A hollow shaft includes a cylindrical main body part and an extremity drawn part that is integrally connected to one end of the main body part on the same axis and whose diameter is made smaller than a diameter of the main body part by drawing processing, wherein an inner peripheral face of the main body part and an inner peripheral face of a base portion, which is continuous with one end side of the main body part, of the extremity drawn part are formed as cut faces that are subjected to cutting processing before the drawing processing, and an inner peripheral face of a tip portion, which is continuous with an extremity side of the base portion, of the extremity drawn part is a non-cut face. Accordingly, the hollow shaft can be molded with high shape precision while maintaining a low drawing ratio for an extremity drawn part.

The present disclosure relates to a copper foil that exhibits surprising low repulsive force characteristics; and to methods for manufacturing such copper foils. Typically, the copper foil has (a) a lightness L* value of the nodule untreated side, based on the L*a*b color system, in the range of 75 to 90 and (b) a normal tensile strength in the range of 40 kgf/mm.sup.2 to 55 kgf/mm.sup.2. The disclosure further relates to flexible printed circuit boards and electronic devices using the above-mentioned copper foils for forming conductive lines therein.

Provided are an electrodeposited copper foil, a negative electrode that is for a lithium ion secondary battery, and a lithium ion secondary battery into which the electrode is incorporated. The electrodeposited copper foil exhibits good electrical conductivity and superior tensile strength, with no significant decline in tensile strength exhibited even after one hour of heating at 300 C. The negative electrode has heightened cycle properties due to the use of the electrodeposited copper foil as a current collector. Using x-ray diffraction, in the electrodeposited copper foil, in normal conditions, the diffraction intensity (I)<220> in the <220> orientation, the diffraction intensity (I)<200> in the <200> orientation, and the diffraction intensity (I)<111> in the <111> orientation, satisfy the following formula (1):
I<220>/{I<220>+I<200>+I<111>}>0.13(1).

Disclosed is a semi-amorphous, ductile brazing foil with a composition consisting essentially of Ni.sub.balFe.sub.aCr.sub.bP.sub.cSi.sub.dB.sub.eMo.sub.f with approximately 30 atomic percent aapproximately 70 atomic percent; approximately 0 atomic percent bapproximately 20 atomic percent; approximately 9 atomic percent capproximately 16 atomic percent; approximately 0 atomic percent dapproximately 4 atomic percent; eapproximately 2 atomic percent; fapproximately 5 atomic percent; and the balance being Ni and other impurities; where c+d+e<approximately 16 atomic percent.

A heat exchanger tube has a tube end having two extended portions substantially opposite the other around the periphery of the tube end, and two shortened portions, each positioned between the two extended portions and substantially opposite the other around the periphery of the tube end. The tube end may be formed by removing opposite portions of the tube by cutting a disc-shaped portion with a generally smoothly curving periphery along a major portion of the width of the tube. Each tube is oriented within an opening in the header wall of a heat exchanger assembly having a header portion integral with a tank portion, such that the tube end two extended portions are oriented substantially perpendicular to the direction of fluid flow within the header and the tube end two shorter portions are oriented substantially in the direction of fluid flow in order to reduce interference with fluid flow.

A heat exchanger tube has a tube end having two extended portions substantially opposite the other around the periphery of the tube end, and two shortened portions, each positioned between the two extended portions and substantially opposite the other around the periphery of the tube end. The tube end may be formed by removing opposite portions of the tube by cutting a disc-shaped portion with a generally smoothly curving periphery along a major portion of the width of the tube. Each tube is oriented within an opening in the header wall of a heat exchanger assembly having a header portion integral with a tank portion, such that the tube end two extended portions are oriented substantially perpendicular to the direction of fluid flow within the header and the tube end two shorter portions are oriented substantially in the direction of fluid flow in order to reduce interference with fluid flow.

Disclosed is a semi-amorphous, ductile brazing foil with a composition consisting essentially of Ni.sub.balFe.sub.aCr.sub.bP.sub.cSi.sub.dB.sub.eMo.sub.f with approximately 30 atomic percentaapproximately 38 atomic percent; approximately 10 atomic percentbapproximately 20 atomic percent; approximately 7 atomic percentcapproximately 20 atomic percent; approximately 2 atomic percentdapproximately 4 atomic percent; eapproximately 2 atomic percent; fapproximately 5 atomic percent; and the balance being Ni and other impurities; where c+d+e<approximately 16 atomic percent.

Provided is a plastic working method of steel including austenite, the method including: analyzing a strain ratio x of an estimated breaking point which is specified during plastic deformation of the steel; heating a steel such that a local temperature T.sub.local is within a temperature range indicated by the following expression 1, when T.sub.x represents a strain-induced-transformation-maximum-ductility-temperature in the unit of C. for the strain ratio x, L.sub.x represents the standard deviation of a fitted curve of critical equivalent strain which depends on the strain ratio x on a lower temperature side than T.sub.x, H.sub.x represents the standard deviation of a fitted curve of critical equivalent strain which depends on the strain ratio x on a higher temperature side than T.sub.x, and T.sub.local represents a local temperature in the unit of C. of the estimated breaking point; and plastically deforming the steel after heating:
T.sub.x2L.sub.xT.sub.localT.sub.x+1.25H.sub.x(Expression 1).

Provided is a plastic working method of steel including austenite, the method including: analyzing a strain ratio x of an estimated breaking point which is specified during plastic deformation of the steel; heating a steel such that a local temperature T.sub.local is within a temperature range indicated by the following expression 1, when T.sub.x represents a strain-induced-transformation-maximum-ductility-temperature in the unit of C. for the strain ratio x, L.sub.x represents the standard deviation of a fitted curve of critical equivalent strain which depends on the strain ratio x on a lower temperature side than T.sub.x, H.sub.x represents the standard deviation of a fitted curve of critical equivalent strain which depends on the strain ratio x on a higher temperature side than T.sub.x, and T.sub.local represents a local temperature in the unit of C. of the estimated breaking point; and plastically deforming the steel after heating:
T.sub.x2L.sub.xT.sub.localT.sub.x+1.25H.sub.x(Expression 1).

A copper foil composite comprising a copper foil and a resin layer laminated thereon, satisfying an equation 1: (f.sub.3t.sub.3)/(f.sub.2t.sub.2)=>1 wherein t.sub.2 (mm) is a thickness of the copper foil, f.sub.2 (MPa) is a stress of the copper foil under tensile strain of 4%, t.sub.3 (mm) is a thickness of the resin layer, f.sub.3 (MPa) is a stress of the resin layer under tensile strain of 4%, and an equation 2: 1<=33f.sub.1/(FT) wherein f.sub.1 (N/mm) is 180 peeling strength between the copper foil and the resin layer, F(MPa) is strength of the copper foil composite under tensile strain of 30%, and T (mm) is a thickness of the copper foil composite, wherein a Sn layer having a thickness of 0.2 to 3.0 m is formed on a surface of the copper foil on which the resin layer is not laminated.