Low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships and production method thereof

A technology of LT-FH40 and production method, applied in the field of iron and steel, can solve the problems of complex rolling process, difficult to meet the requirements of thickness and performance, increase cost, etc., and achieve the effect of reducing production cost

Inactive Publication Date: 2015-12-02
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, due to the strict control of low-temperature steel composition requirements, the smelting and rolling processes are very complicated, and it is difficult to meet the required thickness and p

Method used

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  • Low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships and production method thereof
  • Low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships and production method thereof
  • Low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships and production method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] This embodiment provides a hot-rolled marine low-temperature ferritic LT-FH40 steel plate, which contains the components in the following table (1), and the remaining content is Fe and unavoidable impurities.

[0022] (1) Chemical composition (%)

[0023] steel type

C

mn

Si

P

S

Nb

Alt

Ti

Ni

Ceq

LT-FH40

0.04

1.35

0.10

0.006

0.003

0.010

0.02

0.007

0.25

0.29

[0024] The refinement of austenite grains can be controlled by the second phase precipitates, which are usually achieved by adding alloying elements such as Nb and Ti, which can form carbon, nitrogen or carbonitride precipitation during the cooling process of the steel. During the austenitization process of steel, the grain boundaries are pinned, thereby inhibiting the growth of austenite grains. Controlling the niobium-titanium content within a certain range not only does not have a harmful effect on the strength ...

Embodiment 2

[0034] Present embodiment LT-FH40 steel plate comprises following table (1-1) component

[0035] (1-1) Chemical composition (%)

[0036] steel type

Embodiment 3

[0038] Present embodiment LT-FH40 steel plate comprises following table (1-2) component

[0039] (1-3) Chemical composition (%)

[0040] steel type

[0041] Compared with Example 1, Examples 2 and 3 have different chemical composition ratios; however, the production process is basically the same, so details are not repeated here. Through the composition design of low-carbon and niobium-titanium alloying, the schematic diagram of the metallographic structure of the obtained steel plate is as follows Figure 1-3 shown. Using two-stage controlled rolling technology in the austenite recrystallization zone and austenite non-recrystallization zone, the rough rolling single-pass reduction rate is greater than 15% to break the austenite grains, and the rough rolling finish rolling temperature is controlled at 1000°C; The starting temperature of finish rolling is controlled to be ≤840°C, and the cumulative reduction rate of the last three passes of finish rolling is greater...

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PUM

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Abstract

The invention relates to a low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships. The steel plate comprises the following chemical components in percentage by mass: 0.04-0.09% of C, 0.10-0.30% of Si, 1.35-1.55% of Mn, smaller than or equal to 0.008% of P, smaller than or equal to 0.004% of S, 0.20-0.45% of Ni, 0.010-0.035% of Nb, 0.007-0.020% of Ti, 0.020-0.050% of Alt and the balance being Fe and inevitable impurities. Through cooperation of low-carbon and niobium-titanium alloying composition design, a low-phosphorus and low-sulfur smelting process and a reasonable controlled rolling and cooling process, the low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships is produced; the hot-rolled state mechanical performance meets the standard requirements. The requirement of low-temperature vessel steel applied to ships is successfully solvedmet by the method; the low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships can be produced by processes such as converter steelmaking and continuous casting and can be produced by a large number of steel enterprises; the low-temperature ferrite LT-FH40 steel plate applied to hot-rolled ships is produced by a TMCP process, so that the production cost is reduced.

Description

technical field [0001] The invention relates to a low-temperature ferrite LT-FH40 steel plate for ships in a hot-rolled state and a production method thereof, belonging to the technical field of iron and steel. Background technique [0002] Low-temperature steel should mainly have the following properties: toughness and brittleness transition temperature lower than the use temperature; stable structure at the use temperature; good weldability and formability; some special purposes also require extremely low magnetic permeability, cold shrinkage etc. In particular, the characteristics of marine low-temperature steel plates determine that they must have high strength, high toughness, fatigue resistance, lamellar tear resistance, good weldability, and seawater corrosion resistance. At present, due to the strict control of low-temperature steel composition requirements, the smelting and rolling processes are very complicated, and it is difficult to meet the required thickness a...

Claims

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Application Information

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IPC IPC(8): C22C38/14C22C33/04C21D8/02
Inventor 汪五一楚觉非柳东徽刘勇陈飞
Owner NANJING IRON & STEEL CO LTD
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