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Smelting method for directly turning non-quenched and tempered steel

A technology of non-quenched and tempered steel and smelting method, applied in the direction of manufacturing converters, etc., can solve the problems of high scrap rate, difficult to control, difficult to control, etc., achieve high strength and high toughness, ensure service life, and ensure the effect of stable use

Pending Publication Date: 2021-11-16
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the sulfur and nitrogen in the steel are unstable in the high-temperature molten steel, it is not easy to control during the smelting process.
Non-quenched and tempered steel production enterprises generally use electric furnace-refining process to produce non-quenched and tempered steel, and at the same time add nitrogen-rich alloy and sulfur-containing alloy (or sulfur feeding line) to ensure the nitrogen and sulfur content in the steel, and the yield is low. The cost is high and it is not easy to control stably, resulting in a high scrap rate
The tensile strength level of existing non-quenched and tempered steel bars is difficult to reach 900MPa, which cannot meet the strength and impact performance requirements of heavy-duty vehicle axle shafts
[0003] Existing patent: A smelting method of direct turning non-tempered steel mainly introduces a production mode of direct turning non-quenched and tempered steel through the converter-LF-RH-continuous casting-rolling route, which features simple production organization requirements, The direct turning non-adjusted steel production method is achieved by controlling the continuous casting casting speed and rolling process. Stability and service life of adjusted steel products

Method used

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  • Smelting method for directly turning non-quenched and tempered steel

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] The method for smelting high-strength non-quenched and tempered steel provided in this embodiment includes the following steps:

[0054] (1) Pretreatment of molten iron (not necessary), can be adjusted according to the condition of molten iron entering the furnace: reduce the burden of desulfurization in the LF treatment process, and improve the purity of molten steel;

[0055] (2) Converter smelting control: the mass percentage of C at the end point is controlled at 0.184% or the oxygen level of tapping TSO is 300ppm, the tapping temperature is 1630°C, and the oxygen level is strictly controlled to create good conditions for the subsequent process;

[0056] (3), converter tapping control:

[0057] a. Bottom agitation: Turn on the bottom agitation and nitrogen blowing of the converter before the molten steel is tapped to increase the N content in the molten steel, reduce the oxidation of the molten steel and the P content of the molten steel;

[0058] b. Control of sla...

Embodiment 2

[0072] The method for smelting high-strength non-quenched and tempered steel provided in this embodiment includes the following steps:

[0073] (1) Hot metal pretreatment (not necessary), can be adjusted according to the molten iron into the furnace (such as hot metal S ≤ 0.01%, desulfurization is not required): reduce the desulfurization burden in the LF treatment process, and improve the purity of molten steel;

[0074] (2) Converter smelting control: End point control C: 0.254% (tapping TSO: 220ppm), tapping temperature: 1625°C, strictly control the oxygen level, and create good conditions for the subsequent process;

[0075] (3), converter tapping control:

[0076] a. Bottom agitation: Turn on the bottom agitation and nitrogen blowing of the converter before the molten steel is tapped to increase the N content in the molten steel, reduce the oxidation of the molten steel and the P content of the molten steel;

[0077] b. Control of slag removal: slag dumping before the co...

Embodiment 3

[0091] The preparation method of the high-purity wind power fastener provided in this embodiment includes the following steps:

[0092] (1) Hot metal pretreatment (not necessary), can be adjusted according to the molten iron into the furnace (such as hot metal S≤0.01% without desulfurization): reduce the burden of desulfurization in the LF treatment process, and improve the purity of molten steel;

[0093] (2) Converter smelting control: End point control C: 0.292% (or tapping TSO oxygen level 180ppm), tapping temperature 1630°C, strictly control the oxygen level, and create good conditions for the subsequent process;

[0094] (3) Converter tapping control:

[0095] a. Before the molten steel is tapped, turn on the bottom of the converter to stir and blow nitrogen, increase the N content in the molten steel, reduce the oxidation of the molten steel and the P content of the molten steel;

[0096] b. Control of slag removal: slag dumping before the converter is tapped, and a do...

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Abstract

The invention discloses a smelting method for directly turning non-quenched and tempered steel. The smelting method belongs to the field of mechanical part production, and specifically comprises the following steps: (1), converter metallurgy; (2) converter tapping; (3) deoxidizing and alloying; (4) LF treatment; (5) RH treatment; and (6) continuous casting: finally smelting to generate the directly turned non-quenched and tempered steel. The non-quenched and tempered steel smelted through the method is high in strength and toughness, and the service life is prolonged. According to the non-quenched and tempered steel provided by the invention, the total oxygen content can be stably controlled to be 15 ppm or below, the H content is 1.5 ppm or below, the N content is 100 ppm or above, the H content and the O content in the steel are effectively reduced, the N content is controlled, the product quality is improved, the high strength and the high toughness of the produced non-quenched and tempered steel are guaranteed, and the use stability and the service life of an oil cylinder piston rod are guaranteed.

Description

technical field [0001] The invention belongs to the field of mechanical component production and relates to a smelting method for directly turning non-quenched and tempered steel. Background technique [0002] The non-quenched and tempered steels that have been developed at present generally have low tensile strength, and the tensile strength cannot meet the high tensile strength requirements of the current heavy-duty vehicle axle shafts, thus limiting the use of non-tempered steels in the bar steel field that requires high performance Non-quenched and tempered steel is widely used because it does not require quenching and tempering treatment, and only needs to control the rolling (forging) process and the cooling rate after rolling (forging) to obtain the required strength, toughness and cutting performance. In the rapidly developing automobile industry, it is used to manufacture crankshafts, connecting rods, steering knuckles, front beams and other parts that require stren...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C5/28C21C7/06C21C7/00C21C7/10
CPCC21C5/28C21C7/06C21C7/0006C21C7/0056C21C7/10
Inventor 李天学胡志勇李林鲁川陈鹏涛刘义韦士琨
Owner NANJING IRON & STEEL CO LTD
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