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A kind of steel for ultra-large and high-strength fasteners and its production method

A production method and technology of fasteners, which are applied in the field of alloy steel smelting, can solve the problems of affecting the weight of fasteners, insufficient cold heading, etc., and achieve good cold drawing performance, no spheroidizing annealing, inclusion level small effect

Active Publication Date: 2019-07-16
武汉钢铁有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the cold heading property of this steel is not good enough. In the production of large fasteners, due to the limitation of steel hardenability (that is, the thickness of hardened layer), it directly affects the weight of fasteners.

Method used

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  • A kind of steel for ultra-large and high-strength fasteners and its production method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029]A steel for super-large and high-strength fasteners, the chemical composition of which is: C: 0.39%, Si: 0.10%, Mn: 0.90%, P: 0.020%, S: 0.010%, Als: 0.06%, Cr : 1.20%, Mo: 0.60%, V: 0.50%, Nb: 0.06%, B: 0.0030%, and the rest are Fe and impurity elements. Its process includes the following steps:

[0030] 1) Hot metal desulfurization: The mass percentage of each element in the incoming hot metal is: S≤0.025%, Mn≤0.30%, Cu≤0.060%, Si≤0.80%, the temperature of the incoming molten iron is ≥1250°C, and the quality of sulfur in the molten iron is controlled Percentage S≤0.001%;

[0031] 2) Converter smelting: the end-point carbon control target is 0.10%, the slag is blocked for tapping, the thickness of the slag layer is ≤50mm, the final slag basicity is 3.0-4.0, the tapping temperature is controlled at 1650-1690°C, and the tapping time is ≥3min;

[0032] 3) Deoxidation alloying: Alloys are added when 1 / 3 of the molten steel is tapped, and the alloy addition sequence is: Al...

Embodiment 2

[0040] A steel for super-large and high-strength fasteners, the chemical composition of which is: C: 0.41%, Si: 0.08%, Mn: 0.85%, P: 0.015%, S: 0.008%, Als: 0.05%, Cr : 1.15%, Mo: 0.55%, V: 0.45%, Nb: 0.05%, B: 0.0025%, and the rest are Fe and impurity elements. Its process includes the following steps:

[0041] 1) Hot metal desulfurization: The mass percentage of each element in the incoming hot metal is: S≤0.025%, Mn≤0.30%, Cu≤0.060%, Si≤0.80%, the temperature of the incoming molten iron is ≥1250°C, and the quality of sulfur in the molten iron is controlled Percentage S≤0.001%;

[0042] 2) Converter smelting: the end-point carbon control target is 0.10%, the slag is blocked for tapping, the thickness of the slag layer is ≤50mm, the final slag basicity is 3.0-4.0, the tapping temperature is controlled at 1650-1690°C, and the tapping time is ≥3min;

[0043] 3) Deoxidation alloying: Alloys are added when 1 / 3 of the molten steel is tapped, and the alloy addition sequence is: A...

Embodiment 3

[0051] A steel for super-large and high-strength fasteners, the chemical composition of which is: C: 0.42%, Si: 0.06%, Mn: 0.80%, P: 0.013%, S: 0.007%, Als: 0.04%, Cr : 1.10%, Mo: 0.50%, V: 0.40%, Nb: 0.04%, B: 0.0020%, and the rest are Fe and impurity elements. Its process includes the following steps:

[0052] 1) Hot metal desulfurization: The mass percentage of each element in the incoming hot metal is: S≤0.025%, Mn≤0.30%, Cu≤0.060%, Si≤0.80%, the temperature of the incoming molten iron is ≥1250°C, and the quality of sulfur in the molten iron is controlled Percentage S≤0.001%;

[0053] 2) Converter smelting: the end-point carbon control target is 0.10%, the slag is blocked for tapping, the thickness of the slag layer is ≤50mm, the final slag basicity is 3.0-4.0, the tapping temperature is controlled at 1650-1690°C, and the tapping time is ≥3min;

[0054] 3) Deoxidation alloying: Alloys are added when 1 / 3 of the molten steel is tapped, and the alloy addition sequence is: A...

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Abstract

The invention belongs to the field of alloy steel smelting of iron and steel industries, and particularly provides an extra large high strength steel for a fastening part and a production method. The steel for the fastening part comprises, by mass, 0.43-0.47% of C, no more than 0.10% of Si, 0.60-0.90% of Mn, no more than 0.020% of P, no more than 0.010% of S, 0.02-0.06% of Als, 0.90-1.20% of Cr, 0.30-0.60% of Mo, 0.20-0.50% of V, 0.02-0.06% of Nb, 0.001-0.003% of B, and the balance Fe and unavoidable impurities. The production method of the steel comprises the following steps of molten iron desulfurization, converter smelting, deoxidation alloying, argon blowing, LF furnace treatment, continuous casting, casting blank heating, high line or bar rolling and stelmor control cooling. Steel inclusion produced through the method is low in grade, the extra large high strength steel is uniform in texture, good in cold heading property and hardenability and good in delayed fracture resistance, the tensile strength of wire rods reaches above 850 MPa, the depth of hardening layers of produced products reaches above 10 mm, the problem that the diameter of the large-scale fastening part needs to be increased to meet the tolerance requirements is solved to a certain extent, and the method is suitable for manufacturing the large-scale high strength fastening part.

Description

technical field [0001] In the field of alloy steel smelting in the iron and steel industry, the invention specifically provides a steel for super-large and high-strength fasteners and a production method. Background technique [0002] Fasteners are the basic components of the machinery industry, and their quality level determines the development of the national machinery industry. They are widely used in some basic industries, such as automobiles, high-speed rail, metallurgy, and electric power. my country's current fastener steel is in low-end overcapacity, and some high-strength fastener steel cannot meet the demand. With the rapid development of high-speed rail transit in my country, the demand for rail transit fastener steel has also increased significantly, and the requirements for the strength and toughness of fastener steel have also been continuously improved. [0003] The production of large-scale fasteners generally needs to be quenched and tempered. In the past, ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/22C22C38/24C22C38/26C22C38/32C22C33/04C21D8/06
CPCC21D8/065C22C33/04C22C38/02C22C38/04C22C38/06C22C38/22C22C38/24C22C38/26C22C38/32
Inventor 帅习元仇东丽鲁修宇周勇黄静张帆黄成红贾万军
Owner 武汉钢铁有限公司
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