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High-strength steel sheet excellent in resistance to stress-relief annealing and low-temperature joint toughness

A technology for stress relief annealing and high-strength steel plates, applied in furnace types, furnaces, heat treatment furnaces, etc., can solve the problem of low temperature toughness reduction of HAZ, and achieve the effect of inhibiting strength reduction and excellent low temperature joint characteristics

Inactive Publication Date: 2012-02-29
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this technology, although Cr is supposed to be contained in a relatively wide range, the actual Cr content is only 0.29% or more, and it is fully expected that the low-temperature toughness of the HAZ will decrease.

Method used

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  • High-strength steel sheet excellent in resistance to stress-relief annealing and low-temperature joint toughness
  • High-strength steel sheet excellent in resistance to stress-relief annealing and low-temperature joint toughness
  • High-strength steel sheet excellent in resistance to stress-relief annealing and low-temperature joint toughness

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Embodiment

[0060] Hereinafter, the present invention is described in more detail through the examples, but the following examples do not limit the nature of the present invention, and can also be appropriately changed and implemented within the scope of being able to meet the purpose of the foregoing and the following, and these are all included in the technology of the present invention. within range.

[0061] Among the various chemical compositions shown in Table 1 below, converter smelting and continuous ingot casting were carried out, and Ar 3 Rolling is completed at a temperature equal to or higher than the transformation point, and accelerated cooling (cooling rate: about 3 to 30° C. / second) is performed from this temperature to produce various steel sheets. Each of the obtained steel sheets was subjected to SR treatment at 615° C. for 23 hours (the value of P in the above formula (3) was 18.97).

[0062] Also in Table 1, the Ar of each steel grade is also shown 3 These values ​​...

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Abstract

A high-strength steel sheet is provided which, even when subjected to long-term stress-relief annealing after welding, decreases little in strength and which has satisfactory low-temperature HAZ toughness. The high-strength steel sheet has a chemical composition adequately regulated and has a CP value defined by the following equation (1) of 5.40% or higher and a carbon equivalent (Ceq) defined by the following equation (2) of 0.45% or lower. CP value = 125[Ti]+111[Nb]+60[V]+15[Mo] (1) ([Ti], [Nb], [V], and [Mo] indicate the contents (mass%) of Ti, Nb, V, and Mo, respectively.) Ceq=[C]+[Mn] / 6+([Cr]+[Mo]+[V]) / 5+([Cu]+[Ni]) / 15 (2) ([C], [Mn], [Cr], [Mo], [V], [Cu], and [Ni] indicate the contents (mass%) of C, Mn, Cr, Mo, V, Cu, and Ni, respectively).

Description

technical field [0001] The present invention relates to the fact that even when long-term stress-relieving annealing (stress-relief annealing: hereinafter referred to as "SR treatment") is performed after welding, the strength is reduced little, and the welded heat-affected zone (hereinafter referred to as "HAZ") ”) high-strength steel sheet with excellent low temperature toughness. Background technique [0002] In recent years, in the manufacture of large steel pressure vessels (storage tanks), for the purpose of cost reduction, on-site assembly toward overseas storage tanks has been developed. Traditionally, cutting and bending of steel members, assembly (assembly by welding), SR treatment (local heat treatment (local heat treatment)) of some members, and final assembly have generally been carried out at our factory, and then the entire tank has been assembled. Transport to site. [0003] However, due to on-site construction in consideration of efficiency, the content of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00C22C38/14C22C38/58
CPCC22C38/14C21D9/46C22C38/02C22C38/06C22C38/12C22C38/04C21D9/14C21D1/30C22C38/002C22C38/16C22C38/18
Inventor 仮屋崎诚
Owner KOBE STEEL LTD
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