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Process for smelting low-cost X70 pipeline steel moderate-thickness plate blanks

A pipeline steel and thick slab technology, which is applied in the smelting process of medium and thick slabs of low-cost X70 pipeline steel, and in the field of smelting technology, can solve problems such as consumption and achieve the effects of reducing production costs, reducing alloy costs, and low process costs

Active Publication Date: 2013-01-09
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The patent with the application number 200810079325.8 discloses a low-cost high-performance X70 pipeline steel and its production method. The invention mainly includes the addition of Mn, Si, Nb, and V alloys in the chemical composition formula, and refines the grains through the controlled rolling process. Achieve the purpose of X70 pipeline steel strength and toughness, and solve the problem of consuming precious metals such as Mo and Ni in production

Method used

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] The process route is: molten iron pretreatment - converter smelting - LF furnace refining - slab continuous casting.

[0016] Hot metal pretreatment: The hot metal desulfurization pretreatment process is adopted to remove the desulfurization slag on the top of the de-iron ladle after treatment, and the [S] in the hot metal after pretreatment is 0.003%.

[0017] Converter smelting: control the composition and temperature hit of the end point of the converter, the composition of the end point of the converter and the temperature hit at the same time without supplementary blowing, the composition control of the end point of molten steel: [C]=0.042%, [P]=0.007%, [S]=0.008%, T =1651°C, aluminum is used for strong deoxidation when tapping, and tapping is carried out with slag blocking. The end temperature of the converter is 1640°C-1700°C.

[0018] LF furnace refining: control the amount of refining slag added, the flow rate of argon gas blown at the bottom of the ladle, and...

Embodiment 2

[0021] The process route is: molten iron pretreatment - converter smelting - LF furnace refining - slab continuous casting.

[0022] Hot metal pretreatment: The hot metal desulfurization pretreatment process is adopted to remove the desulfurization slag on the top of the de-iron ladle after treatment, and the [S] in the hot metal after pretreatment is 0.002%.

[0023] Converter smelting: control the composition and temperature of the end point of the converter, the composition and temperature of the end point of the converter are hit at the same time without supplementary blowing, the end point control of molten steel composition: [C]=0.037%, [P]=0.010%, [S]=0.009%, T =1643℃, aluminum is used for strong deoxidation when tapping, and tapping is carried out with slag blocking.

[0024] LF furnace refining: control the amount of refining slag added, the flow rate of argon gas blown at the bottom of the ladle, and ensure the final slag oxidation (FeO+MnO)=0.7%, basicity (CaO) / (SiO...

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Abstract

The invention discloses a process for smelting low-cost X70 pipeline steel moderate-thickness plate blanks. The process comprises the steps of molten iron pretreatment, converter smelting, LF furnace refining and plate blank continuous casting. In the process, C is 0.04%-0.08%, Mn is 1.40%-1.80%, Nb is 0.04%-0.08%, Cr is 0.2%-0.3%, P <= 0.015%, S <= 0.002%, N <= 60ppm, H <= 3.0ppm, and precious alloys Ni and Mo are not added. An RH (VD) vacuum treatment process is omitted, calcium treatment is performed after LF treatment, and inclusions are ensured to fully float upwards. The plate blank continuous casting step adopts a dynamitic soft-reduction process, and the center segregation of continuous casting blanks is controlled to be B-grade 1.0 or lower. The process for smelting the low-cost X70 pipeline steel moderate-thickness plate blanks is low in molten alloy cost and process cost and capable of achieving batch and industrial production of low-cost X70 pipeline steel moderate-thickness plates.

Description

technical field [0001] The invention belongs to the field of steelmaking and relates to a smelting process, in particular to a low-cost X70 pipeline steel medium-thick slab smelting process. Background technique [0002] In recent years, with the increasing demand for oil and natural gas in various countries in the world and the rapid development of oil and gas pipeline construction, high-strength toughness pipeline steel has become the development trend of high-pressure, long-distance oil and gas pipelines. In projects such as the Second East Pipeline, X70 medium-thick plates for pipeline steel have been used in large quantities, and the production technology has also tended to be stable and mature. Although the chemical composition and production process of X70 steel grade pipeline steel of each production unit are different, a large amount of precious metal alloys such as Nb, Ni, Mo, and Cu are added, and the RH (VD) vacuum degassing process is used for smelting, which co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/26C22C38/38C22C33/04C21C5/28C21C7/00B22D11/00
Inventor 潘中德姜金星樊振亚孟令东曹余良顾鑫刘梦冉
Owner NANJING IRON & STEEL CO LTD
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