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Method for enhancing impact toughness of quenched and tempered steel

An impact toughness, quenched and tempered steel technology, applied in heat treatment equipment, heat treatment process control, manufacturing tools, etc., can solve problems such as unfavorable resource conservation, limited potential for purifying molten steel, expensive filter accessories, etc. The effect of increased strength, elongation and shrinkage

Inactive Publication Date: 2014-08-20
SICHUAN FAST STAINLESS STEEL CASTING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] However, as far as the current technology is concerned, increasing the alloy content will increase the cost, which is not conducive to the economical utilization of resources, and is at a disadvantage in market competition
However, the potential for purifying molten steel is limited and requires more complex processes and expensive filter accessories

Method used

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  • Method for enhancing impact toughness of quenched and tempered steel
  • Method for enhancing impact toughness of quenched and tempered steel
  • Method for enhancing impact toughness of quenched and tempered steel

Examples

Experimental program
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Effect test

Embodiment 1

[0039] Take LCB low-temperature carbon steel ASTM A352 with a wall thickness of 50mm, heat it to 880°C at a heating rate of 250°C / hour, and quench it once in 30°C water after holding for 4 hours; then reheat the material at a speed of 250°C / hour After heating to 790°C, continue to keep warm for 4 hours and then perform secondary quenching in 30°C water; continue to temper at a rate of 250°C / hour to 690°C, keep warm for 5 hours, and then cool to room temperature in 30°C water .

[0040] The performance of the quenched and tempered steel obtained in the final test is 5% higher than the raw material in strength, 10% in elongation and shrinkage, and 32% in impact toughness.

Embodiment 2

[0042] Take 3.5% nickel steel ASTM A352 with a wall thickness of 75mm, heat it to 900°C at a heating rate of 300°C / hour, and quench it in water at 25°C after holding for 5 hours; then reheat the material at a speed of 300°C / hour After heating to 810°C, continue to keep warm for 5 hours, and then perform secondary quenching in 25°C water; continue to temper at a rate of 300°C / hour to 700°C, keep warm for 6 hours, and then cool to room temperature in 25°C water .

[0043] The performance of the quenched and tempered steel obtained in the final test is 6% higher than the raw material in strength, 8% in elongation and shrinkage, and 35% in impact toughness.

Embodiment 3

[0045] Take quenched and tempered steel with a wall thickness of 60mm, heat it to 890°C at a heating rate of 350°C / hour, and quench it in water at 25°C after holding for 4.4 hours; then reheat the material to 800°C at a rate of 350°C / hour ℃, keep warm for 4.4 hours and then perform secondary quenching in 25 ℃ water; continue tempering at a rate of 300 ℃ / hour to 700 ℃ and keep warm for 5.4 hours, then cool to room temperature in 25 ℃ water.

[0046] The performance of the quenched and tempered steel obtained in the final test is 8% higher than that of the raw material, the elongation and shrinkage are both increased by 9%, and the impact toughness is increased by 32%.

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Abstract

The invention relates to the field of metallurgy, particularly a method for enhancing impact toughness of quenched and tempered steel, which comprises the following steps: 1. heating quenched and tempered steel or carbon steel capable of quenching and tempering to 60-100 DEG C above Ac3, holding for some time, and carrying out primary quenching; 2. heating the material to 50-80 DEG C above Ac1, holding for some time, and carrying out secondary quenching; and 3. continuing temper to 10-20 DEG C below Ac1, holding for the time which is 1 hour longer than the previous time, and cooling to normal temperature, wherein the holding time is computed according to the maximum wall thickness of the raw material, and the computing formula is H=2+M / 25 (H is holding time of which the unit is h, and M is the wall thickness of the product, of which the unit is mm). The invention aims to provide a method for enhancing impact toughness of quenched and tempered steel; and the method has the advantage of low technical cost and can obviously enhance the impact toughness of the quenched and tempered steel.

Description

technical field [0001] The invention relates to the field of metallurgy, in particular to a method for improving the impact toughness of quenched and tempered steel. Background technique [0002] The so-called quenched and tempered steel generally refers to medium carbon steel with a carbon content of 0.3-0.6%. Generally, the parts made of this kind of steel are required to have good comprehensive mechanical properties, that is, to maintain high strength while having good plasticity and toughness. People often use modulation treatment to achieve this purpose, so people are used to This type of steel is called quenched and tempered steel. A large number of structural parts on various machines use quenched and tempered steel, which is the most widely used type of steel in structural steel. Quenched and tempered steel is one of the important materials widely used in machinery manufacturing. [0003] However, parts made of quenched and tempered steel in some fields are often ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18C21D11/00
Inventor 李伟周凯文曾光前吴枝峰
Owner SICHUAN FAST STAINLESS STEEL CASTING