Steel for large heat input welding and method for improving toughness of heat-affected zone of steel

A large heat input welding and heat-affected zone technology, applied in the direction of process efficiency improvement, metal rolling, temperature control, etc., can solve the problem of low toughness of the zone

Active Publication Date: 2020-12-29
LONGYAN UNIV
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Problems solved by technology

[0004] In order to solve the problem of low toughness in the heat-affected zone of the existing high-heat-input welding steel, th

Method used

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  • Steel for large heat input welding and method for improving toughness of heat-affected zone of steel
  • Steel for large heat input welding and method for improving toughness of heat-affected zone of steel

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Embodiment Construction

[0029] A method for improving the toughness of the heat-affected zone of steel for welding with large heat input, the chemical composition of which is as follows: C: 0.08%, Si: 0.23%, Mn: 1.80%, Al: 0.035%, P: ≤0.015%, S: ≤0.013 %, Ti: 0.07%, B: 0.002, and the balance is Fe, wherein the balance of Fe contains trace unavoidable impurities.

[0030] The above-mentioned method for improving the toughness of the heat-affected zone of steel for welding with large heat input, the specific steps are as follows:

[0031] (1) Smelting: According to the composition design of the high heat input welding steel, various raw materials are alloy smelted at 1600°C, molten steel is smelted, and steel ingots are obtained by pouring;

[0032] (2) Rolling: The steel ingot was heated to 1200 °C and held for 2 h. After fully austenitized, the steel ingot was subjected to 2 rough rolling passes. The initial rolling temperature of the rough rolling was 1100 °C, and the final rolling temperature was 1...

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Abstract

The invention discloses steel for large heat input welding and a method for improving the toughness of a heat-affected zone of the steel. According to the scheme, through reasonable component design,pouring, rolling and cooling process link control, fine and dispersed (Ti, Si, Al, Mn) O and MnS type inclusions are formed in a base metal, the size mostly ranges from 0.5 [mu]m to 2 [mu]m, and a large number of slender acicular ferrite (AF) structures are generated with the inclusions used as cores, so that the base metal has the relatively-high mechanical properties. After large heat input welding of 200-800 kJ/cm, the AF structures in the welding affected zone (HAZ) are converted into equiaxed ferrite structures, the subzero-40-DEG C low-temperature impact toughness of the HAZ is not reduced but slightly increased, the toughness of the HAZ is not affected by welding heat input, the welding efficiency is substantially improved, and meanwhile, the HAZ has the stable mechanical properties.

Description

technical field [0001] The invention belongs to the technical field of low-alloy high-strength steel welding, and specifically relates to a steel for welding with large heat input and a method for improving the toughness of a heat-affected zone, which can improve welding efficiency and improve the toughness of the heat-affected zone. Background technique [0002] In the field of large-scale equipment and machinery manufacturing such as shipbuilding, offshore platforms, and oil storage tanks, welding, as an important part of production and processing, has been paid more and more attention. cost. In this context, large heat input welding methods such as gas-electric vertical welding, electroslag welding, and submerged arc welding have been widely used in the related manufacturing fields of medium and thick plates. The increase in the peak temperature of the thermal cycle leads to a slow cooling rate, which can easily cause the grain structure of the welding heat-affected zone...

Claims

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Application Information

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IPC IPC(8): B21B1/22B21B37/74C22C38/00C22C38/02C22C38/04C22C38/06C22C38/14
CPCB21B1/22B21B37/74C22C38/02C22C38/04C22C38/06C22C38/14C22C38/002B21B2001/225Y02P10/20
Inventor 宋峰雨
Owner LONGYAN UNIV
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