A dual-hardness clad steel plate. One surface of the steel plate is a high-hardness layer, the other surface of the steel plate is a low-hardness layer, and a combination of atoms is achieved between the high-hardness layer and the low-hardness layer by rolling bonding, wherein Mn13 steel is adopted for the low-hardness layer, and the Brinell hardness of the high-hardness layer is greater than 600. Further disclosed is a production method of the dual-hardness clad steel plate, comprising: 1) respectively preparing a high-hardness layer slab and a low-hardness layer slab; 2) assembling: preprocessing combined faces of the slabs, carrying out peripheral welded sealing on joint faces of the slabs, and carrying out vacuumizing treatment on a composite slab after welded sealing; 3) heating; 4) carrying out composite rolling; 5) cooling; and 6) carrying out thermal treatment, wherein the heating temperature is 1050-1100 C., the heating time is 2-3 min/mmslab thickness, and water cooling is performed on the heated slab, and the water temperature is lower than 40 C. The steel plate has different hardness characteristics and good low-temperature toughness

The disclosure relates to a process for the manufacture of a steel component comprising a fine-grained martensite structure component. The process comprises the steps of providing a steel component having an initial steel composition; introducing nitrogen into the steel component at a temperature T1 above 950? C., thereby creating an at least partly austenitic nitrogen-containing steel component; bringing the at least partly austenitic nitrogen-containing steel component to a temperature T2, such that austenite is decomposed into a steel component comprising at least an amount of carbon- and/or nitrogen-containing precipitates; bringing the steel component comprising at least an amount of carbon- and/or nitrogen-containing precipitates to a temperature T3 which is above T2, thereby creating an at least partly austenitic nitrogen-containing steel component optionally comprising at least an amount of carbon- and/or nitrogen-containing precipitates; and bringing the at least partly austenitic nitrogen-containing steel component to a temperature T4 that is below a martensite start temperature of the at least partly austenitic nitrogen-containing steel component for initiating transformation of at least some of the austenite into fine-grained martensite, thereby producing a steel component comprising a fine-grained martensite structure component.

A dual hardness steel article comprises a first air hardenable steel alloy having a first hardness metallurgically bonded to a second air hardenable steel alloy having a second hardness. A method of manufacturing a dual hard steel article comprises providing a first air hardenable steel alloy part comprising a first mating surface and having a first part hardness, and providing a second air hardenable steel alloy part comprising a second mating surface and having a second part hardness. The first air hardenable steel alloy part is metallurgically secured to the second air hardenable steel alloy part to form a metallurgically secured assembly, and the metallurgically secured assembly is hot rolled to provide a metallurgical bond between the first mating surface and the second mating surface.

A dual hardness steel article comprises a first air hardenable steel alloy having a first hardness metallurgically bonded to a second air hardenable steel alloy having a second hardness. A method of manufacturing a dual hard steel article comprises providing a first air hardenable steel alloy part comprising a first mating surface and having a first part hardness, and providing a second air hardenable steel alloy part comprising a second mating surface and having a second part hardness. The first air hardenable steel alloy part is metallurgically secured to the second air hardenable steel alloy part to form a metallurgically secured assembly, and the metallurgically secured assembly is hot rolled to provide a metallurgical bond between the first mating surface and the second mating surface.

The invention discloses a steel plate resistant to zinc-induced crack and a manufacturing method therefor. A low-alloy steel subjected to low C-ultra low Si-high Mn-low Al(Ti+Nb) microalloying treatment is taken as a basis; the Al content in the steel is appropriately reduced; the conditions are controlled so that Mn/C15, [(% Mn)+0.75(% Mo)](% C)0.16, Nb/Ti1.8 and Ti/N is between 1.50 and 3.40, CEZ0.44% and the B content is 2 ppm, Ni/Cu1.50; a Ca treatment is performed and the Ca/S ratio is controlled between 1.0 and 3.0, with (% Ca)(% S).sup.0.281.010.sup.3; and a TMCP process is optimized, so that a finished steel plate has a micro-structure of ferrite+bainite colonies which are tiny and dispersedly distributed, with an average grain size of not greater than 10 m, has homogeneous and excellent mechanical properties, excellent weldability and zinc-induced crack resistance, and is thus especially suitable as a zinc-spray coated corrosion-resistant steel plate for marine structures, a zinc-spray corrosion-resistant steel plate for extra-high voltage power transmission structures, a zinc-spray coated corrosion-resistant steel plate for coast bridge structures, and the like.

