Microalloy HRB500E steel bar containing chrome and nitrogen and production method thereof

A technology of micro-alloying and production method, applied in the field of HRB500E steel bar and its production process, can solve the problems of high welding performance, aging phenomenon, and large fluctuation of steel performance, and achieve good welding performance, stable quality and good anti-corrosion characteristics. Effect

Active Publication Date: 2013-07-17
长沙东鑫环保材料有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method has the following problems: ① high silicon-manganese and carbon content, high carbon equivalent, poor welding performance, and high alloy cost; ② element segregation is easy to occur during solidification and cooling; ③ high vanadium or niobium content, On the one hand, a large amount of precious resources are consumed, and on the other hand, the cost of the alloy is high; ④ Yield is not obvious and mixed crystals are prone to occur
The disadvantages of this method are: ①It is necessary to greatly increase the capacity of the rolling mill or to build a new rolling production line, which requires a huge investment, and the existing equipment cannot be used; The strength is greatly reduced; ③The production of HRB500 by this method is still in the stage of industrial exploration and experimentation, the technology is immature, there are many uncontrollable factors, and the product quality is unstable
The third category is to control the composition to the lower limit, and rarely use vanadium or niobium, and the composition of the alloy can be greatly reduced by forced cooling through water after rolling. This method is only in the stage of industrial testing, and has the following obvious defects: ① Need Increase water-piercing equipment and increase investment; ②The performance of steel bars fluctuates greatly, the aging phenomenon is serious, and the stability of product quality is extremely poor; The HRB500 steel bar produced by this method is not accepted; ④The surface and core structure of the steel bar are inconsistent, and the surface is prone to tempered martensite and tempered sorbite, which exceeds the basic requirements of the national standard that the steel bar structure is ferrite + pearlite

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Add blast furnace molten iron, steel scrap or pig iron into the converter respectively, blow oxygen for smelting, and add slagging materials such as lime, and add reducing chromium oxide pellets and reducing manganese oxide pellets during 7 minutes of oxygen blowing smelting in the converter Mixture, top blowing oxygen for 3 minutes, and bottom blowing for 3 minutes at the same time, so that [C]=0.08-0.120% of molten steel at the end of smelting, [Mn] between 0.12-0.20%, and [Gr] between 0.65-0.750%;

[0039] Add reducing vanadium oxide pellets within 4 minutes before tapping the converter; blow oxygen for 4 minutes, and blow air for 4 minutes at the same time, so that the [V] in the molten steel is between 0.02-0.04%, and the content of other components such as molten steel sulfur is less than 0.035%. The phosphorus content is less than 0.035%, which meets the standard requirements, and the steel is tapped under the condition that the temperature meets the requirements ...

Embodiment 2

[0045] Add blast furnace molten iron, steel scrap or pig iron into the converter respectively, blow oxygen for smelting, and add slagging materials such as lime, and add the mixture of reduced chromium oxide pellets and reduced manganese oxide pellets during oxygen blowing smelting in the converter for 3 minutes ;Blow oxygen at the top for 7 minutes, and blow at the bottom for 7 minutes at the same time, so that the [C] of molten steel at the end of smelting is between 0.06-0.10%, [Mn] is between 0.30-0.40%, and [Gr] is between 0.30-0.40%;

[0046] Add reduced vanadium oxide pellets and reduced niobium oxide pellets within 8 minutes before the converter is tapped; blow oxygen for 8 minutes and bottom blow for 8 minutes at the same time, so that [V]+[Nb] in molten steel is between 0.035-0.050% , other components meet the standard requirements for tapping;

[0047] The steel is tapped under the condition that the sulfur content of the converter molten steel is less than 0.035%, ...

Embodiment 3

[0053] Add blast furnace molten iron, steel scrap or pig iron into the converter respectively, blow oxygen for smelting, and add slagging materials such as lime, and add reduced chromium oxide pellets and reduced manganese oxide pellets during the oxygen blowing smelting in the converter for 10 minutes Mixture, top blowing oxygen for 5 minutes, and bottom blowing for 5 minutes at the same time, so that [C]=0.10-0.15% in molten steel at the end of smelting, [Mn] is between 0.20-0.30%, and [Gr] is between 0.45-0.65%;

[0054] Add reducing niobium oxide pellets within 6 minutes before tapping the converter; blow oxygen for 6 minutes, and at the same time blow bottom gas for 6 minutes, so that [Nb] in molten steel is between 0.05-0.07%, and other components such as molten steel sulfur are less than 0.035%. The phosphorus content is less than 0.035%, which meets the standard requirements, and the steel is tapped under the condition that the temperature meets the requirements of the ...

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Abstract

The invention discloses a microalloy HRB500E steel bar containing chrome and nitrogen and a production method thereof. By fully utilizing the strengthening effect and the corrosion-proof effect of chrome on the steel bar, solid solution strengthening elements, namely manganese and silicon, are partially substituted, and a microalloy element, namely vanadium or columbium is partially or fully substituted; a cheap nitrogen element is used for performing microalloy treatment on the steel bar, so that the micro nitrogen separating strengthening effect is achieved; by the production method, the HRB500E steel bar can be produced; Rel of the steel bar is 520 to 580MPa, Rm of the steel bar is 640 to 730 MPa, A is 22 to 32 percent, Rm / Rel is 1.30 to 1.40, the cold bending qualified rate is 100 percent, the welding carbon equivalent weight is less than or equal to 0.50, and the comprehensive cost of one ton of steel bar is 40-100 yuan lower than that of one ton of the steel bar produced by the conventional method; during aging of three months, the fluctuation values of the Rm value and the Rel value are less than 10MPa; and the steel bar has excellent welding performance and good corrosion-proof property.

Description

technical field [0001] The invention relates to a chromium-nitrogen micro-alloyed steel bar and a production process thereof, in particular to a HRB500E steel bar with chromium and nitrogen micro-alloying treatment and a production process thereof. Background technique [0002] At present, there are three types of production processes for HRB500MPa steel bars. One is the carbon-manganese steel system composition design mainly based on 20MnSi, using manganese and silicon-based iron alloys for manganese and silicon alloying, using vanadium-iron or vanadium-nitrogen alloys for vanadium microalloying, and using niobium-iron alloys for niobium microalloying. Alloying, its main components control [Mn] between 1.3-1.6%, [Si] between 0.45-0.80%, [C] between 0.17-0.25%, [V] between 0.08-0.12% Sometimes [Nb] is controlled between 0.05-0.12%, or vanadium + niobium composite alloying is used. Yield strength (Rel) ≥ 500MPa, tensile strength (Rm) ≥ 630MPa, reduction of area (A) ≥ 16%, m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/18C22C38/26C22C38/24C22C33/06C21D8/08
Inventor 吴光亮
Owner 长沙东鑫环保材料有限责任公司
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