Thick steel sheet having superior fatigue resistance properties in direction of sheet thickness, method for producing same, and fillet welded joint using said thick steel sheet

A technology of plate thickness direction and thick steel plate, which can be used in manufacturing tools, welding equipment, arc welding equipment, etc.

Active Publication Date: 2013-12-18
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The reduction in ductility and toughness of steel sheets can sometimes be prevented by adding a large amount of alloy elements, but it is difficult to avoid the problem of high material costs

Method used

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  • Thick steel sheet having superior fatigue resistance properties in direction of sheet thickness, method for producing same, and fillet welded joint using said thick steel sheet
  • Thick steel sheet having superior fatigue resistance properties in direction of sheet thickness, method for producing same, and fillet welded joint using said thick steel sheet
  • Thick steel sheet having superior fatigue resistance properties in direction of sheet thickness, method for producing same, and fillet welded joint using said thick steel sheet

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0090] The steel materials having the compositions shown in Table 1 were hot-rolled under the conditions shown in Table 2 to form thick steel plates with a plate thickness of 55 to 70 mm. These thick steel plates were subjected to residual stress measurement, tensile test, toughness test, and fatigue test. The test method is as follows.

[0091] (1) Determination of residual stress

[0092] A test piece (size: plate thickness (original thickness of the steel plate) × 12.5mm × 300mm [dimension in the direction of plate thickness × dimension in the direction perpendicular to rolling × direction of rolling) is taken from the obtained thick steel plate for residual stress measurement by X-rays Dimensions]), after performing electrolytic polishing on the measurement surface [12.5mm×300mm surface], measure the residual stress in the thickness direction by X-ray at a pitch of 4mm along the thickness direction. The number of lines measured at a pitch of 4 mm along the plate thicknes...

Embodiment 2

[0102] Fillet welds were produced using a thick steel plate 2 having a chemical composition shown in Table 3, manufactured under the manufacturing conditions shown in Table 4, and having a thickness of 55 to 70 mm with excellent fatigue properties in the thickness direction of the plate and having the characteristics shown in Table 4. head, use figure 2 The three-point bending fatigue test is carried out on the fatigue test piece of the three-point bending fillet welded joint with the shape shown. The test method for confirming the structure, mechanical properties, and fatigue properties in the plate thickness direction of the thick steel plate 2 was performed in the same manner as in Example 1.

[0103] Using the thick steel plate 2 whose characteristics were confirmed by the above tests, in Figure 4 Fillet welded joints were fabricated under the conditions shown, and fatigue tests were performed. As a fatigue test piece, use figure 2 Fatigue test pieces of three-point ...

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Abstract

Provided are: a thick steel sheet that has superior fatigue resistance properties in the direction of sheet thickness and that is favorable for welded steel structures such as pressure vessels; a method for producing the thick steel sheet; and a fillet welded joint using the thick steel sheet. Specifically, the thick steel sheet has a composition that, in a range from one or both of the rolled surfaces of the steel sheet to 4 mm in the direction of sheet thickness, has a compressive residual stress perpendicular to the direction of steel thickness of at least 100 MPa and preferably contains, by mass, 0.03-0.15% of C, no greater than 1.0% of Si, and 1.0-2.0% of Mn; 0.005-0.05% of Ti and/or 0.001-0.05% of Nb; and one or at least two of Cu, Ni, Cr, Mo, V, W, Zr, Ca, B, and no greater than 0.1% of Al.

Description

technical field [0001] The present invention relates to the plate thickness direction suitable for welded steel structures such as ships, marine structures, bridges, buildings, and pressure vessels. A thick steel plate excellent in fatigue resistance, a manufacturing method thereof, and a fillet welded joint using the thick steel plate. Background technique [0002] As steel plates used in welded steel structures such as ships, marine structures, bridges, buildings, and pressure vessels, of course, they must not only have excellent mechanical properties such as strength (strength), toughness (toughness), and weldability (weldability), and for the stable cyclic load (steady cyclic load) during operation, and the unstable cyclic load (unsteady cyclic load) caused by vibrations such as wind (wind) and earthquake (earthquake), it is also required that the steel plate has the ability A characteristic that ensures the structural safety of a structure. Especially in recent years,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00B23K9/02B23K9/23C21D8/02C22C38/14C22C38/58
CPCB23K9/0216B23K9/23C21D8/0226C22C38/002C22C38/12C22C38/14C22C38/16C22C38/32C22C38/38
Inventor 半田恒久伊木聪远藤茂
Owner JFE STEEL CORP
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