The invention discloses a steel plate resistant to zinc-induced crack and a manufacturing method therefor. A low-alloy steel subjected to low C-ultra low Si-high Mn-low Al(Ti+Nb) microalloying treatment is taken as a basis; the Al content in the steel is appropriately reduced; the conditions are controlled so that Mn/C15, [(% Mn)+0.75(% Mo)](% C)0.16, Nb/Ti1.8 and Ti/N is between 1.50 and 3.40, CEZ0.44% and the B content is 2 ppm, Ni/Cu1.50; a Ca treatment is performed and the Ca/S ratio is controlled between 1.0 and 3.0, with (% Ca)(% S).sup.0.281.010.sup.3; and a TMCP process is optimized, so that a finished steel plate has a micro-structure of ferrite+bainite colonies which are tiny and dispersedly distributed, with an average grain size of not greater than 10 m, has homogeneous and excellent mechanical properties, excellent weldability and zinc-induced crack resistance, and is thus especially suitable as a zinc-spray coated corrosion-resistant steel plate for marine structures, a zinc-spray corrosion-resistant steel plate for extra-high voltage power transmission structures, a zinc-spray coated corrosion-resistant steel plate for coast bridge structures, and the like.

A bulletproof steel plate with a tensile strength of 2000 MPa grade and a Brinell Hardness of 600 grade and a manufacturing method thereof, characterized by that the chemical elements in mass percentage thereof being: 0.35-0.45% of C, 0.80-1.60% of Si, 0.3-1.0% of Mn, 0.02-0.06% of Al, 0.3-1.2% of Ni, 0.30-1.00% of Cr, 0.20-0.80% of Mo, 0.20-0.60% of Cu, 0.01-0.05% of Ti, 0.001-0.003% of B, and the balance being Fe and inevitable impurities. The tensile strength of the steel plate can reach a grade of 2000 MPa and its Brinell Hardness can reach a grade of 600.

A bulletproof steel plate with a tensile strength of 2000 MPa grade and a Brinell Hardness of 600 grade and a manufacturing method thereof, characterized by that the chemical elements in mass percentage thereof being: 0.35-0.45% of C, 0.80-1.60% of Si, 0.3-1.0% of Mn, 0.02-0.06% of Al, 0.3-1.2% of Ni, 0.30-1.00% of Cr, 0.20-0.80% of Mo, 0.20-0.60% of Cu, 0.01-0.05% of Ti, 0.001-0.003% of B, and the balance being Fe and inevitable impurities. The tensile strength of the steel plate can reach a grade of 2000 MPa and its Brinell Hardness can reach a grade of 600.

One aspect of the present disclosure is directed to low-alloy steels exhibiting high hardness and an advantageous level of multi-hit ballistic resistance with minimal crack propagation imparting a level of ballistic performance suitable for military armor applications. Certain embodiments of the steels according to the present disclosure have hardness in excess of 550 HBN and demonstrate a high level of ballistic penetration resistance relative to conventional military specifications.

One aspect of the present disclosure is directed to low-alloy steels exhibiting high hardness and an advantageous level of multi-hit ballistic resistance with minimal crack propagation imparting a level of ballistic performance suitable for military armor applications. Certain embodiments of the steels according to the present disclosure have hardness in excess of 550 HBN and demonstrate a high level of ballistic penetration resistance relative to conventional military specifications.