A kind of low pcm value large thickness easy-to-weld marine steel plate and production method thereof

A large-thickness, easy-to-weld technology, applied in the field of medium-thick steel plate preparation, can solve the problems of thickness specification limitation, long process, high energy consumption, etc., and achieve the effect of improving fracture toughness, stability, and expansion work.

Active Publication Date: 2021-05-25
SD STEEL RIZHAO CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] To sum up, subject to the actual conditions of the size specifications that domestic continuous casting slabs can supply (basically 250-300mm), and under the premise of insufficient hardenability due to low crack sensitivity coefficient, if large-thickness steel plates want to use large-thickness slabs for production, it can The thickness specifications of the supply are limited; if the heat treatment process is used to produce, there are practical problems such as long process, need for supporting special equipment, and large energy consumption. Therefore, it is urgent to develop an easy-to-weld high-strength and tough marine steel with large thickness and low Pcm Process production method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] The chemical composition includes (by weight%): C: 0.04%, Si: 0.28%, Mn: 1.37%, Nb: 0.036%, V: 0.032%, Ti 0.018%, Ni: 0.22%, Mo: 0.15%, Al: 0.021%, P: 0.012%, S: 0.003%, Pcm: 0.13%, and the rest is Fe and unavoidable impurities. The cast slab was reheated to around 1155°C for 260 minutes in the furnace. After being released from the furnace, it enters the rough rolling mill for rolling in the high temperature zone. The rolling starts at 1090°C, and the rolling at this stage ends at 1025°C. ℃. The water cooling temperature after rolling is controlled at 770°C, and cooled to 460°C at a rapid cooling rate of 24°C / s. Then leave the water-cooling zone and cool naturally to room temperature to make steel plates. The tensile strength of the steel plate is 640MPa, CTOD (-10°C) = 1.06, 0.87, 1.25mm, the preheating temperature calculated according to the oblique Y-shaped groove restraint formula is -72°C, and it can be welded at room temperature without cold cracks .

Embodiment 2

[0030]The chemical composition includes (by weight%): C: 0.06%, Si: 0.15%, Mn: 1.54%, Nb: 0.043%, V: 0.041%, Ti 0.013%, Ni: 0.30%, Mo: 0.27%, Al: 0.033%, P: 0.010%, S: 0.002%, Pcm: 0.17%, and the rest is Fe and unavoidable impurities. The cast slab was reheated to around 1193°C for 300 minutes in the furnace. After coming out of the furnace, it enters the rough rolling mill for rolling in the high temperature zone. The rolling starts at 1115°C. The total rolling passes at this stage are 7 passes, of which the 4th, 5th, and 6th passes are respectively reduced by 40, 42, and 42mm. The rolling speed is controlled at less than 1.5m / s; the steel billet is cooled to 800°C on the roller table and sent to the finishing mill to be rolled into a finished steel plate with a thickness of 80mm, and the final rolling temperature is 790°C. After rolling, the inlet water cooling temperature was detected as 755°C, and cooled to 330°C at a cooling rate of 12°C / s. Then leave the water-cooling ...

Embodiment 3

[0032] The chemical composition includes (by weight%): C: 0.03%, Si: 0.10%, Mn: 1.60%, Nb: 0.050%, V: 0.030%, Ti 0.020%, Ni: 0.35%, Mo: 0.10%, Al: 0.0151%, P: 0.013%, S: 0.003%, Pcm: 0.12%, and the rest is Fe and unavoidable impurities. The cast slab was reheated to around 1140°C for 280 minutes in the furnace. After coming out of the furnace, it enters the rough rolling mill for high-temperature rolling, and starts rolling at 1000°C. There are 7 total rolling passes in this stage, of which the 4th, 5th, and 6th passes are respectively reduced by 40, 42, and 42mm, and the rolling speed is controlled at less than 2.0m / s; the steel billet is cooled to 810°C on the roller table and sent to the finishing mill to be rolled into a finished steel plate with a thickness of 80mm, and the final rolling temperature is 800°C. After rolling, the inlet water cooling temperature was detected as 765°C, and cooled to 300°C at a cooling rate of 15°C / s. Then leave the water-cooling zone and co...

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Abstract

The invention relates to an easily weldable marine steel plate with a thickness of 80mm when the Pcm value is 0.18%, and a production method thereof. The chemical composition weight percentage is: C: 0.03%-0.06%, Si: 0.10%-0.30%, Mn: 1.30%~1.60%, P≤0.015%, S≤0.005%, Al: 0.015%~0.035%, Nb: 0.030%~0.050%, V: 0.030%~0.050%, Ti: 0.010%~0.020%, Ni: 0.15% to 0.35%, Mo: 0.10% to 0.30%, Pcm: 0.12% to 0.18%, and the rest are Fe and unavoidable impurities. The steel plate of the invention has high strength plasticity, high crack arrestability and easy weldability, and can meet the requirements of low preheating temperature for high-performance steel in harsh environments such as marine engineering, bridges, and oil pipelines.

Description

technical field [0001] The invention belongs to the field of medium-thick steel plate preparation, and in particular relates to a low-Pcm value large-thickness easy-to-weld marine steel plate and a production method thereof. Background technique [0002] With the development of the user industry, there is a strong demand for large-thickness steel plates in marine engineering, bridges, oil pipelines and other fields, especially offshore platforms and large container ships mainly use steel plates with a thickness of 10-130mm, and the thickness of steel for jacket platforms is generally 60-80mm , The welding process accounts for 40% of the total construction time and 50% of the total cost. [0003] Welding cold cracks are the most common welding process defects in steel structural parts, which are extremely harmful to structural safety. The traditional technological measure to prevent welding cold cracks is preheating. As the strength level increases, the carbon equivalent (C...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14C22C38/08C21D8/02
CPCC21D8/0226C21D2211/002C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/14
Inventor 胡淑娥周兰聚侯东华李宝伟韩启彪杨建勋成小龙李博
Owner SD STEEL RIZHAO CO LTD
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