Production method of seamless tube using round bar made of high Cr-high Ni alloy

Patent metadata

Field	Value
Publication number	US-9468959-B2
Application number	US-201113996157-A
Country	US
Kind code	B2
Filing date	Dec 20, 2011
Priority date	Dec 22, 2010
Publication date	Oct 18, 2016
Grant date	Oct 18, 2016

Abstract

A continuously cast slab with a rectangular cross section, and made of high alloy containing Cr of 20 to 30 mass %, Ni of 30 to 50 mass %, and at least one of Mo and W as Mo+0.5W of 1.5 mass % or more is subjected to blooming and billet-making to yield a round bar having a diameter of 150 to 400 mm as a starting material of the seamless tube. The blooming and billet-making process is performed under a condition satisfying a relation of 1.3≦H/D≦1.8 where a short side length of the cross section of the cast slab is defined as H (mm), and the diameter of the round bar is defined as D (mm). The round bar is pierced-rolled to make a hollow blank; the hollow blank tube is elongation-rolled, and then diameter-adjusting-rolled to make the seamless tube, thereby preventing end cracking during piercing-rolling, and increasing yield.

First claim

What is claimed is:

1. A production method of a seamless tube with a Mannesmann tube-making process comprising:
subjecting a continuously cast slab with a rectangular cross section, and made of high Cr-high Ni alloy containing Cr of 20 to 30 mass %, Ni of 30 to 50 mass %, and at least one of Mo and W as Mo+0.5W of 1.5 to 10 mass % to a blooming and billet-making process to yield a round bar having a diameter of 150 to 400 mm;
subjecting the round bar to a piercing-rolling process through a piercing mill to yield a hollow blank; and
subjecting the hollow blank to an elongation-rolling process through an elongation-rolling mill; followed by a diameter-adjusting-rolling process through a diameter-adjusting-rolling mill;
wherein the blooming and billet-making process is carried out under a condition satisfying a relation of 1.3≦H/D≦1.8 where a short side length of the cross section of the cast slab is defined as H (mm), and the diameter of the round bar is defined as D (mm).

2. A production method of a round bar for a seamless tube comprising:
subjecting a continuously cast slab with a rectangular cross section, and made of high Cr-high Ni alloy containing Cr of 20 to 30 mass %, Ni of 30 to 50 mass %, and at least one of Mo and W as Mo+0.5W of 1.5 to 10 mass % to a blooming and billet-making process to yield a round bar having a diameter of 150 to 400 mm as a starting material of the seamless tube,
wherein the blooming and billet-making process is carried out under a condition satisfying a relation of 1.3≦/D≦1.8 where a short side length of the cross section of the cast slab is defined as H (mm), and the diameter of the round bar is defined as D (mm).

Assignees

• Hirase Naoya
• Satou Takanori
• Nippon Steel & Sumitomo Metal Corp

Inventors

• Hirase Naoya
• Satou Takanori

Classifications

• Y10T29/49991

  Combined with rolling · CPC title

• C21D9/0075

  for rods of limited length (of unlimited length C21D9/52) · CPC title

• B21B2001/022

  Blooms or billets · CPC title

• B21B1/026 Primary

  Rolling · CPC title

• C22C30/00

  Alloys containing less than 50% by weight of each constituent · CPC title