more.

A kind of steel is able to achieve a high elongation with the steel used for hot stamping by means of simple hot stamping process. The formed component has excellent yield strength, tensile strength and elongation. The steel used for hot stamping comprises by weight percent 0.1-0.19% of C, 5.09-9.5% of Mn, 0.11-0.4% of V, and 0-2% Si+Al, wherein the combination of C and V meets one of the following two requirements: 1) 0.1-0.17% of C and 0.11-0.4% of V; and 2) 0.171-0.19% of C and 0.209-0.4% of V.

An iron-based alloy includes, in weight percent, carbon from about 1 to about 2 percent; manganese from about 0.1 to about 1 percent; silicon from about 0.1 to about 2.5 percent; chromium from about 11 to about 19 percent; nickel up to about 8 percent; vanadium from about 0.8 to about 5 percent; molybdenum from about 11 to about 19 percent; tungsten up to about 0.5 percent; niobium from about 1 to about 4 percent; cobalt up to about 5.5 percent; boron up to about 0.5 percent; nitrogen up to about 0.5 percent, copper up to about 1.5 percent, sulfur up to about 0.3 percent, phosphorus up to about 0.3 percent, up to about 5 percent total of tantalum, titanium, hafnium and zirconium; iron from about 50 to about 70 percent; and incidental impurities. The alloy is suitable for use in elevated temperature applications such as in valve seat inserts for combustion engines.

An iron-based alloy includes, in weight percent, carbon from about 1 to about 2 percent; manganese from about 0.1 to about 1 percent; silicon from about 0.1 to about 2.5 percent; chromium from about 11 to about 19 percent; nickel up to about 8 percent; vanadium from about 0.8 to about 5 percent; molybdenum from about 11 to about 19 percent; tungsten up to about 0.5 percent; niobium from about 1 to about 4 percent; cobalt up to about 5.5 percent; boron up to about 0.5 percent; nitrogen up to about 0.5 percent, copper up to about 1.5 percent, sulfur up to about 0.3 percent, phosphorus up to about 0.3 percent, up to about 5 percent total of tantalum, titanium, hafnium and zirconium; iron from about 50 to about 70 percent; and incidental impurities. The alloy is suitable for use in elevated temperature applications such as in valve seat inserts for combustion engines.

The present invention provides an age hardening type bainitic microalloyed steel having a composition which includes, in terms of mass %: 0.06-0.35% of C; 0.01-2.00% of Si; 0.10-3.00% of Mn; 0.001-0.200% of S; 0.001-2.00% of Cu; 0.40-3.00% of Ni; 0.10-3.00% of Cr; 0.10-1.00% of Mo; 0.10-1.00% of V; and 0.001-0.100% of s-Al, with the remainder being Fe and unavoidable impurities, and which satisfies a value of the following expression (1) to be 20 or larger and a value of the following expression (2) to be 0.82 or larger:
3[C]+10[Mn]+2[Cu]+2[Ni]+12[Cr]+9[Mo]+2[V]expression (1);
1.66[C]+0.18[Si]+0.27[Mn]+0.09[Ni]+0.32[Cr]+0.34[Mo]+0.44[V]expression (2),
in which each [ ] in the expression (1) and the expression (2) indicates a content of the element shown therein in terms of mass %.

The present invention provides an age hardening type bainitic microalloyed steel having a composition which includes, in terms of mass %: 0.06-0.35% of C; 0.01-2.00% of Si; 0.10-3.00% of Mn; 0.001-0.200% of S; 0.001-2.00% of Cu; 0.40-3.00% of Ni; 0.10-3.00% of Cr; 0.10-1.00% of Mo; 0.10-1.00% of V; and 0.001-0.100% of s-Al, with the remainder being Fe and unavoidable impurities, and which satisfies a value of the following expression (1) to be 20 or larger and a value of the following expression (2) to be 0.82 or larger:
3[C]+10[Mn]+2[Cu]+2[Ni]+12[Cr]+9[Mo]+2[V]expression (1);
1.66[C]+0.18[Si]+0.27[Mn]+0.09[Ni]+0.32[Cr]+0.34[Mo]+0.44[V]expression (2),
in which each [ ] in the expression (1) and the expression (2) indicates a content of the element shown therein in terms of mass %.