Abstract: A front suspension device comprises a suspension arm, one end of which has a front-wheel support portion to support a front wheel of a vehicle and the other end of which is positioned on an inward side, in a vehicle width direction, of the front-wheel support portion and has a vehicle-body attachment portion to be attached to a vehicle-body member of the vehicle and a damper supported at a damper support portion which is provided at a portion of the suspension arm which is positioned in the vicinity of the front-wheel support portion at a lower portion thereof and connected to the vehicle-body member at an upper portion thereof. The damper support portion of the suspension arm has a breakage ease portion to cause breakage of the suspension arm.

Abstract: A faulted condition determination method is designed to detect a chromium content and a nickel content in a predetermined boundary region proximate to a boundary between a high-strength ferrite steel and a weld material in a welded joint in which the high-strength ferrite steel and another steel are welded together using the weld material containing nickel and to thereby determine the faulted condition of the predetermined boundary region based on the chromium content and the nickel content. Accordingly, it is possible to appropriately determine the faulted condition of welding of a replacement part in which a high-strength ferrite steel and another steel are welded together using a nickel-based weld material.

Abstract: The invention provides a ferritic heat-resistant steel whose creep rupture ductility in a long-term region is improved without detrimental to creep strengths. The ferritic heat-resistant steel has a chemical composition comprising, in % by mass, C: 0.03 to 0.15, Si: 0 to 0.8, Mn: 0.1 to 0.8, Cr: 8.0 to 11.5, Mo: 0.2 to 1.5, (W: 0.4 to 3.0), V: 0.1 to 0.4, Nb: 0.02 to 0.12 N: 0.02 to 0.10 with the balance of iron and inevitable impurities. This steel has a tempered martensite microstructure, and has an improved creep rupture ductility even when there is a load within the elastic limits at temperatures at which the ferritic heat-resistant steel is used, because internal strain or internal stress induced by martensitic transformation is relaxed or released by an intermediate tempering heat treatment in a two-phase state temperature in which a portion of an austenitic phase undergoes martensitic transformation.

Abstract: A faulted condition determination method is designed to detect a chromium content and a nickel content in a predetermined boundary region proximate to a boundary between a high-strength ferrite steel and a weld material in a welded joint in which the high-strength ferrite steel and another steel are welded together using the weld material containing nickel and to thereby determine the faulted condition of the predetermined boundary region based on the chromium content and the nickel content. Accordingly, it is possible to appropriately determine the faulted condition of welding of a replacement part in which a high-strength ferrite steel and another steel are welded together using a nickel-based weld material.

Abstract: The invention provides a ferritic heat-resistant steel whose creep rupture ductility in a long-term region is improved without detrimental to creep strengths. The ferritic heat-resistant steel has a chemical composition comprising, in % by mass, C: 0.03 to 0.15, Si: 0 to 0.8, Mn: 0.1 to 0.8, Cr: 8.0 to 11.5, Mo: 0.2 to 1.5, (W: 0.4 to 3.0), V: 0.1 to 0.4, Nb: 0.02 to 0.12 N: 0.02 to 0.10 with the balance of iron and inevitable impurities. This steel has a tempered martensite microstructure, and has an improved creep rupture ductility even when there is a load within the elastic limits at temperatures at which the ferritic heat-resistant steel is used, because internal strain or internal stress induced by martensitic transformation is relaxed or released by an intermediate tempering heat treatment in a two-phase state temperature in which a portion of an austenitic phase undergoes martensitic transformation.

Abstract: A heat-resistant component for a chemical processing apparatus is formed from a ferritic Cr-steel that contains Cr in an amount of from 13% by weight to 30% by mass. The ferritic Cr-steel has a creep rate of 1×10?51h or less at 700° C. under stress of 100 MPa, and an oxidation weight gain of 10 mg/cm2 or less after being maintained in a 650° C. water vapor for 1,000 h. The heat-resistant component for a chemical processing apparatus is produced by hot working the ferritic Cr-steel in a temperature range of 850 to 1,200° C., forming the ferritic Cr-steel into a component shape, subjecting the steel to an annealing treatment in a temperature range of 1,000 to 1,250° C., and cooling the steel to 400° C. or less at a cooling rate of 100° C./min or higher.

Abstract: A ferritic Cr-steel for a heat-resistant precision component contains Cr in an amount of from 13% by mass to 30% by mass, and has a thermal expansion coefficient of 15×10?6 or less in a temperature range of from room temperature to 800° C., and a minimum creep rate of 1×10?4/h or less at 700° C. under stress of 100 MPa. The ferritic Cr-steel for a heat-resistant precision component is produced by hot working a ferritic Cr-steel in a temperature range of 850 to 1,200° C., forming the ferritic Cr-steel into a predetermined shape, subjecting the steel to an annealing treatment in a temperature range of 1,000 to 1,250° C., and cooling the steel to 400° C. or less at a cooling rate of 100° C./min or higher. The production of the ferritic Cr-steel realizes a heat-resistant precision component, such as the rotor, disc, and blade of a turbine, that can withstand use under high temperatures above 600° C.

Abstract: A high temperature bolt material, characterized in that it is a ferrite steel comprising 8 wt % or more of Cr and having a tempered martensite structure and can be used in a high temperature region of higher than 500° C.; and a method for producing the high temperature bolt material which comprises subjecting the above-mentioned steel material to a heat treatment comprising a quenching or normalizing at a temperature of 1000° C. or higher and then to a tempering at a temperature of 730° C. or higher. The above ferrite steel high temperature bolt material is excellent in characteristics of the resistance to stress relaxation.