# US 2020/0399728 A1 · Continuous hot rolled coil for high collapse-resistant sew petroleum casing and manufacturing method thereof

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- Number: US 2020/0399728 A1
- Document ID: US20200399728A1
- Status: Published application
- Kind: A1
- Application number: 16/614,603
- Filed: 2018-06-20
- Published: 2020-12-24
- Earliest claimed: 2017-09-11
- Assignees: Pangang Group Panzhihua Iraon & Steel Research Institute Co., Ltd
- Applicants: Pangang Group Panzhihua Iraon & Steel Research Institute Co., Ltd
- Inventors: Kaihua ZHANG; Xiaoyu YE; Xuegang XIONG; Yi WANG
- Web page: https://patentgrep.com/patent/US20200399728A1

## CPC

- C21D 8/02: during manufacturing of plates or strips (C21D8/12 takes precedence)
- C21D 9/0068: {for particular articles not mentioned below}
- C21D 6/002: {containing Cr (C21D6/004 takes precedence)}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 8/00: Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02)
- C21D 8/0226: {Hot rolling}
- C21D 9/46: for sheet metals
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/28: with titanium or zirconium
- C21D 9/08: for tubular bodies or pipes
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

The invention discloses a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing and a manufacturing method thereof, and belongs to the technical field of hot continuous rolling production. Provided is a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing with low alloy element cost and excellent initial welding property, and a manufacturing method thereof. The production cost of the hot continuous rolled coil is lowered by reducing expensive alloy elements such as Mo and V therein, and strictly controlling the content components of chemical elements such as Cr, Mn and Ti. According to the manufacturing method, a continuous cast slab is used as an initial billet and subjected to rough rolling by refined grains for 5-7 passes under the temperature-controlled heating condition to form an intermediate billet, and then the intermediate billet is subjected to finish rolling for at least 4 passes, then finally cooled and coiled to complete the production and processing of the continuous hot rolled coils, and achieve the purpose of controlling the initial yield strength and the initial tensile strength.

## Claims

### Claim at position 1

1-2. (canceled)

### Claim 3

A method of manufacturing a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing, said method comprising:
providing a continuous cast slab for use as an initial billet;
subjecting the continuous cast slab to rough rolling by refined grains for 5-7 passes under a temperature-controlled heating condition to form an intermediate billet;
subjecting the intermediate billet to finish rolling for at least 4 passes, and
cooling and coiling the intermediate billet after the finish rolling to provide the continuos hot rolled coil,
wherein;
a deformation of the initial billet must be not less than 18% in each pass where the initial billet is subjected to the rough rolling by the refined grains;
the intermediate billet subjected to the finish rolling is 3.8-4.2 times thicker than the continuous hot rolled coil;
the cooling of the intermediate billet before coiling is air cooling;
the continuous hot rolled coil comprises the following chemical components in parts by weight: 0.22-0.32% of C, 0.10-0.30% of Si, 1.10-1.40% of Mn, 0.30-0.60% of Cr, ≤0.020% of P, ≤0.010% of S, 0.008-0.019% of Ti, Fe and inevitable impurities;
an initial yield strength of the continuous hot rolled coil is 340-360 MPa;
an initial tensile strength of the continuous hot rolled coil is 620-640 MPa;
a yield strength of the continuous hot rolled coil after quenching and tempering is 840 Mpa-910 MPa; and
a tensile strength of the continuous hot rolled coil after quenching and tempering is 940-1030 MPa.

### Claim 4 (depends on 3)

The method according to claim 3, wherein a heating temperature is kept at 1180-1220° C. during each pass of the rough rolling.

### Claim 5 (depends on 3)

The method according to claim 3, wherein an initial thickness of the continuous cast slab is 200-250 mm.

### Claim 6 (depends on 3)

The method according to claim 3, wherein each pass of the finish rolling is completed at once by a finishing mill unit.

### Claim 7 (depends on 6)

The method according to claim 6, wherein an inlet temperature is kept at 970-1020° C. during the finish rolling and a finish rolling temperature is 850-900° C.

### Claim 8 (depends on 3)

The method according to claim 3, wherein the continuous cast slab subjected to the rough rolling enters a hot coil box for coiling a head and a tail thereof alternately, and then is uncoiled for temperature control and finish rolling in a finish rolling area.

### Claim 9 (depends on 3)

The method according to claim 3, wherein the chemical compositions are 0.24-0.30% of C, 0.10-0.30% of Si, 1.20-1.40% of Mn, 0.40-0.50% of Cr, ≤0.018% of P, ≤0.005% of S, 0.010-0.017% of Ti, Fe and inevitable impurities.

### Claim 10 (depends on 9)

The method according to claim 9, wherein a heating temperature is kept at 1180-1220° C. during each pass of the rough rolling.

### Claim 11 (depends on 9)

The method according to claim 9, wherein an initial thickness of the continuous cast slab is 200-250 mm.

### Claim 12 (depends on 9)

The method according to claim 9, wherein each pass of the finish rolling is completed at once by a finishing mill unit.

### Claim 13 (depends on 12)

The method according to claim 12, wherein an inlet temperature is kept at 970-1020° C. during the finish rolling and a finish rolling temperature is 850-900° C.

### Claim 14 (depends on 9)

The method according to claim 9, wherein the continuous cast slab subjected to the rough rolling enters a hot coil box for coiling a head and a tail thereof alternately, and then is uncoiled for temperature control and finish rolling in a finish rolling area.