Steel having excellent toughness in welding heat affected zone, and manufacturing method thereof

A technology of welding heat influence and manufacturing method, which is applied in the field of steel, can solve problems such as toughness and easy deterioration, and achieve the effect of improving HAZ toughness and toughness

Inactive Publication Date: 2012-07-25
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These steel materials are generally joined by welding, but in the welded joints, especially the HAZ, there is a problem that the toughness is easily deteriorated due to the influence of heat during welding.

Method used

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  • Steel having excellent toughness in welding heat affected zone, and manufacturing method thereof
  • Steel having excellent toughness in welding heat affected zone, and manufacturing method thereof
  • Steel having excellent toughness in welding heat affected zone, and manufacturing method thereof

Examples

Experimental program
Comparison scheme
Effect test

experiment example 1

[0155] In Experimental Example 1, the relationship between the requirements specified in (a) to (c) above and HAZ toughness was studied, and in Experimental Example 2, the above (d) and (e) The relationship between the elements and HAZ toughness is studied.

[0156] [Experimental example 1]

[0157] Using a vacuum melting furnace (capacity 150kg), under the conditions shown in the following Table 1, the test steel (the balance is iron and unavoidable impurities) with the composition (mass %) shown in the following Table 2 and Table 3 was melted. , cast into 150kg ingots and cooled. Thereafter, heating and rolling are performed to produce thick steel plates. In addition, among the test steels shown in Table 2 and Table 3 below, it was confirmed that the total O content of the test steel satisfying the requirements specified in the present invention was in the range of 0.0005 to 0.010%.

[0158] When melting the above test steel in a vacuum melting furnace, adjust the composi...

experiment example 2

[0187] Regarding Nos. 1, 3, 8, 11, and 13 to 16 shown in Table 4 above, the relationship between the composition of each inclusion contained in the steel material and the HAZ toughness was investigated.

[0188] The composition of each inclusion contained in the steel material was measured in the following procedure. That is, in the same manner as in Experimental Example 1 above, using EPMA ("JXA-8500F (device name)") manufactured by JEOL Datum Co., Ltd., the surface of the cut sample was observed, and the inclusions with an equivalent circle diameter of 0.1 μm or more were quantitatively analyzed. ingredients.

[0189] As an example of quantitative analysis, the composition of each inclusion contained in No. 1 steel shown in Table 4 above was analyzed, and the results are shown in image 3 middle. The X-axis represents the number of observed inclusions, and the Y-axis represents the composition of each inclusion, and each component is distinguished by color. at 1.56cm 2 I...

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Abstract

The invention provides a steel having excellent HAZ toughness when executing large linear energy welding with the linear energy being more than 50 KJ / mm, and a manufacturing method thereof. The steel comprises C, Si, Mn, P, S, Al, Ti, REM, Ca, Zr, N, O and the rest being Fe and unavoidable impurities; (a) the steel comprises oxide containing Zr, REM and Ca; (b) when measuring the composition of all oxide contained in the steel and converting into independent oxide, the condition that the steel comprises 5-50% og ZrO2, 5-50% of oxide of REM (if representing REM by taking M as a marker, being M2O3), and below 50% of CaO (not comprising 0%) is satisfied; and (c) in all impurities contained in the steel, the number of the impurities with a volume diameter being 0.1-2 mum is above 120 in each 1mm2 of a viewing field area; the number of the oxide with the volume diameter being more than 3 mum is below 5 in each 1mm2 of the viewing field area, and the number of the oxide with the volume diameter being more than 5 mum is below 5 in each 1mm2 of the viewing field area.

Description

technical field [0001] The present invention relates to steel materials used in bridges, high-rise buildings, ships, etc., and in particular to steel materials having excellent toughness at parts affected by heat during welding (hereinafter referred to as "welding heat-affected zone" or "HAZ") and their Manufacturing method. Background technique [0002] The characteristics required for steel materials used in bridges, high-rise buildings, ships, etc. have become increasingly stringent in recent years, and exceptionally good toughness is required. These steel materials are generally joined by welding, but there is a problem that the welded joint portion, especially the HAZ, is affected by heat during welding, and the toughness tends to deteriorate. This deterioration in toughness becomes more pronounced as the heat input during welding increases. The reason for this is that, when the heat input during welding increases, the cooling rate of the HAZ slows down and the hardena...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/14C21C7/00
CPCC21C7/06C22C38/001C22C38/002C22C38/005C22C38/02C22C38/04C22C38/06C22C38/14
Inventor 杉谷崇出浦哲史冈崎喜臣名古秀德太田裕己
Owner KOBE STEEL LTD
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