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New process for producing low-alloy structural steel by adding ferro-vanadium-nitride

A ferrovanadium nitride and low-alloy technology, applied in the field of new production process of low-alloy structural steel, can solve the problems of reduced toughness, unqualified strength, banded structure, etc., and achieve the effect of reducing the amount of addition and reducing the cost per ton of steel

Inactive Publication Date: 2013-09-25
SHANDONG TAISHAN STEEL GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Q345B is a low-alloy steel with a C content of less than 0.20%. Due to its good comprehensive performance, it is widely used in ships, bridges, vehicles, construction and other fields. However, during the production process, the product is prone to unqualified strength and abnormal structure. Phenomena such as bainite and banded structure affect the mechanical properties and service requirements of the product
[0003] Conventional Q345B steel usually adds 1.0% to 1.7% Mn element in the steel to ensure the strength of the product. Manganese mainly plays a solid solution strengthening role in the steel. Recent studies have shown that when W(Mn)<2.0%, the steel The strength of the steel plate increases with the increase of manganese content, while the trend of impact toughness decline is very small, and does not affect its brittle transition temperature. However, if the manganese content is too high, it will cause serious banded structure, toughness reduction and anisotropy of the steel plate.

Method used

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  • New process for producing low-alloy structural steel by adding ferro-vanadium-nitride
  • New process for producing low-alloy structural steel by adding ferro-vanadium-nitride

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] (1) Converter smelting: The chemical composition is controlled as follows: C: 0.13%, Si: 0.12%, Mn: 0.75%, P: 0.019%, S: 0.007%, V: 0.028%, Fe balance;

[0016] (2) LF refining: before refining, the temperature is 1589℃, the free oxygen is 25ppm, and the thickness of the slag layer is 35mm; after refining, the oxygen content is 11ppm, R: 3.5, FeO: 0.6%; after refining, the calcium treatment is 2.7 m / ton of steel;

[0017] (3) Continuous casting: 150*770 section, pulling speed 1.05±0.05m / min;

[0018] (4) Hot rolling: the temperature in the soaking section of the heating furnace is 1260 °C, and the slab is cold loaded in the furnace for 100 minutes; the rough rolling temperature is 1190 °C, the finishing rolling temperature is 880 °C, and the coiling temperature is 660 °C. The cooling method adopts Front section cooling (only the first four groups of cooling water are turned on).

Embodiment 2

[0020] (1) Converter smelting: The chemical composition is controlled as follows: C: 0.15%, Si: 0.16%, Mn: 0.70%, P: 0.020%, S: 0.009%, V: 0.025%, Fe balance;

[0021] (2) LF refining: Before refining, the temperature is 1585℃, the free oxygen is 20ppm, and the thickness of the slag layer is 40mm; after refining, the oxygen content is 10ppm, R: 3.8, FeO: 0.7%; after refining, the calcium treatment is 2.9 m / ton of steel;

[0022] (3) Continuous casting: 150*770 section, pulling speed 1.05±0.05m / min;

[0023] (4) Hot rolling: the temperature in the soaking section of the heating furnace is 1270 °C, the slab is cold loaded in the furnace for 110 minutes, the rough rolling temperature is 1185 °C, the finishing rolling temperature is 872 °C, and the coiling temperature is 665 °C. The cooling method adopts Front section cooling (only the first four groups of cooling water are turned on).

Embodiment 3

[0025] (1) Converter smelting: The chemical composition is controlled as follows: C: 0.14%, Si: 0.15%, Mn: 0.68%, P: 0.018%, S: 0.008%, V: 0.026%, Fe balance;

[0026] (2) LF refining: Before refining, the temperature is 1583℃, the free oxygen is 27ppm, and the thickness of the slag layer is 41mm; after refining, the oxygen content is 16ppm, R: 4.1, FeO: 0.8%, and the calcium treatment after refining is 2.5 m / ton of steel;

[0027] (3) Continuous casting: section 150*810, pulling speed 1.00±0.05 m / min;

[0028] (4) Hot rolling: the temperature in the soaking section of the heating furnace is 1270 °C, and the slab is hot charged in the furnace for 90 minutes; the rough rolling temperature is 1183 °C, the finishing rolling temperature is 869 °C, and the coiling temperature is 668 °C. The cooling method adopts Front section cooling (only the first four groups of cooling water are turned on).

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Abstract

The invention discloses a new process for producing low-alloy structural steel by adding ferro-vanadium-nitride. The new process comprises the following steps: (1) smelting in a converter; (2) refining in a ladle furnace; (3) performing continuous casting; (4) performing hot rolling. Compared with the prior art, the new process has the following advantages: 1, a Q345B hot-rolled steel strip chemical composition system is designed innovatively, and a reasonable composition control technology is realized; the content of element Mn is reduced by 0.45 percent at least; meanwhile 0.015 to 0.030 percent of the element V is added, so that the cost of the steel per ton is further reduced; 2, the conventional high-manganese alloying is replaced by ferro-vanadium-nitride micro-alloying, the adding amount of alloying elements is reduced; the reducing production is realized, and meanwhile refined crystalline strengthening and precipitation strengthening are played better.

Description

technical field [0001] The invention relates to a new process for producing low-alloy structural steel, in particular to a process for producing Q345B hot-rolled sheet by adding ferrovanadium nitride, optimizing the chemical composition of steel grades, adopting a controlled rolling and controlled cooling process, and optimizing product structure. new technology. Background technique [0002] Q345B is a low-alloy steel with a C content of less than 0.20%. Due to its good comprehensive properties, it is widely used in ships, bridges, vehicles, construction and other fields. However, in the production process, the product is prone to unqualified strength and abnormal structure. Bainite, banded structure and other phenomena affect the mechanical properties and application requirements of the product. [0003] Conventional Q345B steel is usually added with 1.0% to 1.7% Mn element in the steel to ensure the strength of the product. Manganese mainly plays the role of solid soluti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/12C22C33/04C21D8/02
Inventor 马正伟谷国刚谷国华赵丽明张振会
Owner SHANDONG TAISHAN STEEL GROUP
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