Abstract: A stainless steel that includes chromium and other alloying element as a plurality of alloying elements including: a base material layer including chromium of a specified chromium content necessary for forming a passive film or more; and a superficial layer including chromium at a lower chromium content than the chromium content contained in the base material layer, and the superficial layer including the other alloying elements at a same content of the other alloying element as the content of the other alloying element contained in the base material layer.

Abstract: The problem of the present invention involves providing a gear that has high tooth-root bending strength and for which there is no chipping of the tips of the teeth. Accordingly, the surface of the gear is carburized and the gear is strengthened by imparting residual stress, with the residual stress in the region with a surface depth of 5 ?m to 20 ?m being ?1000 MPa or less, and the residual stress in the region with a surface depth of 50 ?m to 150 ?m being ?1000 MPa or greater.

Abstract: A stainless steel that includes chromium and other alloying element as a plurality of alloying elements including: a base material layer including chromium of a specified chromium content necessary for forming a passive film or more; and a superficial layer including chromium at a lower chromium content than the chromium content contained in the base material layer, and the superficial layer including the other alloying elements at a same content of the other alloying element as the content of the other alloying element contained in the base material layer.

Abstract: The problem of the present invention involves providing a gear that has high tooth-root bending strength and for which there is no chipping of the tips of the teeth. Accordingly, the surface of the gear is carburized and the gear is strengthened by imparting residual stress, with the residual stress in the region with a surface depth of 5 ?m to 20 ?m being ?1000 MPa or less, and the residual stress in the region with a surface depth of 50 ?m to 150 ?m being 1000 MPa or greater.

Abstract: Disclosed is an exhaust system part having a high corrosion resistance, an EGR cooler using the exhaust system part, and a method of nitriding the exhaust system part. The exhaust system part made of a stainless steel and having an exhaust gas of an internal combustion engine flow therein, includes an upstream side end portion through which the exhaust gas is introduced, a downstream side end portion through which the exhaust gas is discharged, and a wall portion formed in an annular shape extending in the direction of the exhaust gas flow and disposed between the upstream side end portion and the downstream side end portion, in which a chromium oxide nitride film consisting of CrOxNy is formed on the inner peripheral surface of the wall portion.

Abstract: The problem of the present invention involves providing a gear that has high tooth-root bending strength and for which there is no chipping of the tips of the teeth. Accordingly, the surface of the gear is carburized and the gear is strengthened by imparting residual stress, with the residual stress in the region with a surface depth of 5 ?m to 20 ?m being ?1000 MPa or less, and the residual stress in the region with a surface depth of 50 ?m to 150 ?m being ?1000 MPa or greater.

Abstract: Provided are a steel having a non-magnetic portion, which can be applied to the steel of the remaining portion irrespective of the material and which has a structure of a short treating time required and a determined depth direction, its manufacturing method, and a revolving electric core. There is prepared an electromagnetic steel sheet having a recessed groove. A two-layered chip of a modifier metal foil and a stainless steel foil is so set in the groove of the electromagnetic steel sheet that the electromagnetic steel sheet and the stainless steel foil have surfaces of the same height. The modifier metal foil is melted when electric current is applied under pressure. When this pressing and current applying is continued, inner sides of the electromagnetic steel sheet and the stainless steel foil contacting the modifier metal foil are melted to form a nonmagnetic alloy layer in the region excepting the surface portions of an electromagnetic steel sheet layer and a stainless steel layer.

Abstract: The present invention can provide a method and an apparatus for bending a pipe whose bending cross section has reduced compressed ratio, reduced reduction ratio of area and reduced reduction in thickness and in which bending can be conducted at the desired curvature. In the present invention, both edges of the pipe bending portion are arrested and grasped, a center of one bending edge is set to be the axis and a revolution axis is amounted on it, a rotation axis is mounted at a center of the other bending edge and gears are installed on the revolution axis and the rotation axis so as to engage each other so that the driving is driven to the gear on the rotation axis. The rotation axis revolves having the radius to be the distance from the rotation axis to the revolution axis and at the same time the rotation axis rotates on its axis having the radius of the gear in response to the revolution angle.

Abstract: In a method and apparatus for manufacturing a corrugated tube, a tube is clamped by a pair of spaced apart chucks. A local portion of the tube is softened. The chucks are moved in the same direction such that the trailing or rearward chuck moves farther than the leading or forward chuck, thereby imparting an axially compressive force on the tube. Accordingly, a bulge is formed at the softened portion of the tube. The heating and compression cycle may be performed several times to obtain a corrugated tube having a plurality of bulges or waves formed therein.