Methods for producing blank tube for cold drawing and for producing cold drawn tube

A method for producing a blank tube for cold drawing, wherein the blank tube before drawing is provided with an oil lubrication film on a surface thereof and the blank tube is used in a high-pressure lubrication drawing, the method comprising:

• subjecting a starting material which is produced in a hot working method to a bright heat treatment;
• cold rolling the starting material to produce a workpiece which has an outer diameter and wall thickness for cold drawing to be applied thereto;
• subjecting an inner surface of the workpiece to a blasting treatment by use of blast grains of #100 to #350 in microgrits classification defined in ISO 8486 1996 F standard to obtain the blank tube before drawing,
• wherein the inner surface roughness of the blank tube before drawing, when represented by an average surface roughness Ra defined in ANSI B46.1, satisfies formula (i) below,
• 0.10 μm≦Ra≦1.00 μm (i).

A method for producing a blank tube for cold drawing, wherein the blank tube before drawing is provided with an oil lubrication film on a surface thereof and the blank tube is used in a high-pressure lubrication drawing, the method comprising:

• subjecting a starting material which is produced in a hot working method to a bright heat treatment;
• cold rolling the starting material to produce a workpiece which has an outer diameter and wall thickness for cold drawing to be applied thereto;
• subjecting an inner surface of the workpiece to a blasting treatment by use of blast grains of #200 to #350 in microgrits classification defined in ISO 8486 1996 F standard, the blast grains being made of zirconium oxide, to obtain the blank tube before drawing,
• wherein the inner surface roughness of the blank tube before drawing, when represented by an average surface roughness Ra defined in ANSI B46.1, satisfies formula (ii) below,
• 0.10 μm≦Ra≦0.50 μm (ii).

A method for producing a blank tube for cold drawing, wherein the blank tube before drawing is provided with an oil lubrication film on a surface thereof and the blank tube is used in a high-pressure lubrication drawing, the method comprising:

• subjecting a starting material which is produced in a hot working method to a bright heat treatment;
• cold rolling the starting material to produce a workpiece which has an outer diameter and wall thickness for cold drawing to be applied thereto;
• and
• subjecting an inner surface of the workpiece to a pickling treatment with fluoronitric acid to obtain the blank tube before drawing;
• and
• wherein the inner surface roughness of blank tube before drawing when represented by an average surface roughness Ra defined in ANSI B46.1, satisfies formula (i) below,
• 0.10 μm≦Ra≦1.00 μm (i).

A method for producing a cold drawn tube, wherein cold drawing is performed for a heat transfer tube for a steam generator for nuclear power generation the method comprising:

• subjecting a starting material which is produced in a hot working method to a bright heat treatment;
• cold rolling the starting material to produce a workpiece which has an outer diameter and wall thickness for cold drawing to be applied thereto;
• subjecting an inner surface of the workpiece to a blasting treatment by use of blast grains of #200 to #350 in microgrits classification defined in ISO 8486 1996 F standard, the blast grains being made of zirconium oxide, to provide a blank tube for cold drawing in which an inner surface roughness of the blank tube before drawing, when represented by an average surface roughness Ra defined in ANSI B46.1, satisfies formula (ii) below, and
• forming an oil lubricating film on a surface of the workpiece and performing a high-pressure lubrication drawing;
• 0.10 μm≦Ra≦0.50 μm (ii).

A method for producing a blank tube for cold drawing, wherein the blank tube before drawing is provided with an oil lubrication film on a surface thereof and the blank tube is used in a high-pressure lubrication drawing, the method comprising:

• subjecting a starting material which is produced in a hot working method to a bright heat treatment;
• cold rolling the starting material to produce a workpiece which has an outer diameter and wall thickness for cold drawing to be applied thereto;
• and
• subjecting an inner surface of the workpiece to a pickling treatment with fluoronitric acid to obtain the blank tube before drawing,
• wherein the inner surface roughness of the blank tube before drawing, when represented by an average surface roughness Ra defined in ANSI B46.1, satisfies formula (i) or formula (ii) below,
• 0.10 μm≦Ra≦1.00 μm (i), or
• 0.10 μm≦Ra≦0.50 μm (i).

A method for producing a cold drawn tube, wherein cold drawing is performed for a heat transfer tube for a steam generator for nuclear power generation, the method comprising:

• subjecting a starting material which is produced in a hot working method to a bright heat treatment;
• cold rolling the starting material to produce a workpiece which has an outer diameter and wall thickness for cold drawing to be applied thereto;
• and
• subjecting an inner surface of the workpiece to a pickling treatment with fluoronitric acid to obtain the blank tube before drawing I in which an inner surface roughness of blank tube before drawing, when represented by an average surface roughness Ra defined in ANSI B46.1, satisfies formula (i) below,
• forming an oil lubricating film on a surface of the workpiece and performing a high-pressure lubrication drawing;
• 0.10 μm≦Ra≦1.00 μm (i).

A method for producing a blank tube for cold drawing, wherein the blank tube before drawing is provided with an oil lubrication film on a surface thereof and the blank tube is used in a high-pressure lubrication drawing, the method comprising:

• subjecting a starting material which is produced in a hot working method to a bright heat treatment;
• cold rolling the starting material to produce a workpiece which has an outer diameter and wall thickness for cold drawing to be applied thereto;
• and
• subjecting an inner surface of the workpiece to a pickling treatment with fluoronitric acid to obtain the blank tube before drawing,
• wherein the inner surface roughness of the blank tube before drawing
• when represented by an average surface roughness Ra defined in ANSI B46.1, satisfies formula (ii) below,
• 0.10 μm≦Ra≦0.50 μm (ii).