A thick steel plate for high heat input welding and having great heat-affected area toughness and a manufacturing method therefor, comprising the steps of smelting, casting, rolling, and cooling. Also, the chemical composition of the steel plate satisfies 1Ti/N6 and (Ca+REM+Zr)/Al0.11, where the effective S content in steel=S-0.8Ca-0.34REM-0.35Zr. and the effective S content in steel: 0.0006-0.005%; finely dispersed inclusions may be formed, and the amount of composite inclusion CaO+Al.sub.2O.sub.3+MnS+TiN in the steel plate is at a proportion of 12%. With respect to welding in which the thickness of the steel plate is 50-70 mm, the tensile strength of a base material is 510 MPa. and welding input energy is 200-400 kJ/cm, the average Charpy impact work of a welding heat-affected area of the steel plate at 40 C. is 100 J or more, and at the same time, the average Charpy aging impact work of the base material of thickness at 40 C. is 46 J or more.

A method of heat treatment of a non-metallic or metallic item is provided. The method includes at least one step A) of heat transfer between the item and a heat transfer fluid A including a fluid medium and nanoparticles. The heat transfer fluid has a heat transfer coefficient above the heat transfer coefficient of water. The method also includes at least one step B) of heat transfer between the item and a heat transfer fluid B including a fluid medium and nanoparticles. The heat transfer fluid B has a heat transfer coefficient different from the heat transfer coefficient of A and above the heat transfer coefficient of water. The heat transfer fluids A and B are different.

A thick steel plate for high heat input welding and having great heat-affected area toughness and a manufacturing method therefor, comprising the steps of smelting, casting, rolling, and cooling. Chemical composition is properly controlled for the steel plate and satisfies 1Ti/N6 and Mg/Ti>0.017, where effective S content in steel=S1.3 Mg0.8 Ca0.34 REM0.35 Zr, and effective S content in steel: 0.0003-0.003%; finely dispersed inclusions may be formed in the steel plate, and the amount of composite inclusion MgO+Ti.sub.2O.sub.3+MnS in the steel plate is controlled at a proportion greater than or equal to 5%. The tensile strength of a base material so acquired is 510 MPa, insofar as welding input energy is 200400 kJ/cm, the average Charpy impact work of the steel plate at 40 C. is 100 J or more, at the same time, the average Charpy aging impact work of the base material of thickness at 40 C. is 46 J or more.

The stress corrosion cracking resistance of an aluminum alloy member consisting of 7000-series aluminum alloy extruded shape is improved. At least one region of a quenched aluminum alloy extruded shape is subjected to a restoring treatment of heating at a temperature-raising rate of 0.4 C./second or more, holding at a temperature ranging 300 to 590 C. for a time longer than zero second and cooling at a cooling rate of 0.5 C./second or more. A plastic working is applied to the region within 72 hours. The region is subjected to a heat treatment of heating at a temperature-raising rate of 0.4 C./second or more, holding at a temperature ranging 300 to 590 C. for a time longer than zero second and not longer than 300 seconds and cooling at a cooling rate of 2000 C./minute or less. The whole of the aluminum alloy extruded shape is subjected to an artificial aging treatment.

The stress corrosion cracking resistance of an aluminum alloy member consisting of 7000-series aluminum alloy extruded shape is improved. At least one region of a quenched aluminum alloy extruded shape is subjected to a restoring treatment of heating at a temperature-raising rate of 0.4 C./second or more, holding at a temperature ranging 300 to 590 C. for a time longer than zero second and cooling at a cooling rate of 0.5 C./second or more. A plastic working is applied to the region within 72 hours. The region is subjected to a heat treatment of heating at a temperature-raising rate of 0.4 C./second or more, holding at a temperature ranging 300 to 590 C. for a time longer than zero second and not longer than 300 seconds and cooling at a cooling rate of 2000 C./minute or less. The whole of the aluminum alloy extruded shape is subjected to an artificial aging treatment.

Low-alloy oil-well steel pipe includes a composition consisting, in mass %, of C: 0.40 to 0.65%, Si: 0.05 to 0.50%, Mn: 0.10 to 1.00%, P: 0.020% or less, S: 0.0020% or less, Cu: 0.15% or less, Cr: 0.40 to 1.50%, Mo: 0.50 to 2.50%, V: 0.05 to 0.25%, Ti: 0 to less than 0.01%, Nb: 0.01 to 0.2%, sol. Al: 0.010 to 0.100%, N: 0.006% or less, B: 0 to 0.0015%, and Ca: 0 to 0.003%, the balance being Fe and impurities. The structure has tempered martensite and 0 to less than 2% volume ratio of retained austenite. A grain size number of prior-austenite grain in the structure is 9.0 or more. An equivalent circular diameter of a sub-structure surrounded by a boundary having a crystal orientation difference of 15 or more from a packet boundary, a block boundary and a lath boundary is 3 m or less for the tempered martensite.

Low-alloy oil-well steel pipe includes a composition consisting, in mass %, of C: 0.40 to 0.65%, Si: 0.05 to 0.50%, Mn: 0.10 to 1.00%, P: 0.020% or less, S: 0.0020% or less, Cu: 0.15% or less, Cr: 0.40 to 1.50%, Mo: 0.50 to 2.50%, V: 0.05 to 0.25%, Ti: 0 to less than 0.01%, Nb: 0.01 to 0.2%, sol. Al: 0.010 to 0.100%, N: 0.006% or less, B: 0 to 0.0015%, and Ca: 0 to 0.003%, the balance being Fe and impurities. The structure has tempered martensite and 0 to less than 2% volume ratio of retained austenite. A grain size number of prior-austenite grain in the structure is 9.0 or more. An equivalent circular diameter of a sub-structure surrounded by a boundary having a crystal orientation difference of 15 or more from a packet boundary, a block boundary and a lath boundary is 3 m or less for the tempered martensite.

An endoprosthesis fabricated from multi-phase ferrous steel. Endoprostheses can include a variety of devices such as staples, orthodontic wires, heart valves, filter devices, and stents, many of which devices are diametrically expandable devices. Multi-phase ferrous steels include dual phase steels and transformation induced plasticity steels (TRIP steels).

An endoprosthesis fabricated from multi-phase ferrous steel. Endoprostheses can include a variety of devices such as staples, orthodontic wires, heart valves, filter devices, and stents, many of which devices are diametrically expandable devices. Multi-phase ferrous steels include dual phase steels and transformation induced plasticity steels (TRIP steels).

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.