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Ultra-fine-grain ultra-thick steel with yield strength of not less than 480MPa grade, and preparation method

A yield strength, ultra-fine grain technology, applied in the field of metallurgy, can solve the problems of high Ni content of precious metals, high production costs, low Kca value, etc., and achieve the effect of uniform distribution, hindering generation and propagation, and fine grains

Active Publication Date: 2018-05-25
SD STEEL RIZHAO CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] CN104264047A discloses a kind of extra-thick steel plate for container ships and its preparation method, which is mainly composed of acicular ferrite, without forming ultra-fine grain layer, and the Kca value is low; in addition, the precious metal Ni content is high, and the production cost is high

Method used

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  • Ultra-fine-grain ultra-thick steel with yield strength of not less than 480MPa grade, and preparation method
  • Ultra-fine-grain ultra-thick steel with yield strength of not less than 480MPa grade, and preparation method
  • Ultra-fine-grain ultra-thick steel with yield strength of not less than 480MPa grade, and preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] The chemical composition of the 60mm ultra-fine-grained extra-thick steel in this example is as follows: C: 0.08%, Si: 0.25%, Mn: 1.60%, P: 0.015%, S: 0.003%, Al: 0.01%, Cr: 0.22% , Mo: 0.25%, Nb: 0.03%, V: 0.04%, Ti: 0.018%, the rest is Fe and unavoidable impurities, of which H≤0.0003%.

[0030] The slab is slowly cooled to below 300°C, the thickness of the slab is 300mm, and a three-stage heating process is adopted. The first stage: the temperature in the preheating section is set at 700-850°C; the second stage: it is divided into heating 2-1 section and heating 2- 2 sections, heating 2-1 section temperature setting 1050-1200 ℃, heating 2-2 section temperature setting 1180-1230 ℃; third section: furnace gas temperature setting of 1150-1200 ℃ in the soaking section; heat storage Type heating furnace to 1150℃ for tapping.

[0031] Rolling: The slab comes out of the furnace and is water-cooled in multiple channels by the descaling machine to the surface temperature of t...

Embodiment 2

[0034] The chemical composition of the 75mm ultra-fine-grained extra-thick steel in this example is as follows: C: 0.11%, Si: 0.10%, Mn: 1.20%, P: 0.010%, S: 0.002%, Al: 0.03%, Cr: 0.10% , Mo: 0.18%, Nb: 0.04%, V: 0.06%, Ti: 0.025%, the rest is Fe and unavoidable impurities, of which H≤0.0003%.

[0035] The slab is slowly cooled to below 300°C, the thickness of the slab is 300mm, and a three-stage heating process is adopted. The first stage: the temperature in the preheating section is set at 700-850°C; the second stage: it is divided into heating 2-1 section and heating 2- 2 sections, heating 2-1 section temperature setting 1050-1200 ℃, heating 2-2 section temperature setting 1180-1230 ℃; third section: furnace gas temperature setting of 1150-1200 ℃ in the soaking section; heat storage Type heating furnace to 1160℃ for tapping.

[0036] Rolling: The slab comes out of the furnace and is water-cooled in multiple channels by the descaling machine to the surface temperature of t...

Embodiment 3

[0039] The chemical composition of the 90mm ultra-fine-grained extra-thick steel in this example is as follows: C: 0.07%, Si: 0.40%, Mn: 1.80%, P: 0.008%, S: 0.005%, Al: 0.05%, Cr: 0.30% , Mo: 0.10%, Nb: 0.015%, V: 0.08%, Ti: 0.010%, the rest is Fe and unavoidable impurities, of which H≤0.0003%.

[0040] The slab is slowly cooled to below 300°C, the thickness of the slab is 300mm, and a three-stage heating process is adopted. The first stage: the temperature in the preheating section is set at 700-850°C; the second stage: it is divided into heating 2-1 section and heating 2- 2 sections, heating 2-1 section temperature setting 1050-1200 ℃, heating 2-2 section temperature setting 1180-1230 ℃; third section: furnace gas temperature setting of 1150-1200 ℃ in the soaking section; heat storage Type heating furnace to 1180℃ for tapping.

[0041] Rolling: The slab comes out of the furnace and is water-cooled in multiple channels by the descaling machine to the surface temperature of th...

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Abstract

The invention provides ultra-fine-grain ultra-thick steel with a yield strength of not less than 480MPa grade, and a preparation method thereof. The ultra-fine-grain ultra-thick steel is mainly used in the field of large ship manufacturing, and comprises the following chemical components: C, Si, Mn, P, S, Al, Cr, Mo, Nb, V, Ti, Fe and inevitable impurities. The production process flow of the steelcomprises the following steps: molten iron pretreatment, BOF steelmaking, LF refining, RH vacuum treatment, continuous casting, slow cooling, heating, rolling and water cooling, wherein product structures are fine and uniform, and are mainly acicular / polygonal ferrites, granular bainites and an extremely small amount of pearlites. The steel provided by the invention is low in production cost, simple in process, and applicable to large-scale industrial stable production; and the product is excellent in welding performance, lamellar tearing resistance, brittle failure resistance and low-temperature toughness.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to an ultra-fine-grained extra-thick steel with a yield strength not less than 480 MPa and a preparation method thereof. Background technique [0002] With the development of large-scale ships, the steel plates for shipbuilding are also developing in the direction of high strength and extra thickness. Especially for container ships, due to the large-scale deterioration of the stress state of the hull structure, the hatch coaming top plate, web plate, upper deck side plate, sheer strake and some local areas in the hull structure are at a relatively high stress level. Therefore, the hull structure is required to have high strength and rigidity. High-strength steel reduces the safety margin of the structure, and the increase in plate thickness increases the probability of initial defects in the weld; more importantly, it changes the component from a plane stress state t...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/22C22C38/24C22C38/26C22C38/28C22C38/38C22C33/00
CPCC22C33/00C22C38/02C22C38/04C22C38/06C22C38/22C22C38/24C22C38/26C22C38/28C22C38/38
Inventor 李灿明胡淑娥成小龙韩启彪侯东华杨建勋孙京波刘熙章孔雅胡晓英李率民
Owner SD STEEL RIZHAO CO LTD
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