Equipment line for manufacturing heavy-walled steel products

Patent metadata

Field	Value
Publication number	US-10562085-B2
Application number	US-201415031247-A
Country	US
Kind code	B2
Filing date	Sep 25, 2014
Priority date	Oct 21, 2013
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

An equipment line for manufacturing heavy-walled steel products having excellent low-temperature toughness, the equipment line including a heating device, a cooling device, and a hot working device in this order. The working device includes plurality of hot working devices, and the cooling device is arranged on an entrance side of at least one of the plurality of hot working devices. Furthermore, a thermostat equipment is arranged on an exit side of the hot working device. The equipment line provides a steel product with a finer microstructure with a relatively small amount of working.

First claim

What is claimed is:

1. A method of manufacturing heavy-walled high-strength steel products using an equipment line comprising:
a heating device,
a hot working device,
a cooling system, which is arranged between the heating device and the hot working device, and
a thermal insulator, which is arranged on an exit side of the hot working device,
the method comprising:
heating a steel in the heating device at a heating temperature within a range from an Ac 4 transformation point to less than a melting point of the steel,
cooling the heated steel in the cooling system such that the heated steel is subjected to cooling at an average cooling rate of 1.0° C./s or above on a surface of the steel until a cooling stop temperature is achieved, the cooling stop temperature being at least 600° C. such that a difference between the cooling stop temperature and a cooling start temperature is 50° C. or more, and
hot working the cooled steel in the hot working device, and further passing the hot worked steel through the thermal insulator such that a cooling rate of the heavy-walled steel product after the hot working is slowed down to an average cooling rate of 20° C./s or less, so that the hot worked steel has a predetermined size,
wherein the steel has a chemical composition comprising:
0.050% or less C, by mass %,
0.50% or less Si, by mass %,
0.20 to 1.80% Mn, by mass %,
15.5 to 18.0% Cr, by mass %,
1.5 to 5.0% Ni, by mass %,
3.5% or less Mo, by mass %,
0.02 to 0.20% V, by mass %,
0.01 to 0.15% N, by mass %,
0.006% or less O, by mass %, and
Fe and unavoidable impurities.

2. The method of manufacturing heavy-walled high-strength stainless steel products according to claim 1 , wherein the chemical composition further comprises at least one group selected from the following element groups A to D:
Group A: 0.002 to 0.050% Al, by mass %,
Group B: 3.5% or less Cu, by mass %,
Group C: at least one element selected from 0.2% or less Nb, 0.3% or less Ti, 0.2% or less Zr, 3.0% or less W, and 0.01% or less B, by mass %, and
Group D: at least one element selected from 0.01% or less Ca, and 0.01% or less REM, by mass %.

Assignees

• Jfe Steel Corp

Inventors

• Sasaki Shunsuke
• Katsumura Tatsuro
• Kato Yasushi

Classifications

• B21B45/02

  for lubricating, cooling, or cleaning {(in particular in combination with forging or pressing devices B21B15/005, control of flatness or profile using lubricating or cooling B21B37/44)} · CPC title

• B21B45/00

  Devices for surface {or other} treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills (B21B15/00, {B21B1/227 and B21B27/005} take precedence; technical features of scaling-off devices B21C43/00) · CPC title

• C22C38/58

  with more than 1.5% by weight of manganese · CPC title

• B21B19/04 Primary

  Rolling basic material of solid, i.e. non-hollow, structure; Piercing {, e.g. rotary piercing mills} · CPC title

• B21B23/00

  Tube-rolling not restricted to methods provided for in only one of groups B21B17/00, B21B19/00, B21B21/00, e.g. combined processes {planetary tube rolling, auxiliary arrangements, e.g. lubricating, special tube blanks, continuous casting combined with tube rolling}(B21B25/00 takes precedence) · CPC title