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A high-strength, excellent low-temperature toughness marine steel and its multi-stage heat treatment process for a steel

A low-temperature toughness, marine steel technology, applied in the field of metallurgy, can solve the problems of high alloy cost, different alloy composition schemes, complex production process, etc., and achieve the effects of reducing energy consumption, shortening production cycle, and wide process adaptability

Active Publication Date: 2019-06-04
NANJING IRON & STEEL CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is to solve the problems in the prior art that different strength grades and different thicknesses of marine steel require different alloy composition schemes, high alloy cost and complicated production process, and provide a high-strength, excellent low-temperature toughness marine steel and Its one-steel multi-stage heat treatment process can be used for high-strength, excellent low-temperature toughness marine steel composition scheme and one-steel multi-stage (E460-E550) flexible manufacturing process method

Method used

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  • A high-strength, excellent low-temperature toughness marine steel and its multi-stage heat treatment process for a steel
  • A high-strength, excellent low-temperature toughness marine steel and its multi-stage heat treatment process for a steel
  • A high-strength, excellent low-temperature toughness marine steel and its multi-stage heat treatment process for a steel

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Experimental program
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Effect test

Embodiment 1

[0019] The steel plate thickness of this embodiment is 42mm, and its chemical composition is C 0.13%, Si 0.20%, Mn 1.45%, Ni 0.12%, Cr 0.16%, Mo 0.08%, Nb 0.023%, Ti 0.014%, V≤ 0.02%, P≤0.015%, S≤0.0022%, B 0.002% and the balance Fe.

[0020] Manufacture steel slabs according to the above composition, heat the steel slabs to 1050-1150°C, control rolling to a specified thickness, air-cool to room temperature after rolling, and then conduct heat treatment. Samples are taken on finished marine steel plates, and then tensile and low temperature impact tests are performed.

[0021] The heat treatment process of the test steel is as follows:

[0022] (1) Sub-temperature quenching: Heat the test steel to 820°C, keep it warm for 50min, and then water-cool to room temperature.

[0023] (2) Tempering: Heat the sample that has been quenched and cooled to room temperature to 635°C, keep it warm for 60min, and then take it out and cool it in air.

[0024] After the above treatment, the ...

Embodiment 2

[0026] The thickness of the steel plate in this embodiment is 27 mm, and its chemical composition is the same as that in Embodiment 1.

[0027] The heat treatment process of the test steel is as follows:

[0028] (1) Sub-temperature quenching: Heat the test steel to 790°C, keep it warm for 35min, and then water-cool to room temperature.

[0029] (2) Tempering: Heat the sample that has been quenched and cooled to room temperature to 600°C, keep it warm for 45 minutes, and then take it out and air-cool it.

[0030] After the above treatment, the tempered tissue such as figure 1 As shown, it is ferrite + tempered sorbite, and the volume fraction of ferrite is 32%. The yield strength of the test steel is 521MPa, the tensile strength is 615MPa, the elongation is 22.60%, and the impact energy absorbed at -40°C is 218 / 216 / 215J respectively, which can meet the requirements of E460 strength grade.

Embodiment 3

[0032] The thickness of the steel plate in this embodiment is 50mm, and its chemical composition is C 0.12%, Si 0.24%, Mn 1.56%, Ni 0.14%, Cr 0.23%, Mo 0.09%, Nb 0.025%, Ti 0.012%, V≤ 0.02%, P≤0.015%, S≤0.002%, B 0.0027% and the balance Fe.

[0033] Manufacture steel slabs according to the above composition, heat the steel slabs to 1050-1150°C, control rolling to a specified thickness, air-cool to room temperature after rolling, and then conduct heat treatment. Samples are taken from finished marine steel plates, and then tensile and low-temperature impact tests are performed.

[0034] The heat treatment process of the test steel is as follows:

[0035] (1) Sub-temperature quenching: Heat the test steel to 790°C, keep it warm for 60min, and then water-cool to room temperature.

[0036] (2) Tempering: Heat the sample that has been quenched and cooled to room temperature to 560°C, keep it warm for 90 minutes, and then take it out and air-cool it.

[0037] After the above trea...

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Abstract

The invention is a high-strength, excellent low-temperature toughness marine steel and its multi-stage heat treatment process for a steel. The mass percentages of chemical components are: C0.12‑0.15%, Si0.20‑0.30%, Mn1.40‑1.70%, Ni0. 12‑0.15%, Cr0.16‑0.25%, Mo0.08‑0.12%, Nb0.020‑0.030%, Ti0.012‑0.018%, V≤0.02%, P≤0.015%, S≤0.002%, B0. 0020‑0.0030%, and the balance of Fe and unavoidable impurities. Through the combination of different quenching and tempering processes of the process of the present invention, it is possible to produce a steel plate for ships with a maximum thickness of 50 mm that meets the E460-E550 strength grade, high strength, excellent low-temperature toughness, low alloy cost, and wide process adaptability. The invention solves the problems that different steel grades and plate thicknesses require different components, and the production organization is difficult, and realizes flexible manufacturing of one steel with multiple levels.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and relates to marine steel and its heat treatment process, in particular to a high-strength, excellent low-temperature toughness marine steel and its multi-stage heat treatment process for one steel. Background technique [0002] After entering the 21st century, with the development of science and technology and economic globalization, more and more attention has been paid to the development of marine resources and marine transportation. In the shipbuilding industry, in 2010, China's shipbuilding completions accounted for 41.9% of the world market share, new orders accounted for 48.5% of the world market share, and orders in hand accounted for 40.8% of the world market share, all ranking first in the world. China has already Become the shipbuilding center of the world. The rapid development of the marine engineering equipment manufacturing industry has provided opportunities for the upstream...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C22C38/58C21D1/18C21D6/00
CPCC21D1/18C21D6/004C21D6/005C21D6/008C22C38/02C22C38/04C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C22C38/58C21D1/185
Inventor 谢章龙陈锋王攀峰靳星张丙军王兆华胡其龙
Owner NANJING IRON & STEEL CO LTD
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