Process for manufacturing seamless steel pipe

There are provided: a seamless steel pipe formed from a cylindrical steel material billet through a hot isostatic extrusion step, wherein a depth of a contiguous flaw formed on an inner periphery surface and an outer periphery surface of the steel pipe is 50 µm or less; a hollow spring obtained by f...

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Bibliographische Detailangaben
Hauptverfasser:	Takamura, Noritoshi, Iwaya, Koji, Toyotake, Kotaro, Minami, Tomoyuki
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	ALLOYS AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKINGWITHOUT ESSENTIALLY REMOVING MATERIAL BLASTING CHEMISTRY ENGINEERING ELEMENTS AND UNITS FERROUS OR NON-FERROUS ALLOYS GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS HEATING LIGHTING MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES,OTHERWISE THAN BY ROLLING MEANS FOR DAMPING VIBRATION MECHANICAL ENGINEERING MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL METALLURGY METALLURGY OF IRON MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS PERFORMING OPERATIONS PUNCHING METAL ROLLING OF METAL SHOCK-ABSORBERS SPRINGS THERMAL INSULATION IN GENERAL TRANSPORTING TREATMENT OF ALLOYS OR NON-FERROUS METALS WEAPONS WORKING OR PROCESSING OF METAL WIRE
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Beschreibung
Zusammenfassung:	There are provided: a seamless steel pipe formed from a cylindrical steel material billet through a hot isostatic extrusion step, wherein a depth of a contiguous flaw formed on an inner periphery surface and an outer periphery surface of the steel pipe is 50 µm or less; a hollow spring obtained by forming a hollow body in a shape of a coil or a bar or a bar with curved part from the seamless steel pipe made of spring steel and applying a surface treatment to the hollow body so that the hollow body has compressive residual stress; and a method for producing seamless steel pipe including: a billet molding step; a first heating step; a hot isostatic extrusion step; a second heating step; an extension step; a third heating step; and a pickling step.