Production method of high-strength and long-fatigue-life spring steel

A fatigue life and production method technology, applied in the field of metallurgy, can solve the problems of inability to meet ultra-high cycle fatigue life, poor plastic deformation of inclusions, influence of plastic deformation ability of inclusions, etc., to increase investment and production costs, and reduce alloy content. , the effect of reducing production costs

Inactive Publication Date: 2018-03-02
HUNAN VALIN XIANGTAN IRON & STEEL CO LTD
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  • Abstract
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  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, there are very few researches on the use of low-alkalinity refining slag for spring steel in the world. Most of the papers mainly study the control of the number of inclusions and the influence of the plastic deformation capacity of inclusions on the high alkalinity of refining slag.
For example, the 55SiCrA valve spring produced by major steel mills in China mainly creates slag through high alkalinity (binary alkalinity greater than 2.5), and improves the purity of molten steel by controlling the size and quantity of inclusions, but they remain in the steel without being removed. The plastic deformation of the inclusions is poor, which cannot meet the requirements of ultra-high cycle fatigue life

Method used

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  • Production method of high-strength and long-fatigue-life spring steel
  • Production method of high-strength and long-fatigue-life spring steel
  • Production method of high-strength and long-fatigue-life spring steel

Examples

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example 1

[0024] The production method of high-strength and high-fatigue life spring steel, the chemical composition of steel is: carbon=0.56%, silicon=1.45%, manganese=0.62%, phosphorus=0.009%, sulfur=0.010%, aluminum=0.004%, Chromium = 0.68%, titanium = 0.0033%, niobium = 0.013%, and the rest is Fe and unavoidable impurities.

[0025] Smelting: Converter tapping [P]=0.006%, [C]=0.10%, using LF+VD refining process, LF furnace refining process argon blowing, slag deoxidation, first add 500kg of alkaline slag, then add acid slag 160kg, refining slag alkalinity CaO / SiO 2 =1.2; VD vacuum degassing treatment, the vacuum degree is below 0.5tor, the vacuum holding time is 21min, the outbound molten steel [H]=1.7ppm, and the constant [O]=15ppm;

[0026] Continuous casting: full protection casting is adopted, the superheat of the tundish is 28°C, the fluctuation of the liquid level is controlled at ±2.5%, the size of the slab is 150*150mm; the slab [N]=35ppm.

[0027] The surface of the slab ...

example 2

[0030] The production method of high-strength and high-fatigue life spring steel, the chemical composition of the steel is: carbon = 0.56%, silicon = 1.42%, manganese = 0.65%, phosphorus = 0.008%, sulfur = 0.011%, aluminum = 0.0041%, Chromium = 0.69%, titanium = 0.0044%, niobium = 0.005%, and the rest is Fe and unavoidable impurities.

[0031] Smelting: Converter tapping [P]0.007%, [C]0.11%, using LF+VD refining process, LF furnace refining the whole process of argon blowing, slag deoxidation, first add 520Kg of basic slag, then add 165kg of acidic slag, Basicity of refining slag CaO / SiO 2 =1.1; VD vacuum degassing treatment, when the vacuum degree is below 0.5tor, the vacuum holding time is 20min, the outbound molten steel [H] 1.6ppm, [O] 11ppm; The surface fluctuation is controlled at ±2.8%, and the billet size is 150mm×150mm. Slab [N]=34ppm.

[0032] The surface of the billet is first polished with pellets, and then the defect mark is detected by magnetic particle inspec...

example 3

[0035] The production method of high-strength and high-fatigue life spring steel, the chemical composition of the steel is: carbon=0.58%, silicon=1.47%, manganese=0.63%, phosphorus=0.0010%, sulfur=0.008%, aluminum=0.0047%, Chromium = 0.69%, titanium = 0.0046%, niobium = 0.007%, and the rest is Fe and unavoidable impurities.

[0036] Smelting: Converter tapping [P]=0.009%, [C]=0.08%, using LF+VD refining process, LF furnace refining whole process of argon blowing, slagging and deoxidation, adding 480kg of basic slag first, then adding acidic slag 180kg, refining slag alkalinity CaO / SiO 2 =1.0; VD vacuum degassing treatment, when the vacuum degree is below 0.5tor, the vacuum holding time is 20min, the outbound molten steel [H]=1.1ppm, [O]=11ppm; continuous casting adopts full protection casting, and the superheat of the tundish is 27℃ , the liquid level fluctuation is controlled at ±2.9%, the billet size is 150mm×150mm, and the billet [N]=31ppm.

[0037] Polish the surface of ...

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Abstract

The invention discloses a production method of high-strength and long-fatigue-life spring steel. The chemical compositions of the spring steel comprise, by weight, 0.51-0.59% of carbon, 1.40-1.60% ofsilicon, 0.50-0.80% of manganese, 0.012% or less of phosphorus, 0.010% or less of sulphur, 0.02% of or less niobium, 0.005% or less of titanium, 0.005% or less of aluminum, 0.50-0.80% of chromium andthe balance Fe and unavoidable impurities. The production method comprises the technological steps that (1) smelting is conducted; (2) continuous casting is conducted; (3) coping is conducted; and (4)rolling and controlled cooling are conducted, and the high-strength and long-fatigue-life wire spring steel taking a sorbite structure as a matrix is produced. According to the production method of the high-strength and long-fatigue-life spring steel, the diameter of a representative steel type, namely an X55SiCrA steel wire rod, is 5.5 mm, the tensile strength is 1000 MPa or over, the area reduction is 40% or over, the grade A, the grade B, the grade C and the grade D of inclusions are all smaller than 1.0, a DS type inclusion is not contained, and the using requirements of a valve spring for an automobile can be well met.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and relates to a production method of spring steel with high strength and high fatigue life. Background technique [0002] Spring steel is an important mechanical part with a wide range of uses in many machinery industries such as automobiles. Fatigue fracture is often the most important form of damage to springs. Taking the automobile industry as an example, as the car industry gradually shifts from a popular type to a mid-to-high-end and family car type, automobile engines and other equipment are developing towards high speed, high load, low energy consumption, low pollution and light weight, which in turn affects the automobile's The requirements of the key parts valve spring are getting higher and higher. [0003] At present, there are very few studies on the use of low-basic refining slag for spring steel in the world. Most of the papers mainly study the control of the number of inclusion...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/34C22C38/02C22C38/04C22C38/26C22C38/18C21C7/06C21C7/064C21C7/10C21D8/06
CPCC22C38/34C21C7/06C21C7/064C21C7/10C21C2007/0093C21D8/065C22C38/02C22C38/04C22C38/18C22C38/26
Inventor 王旭冀罗登陈军肖冬邢耀进林丹黄伟成朱建成
Owner HUNAN VALIN XIANGTAN IRON & STEEL CO LTD
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