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Abrasion resistant steel plate which exhibits excellent weld toughness and excellent delayed fracture resistance

a technology of weld toughness and retarded fracture resistance, which is applied in the field of abrasion resistant steel plates or steel sheets, can solve the problems of delayed fractures, regions where toughness is remarkably deteriorated, so as to enhance manufacturing efficiency and safety, excellent toughness, and excellent retarded fracture resistance

Inactive Publication Date: 2013-08-15
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is about a way to make a steel plate that has good resistance to abrasion and delayed fracture. This method can increase efficiency and safety during the manufacturing process and make the steel structure stronger.

Problems solved by technology

However, in a weld, a bond area formed by a preceding weld pass is reheated by succeeding welding so that a region where toughness is remarkably deteriorated appears.
Particularly, in an abrasion resistant steel plate, when a bond area formed by welding for forming a first layer is reheated to a temperature around 300° C. due to succeeding welding, toughness is remarkably deteriorated due to low-temperature tempering embrittlement.
It has been pointed out that delayed fracture is liable to occur in a region which is reheated to such a low-temperature tempering embrittlement temperature.
Although patent document 5 studies weldability and abrasion resistant property of a weld, the study does not aim at the enhancement of weld toughness.
That is, the abrasion resistant steels proposed in patent documents 1 to 5 and the like are less than optimal with respect to the improvement of both weld toughness and delayed fracture resistance of a multi pass weld.

Method used

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  • Abrasion resistant steel plate which exhibits excellent weld toughness and excellent delayed fracture resistance
  • Abrasion resistant steel plate which exhibits excellent weld toughness and excellent delayed fracture resistance

Examples

Experimental program
Comparison scheme
Effect test

embodiment 1

[0065]Steel slabs which were prepared with various compositions shown in Table 1 by way of a steel converter, ladle refining and a continuous casting method were heated at a temperature of 1000 to 1250° C. and, thereafter, the steel slabs were subjected to hot rolling under manufacturing conditions shown in Table 2. Water cooling (quenching (DQ)) was applied to some steel plates after rolling. With respect to other steel plates, air cooling was performed after rolling, and water cooling (quenching (RQ)) was performed after reheating.

[0066]On the obtained steel plates, the surface hardness measurement, the evaluation of abrasion resistant property, the base material toughness measurement, a T shape fillet weld cracking test (evaluation of delayed fracture resistant property), a synthetic heat-affected zone test and a toughness test of a weld of an actual weld joint were carried out in accordance with following manners. The acquired result is shown in Table 3.

[Surface Hardness 1]

[0067...

embodiment 2

[0084]Steel slabs which were prepared with various compositions shown in Table 4 by way of a steel converter, ladle refining and a continuous casting method were heated at a temperature of 1000 to 1250° C. and, thereafter, the steel slabs were subjected to hot rolling under manufacturing conditions shown in Table 5. Water cooling (quenching (DQ)) is applied to some steel plates immediately after rolling. With respect to other steel plates, air cooling was applied to other steel plates after rolling, and water cooling (quenching (RQ)) was performed after reheating.

[0085]On the obtained steel plates, the surface hardness measurement, the evaluation of abrasion resistant property, the base material toughness measurement, a T shape fillet weld cracking test (evaluation of delayed fracture resistant property), a synthetic heat-affected zone test and a toughness test of a weld of an actual weld joint were carried out in accordance with following manners. The acquired result is shown in Ta...

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Abstract

An abrasion resistant steel plate which is excellent in toughness and delayed fracture resistance of a multi pass weld and is preferably used in construction machines, industrial machines and the like is provided. To be more specific, the composition of the steel plate contains by mass % 0.20 to 0.30% C, 0.05 to 1.0% Si, 0.40 to 1.2% Mn, 0.010% or less P, 0.005% or less S, 0.40 to 1.5% Cr, 0.005 to 0.025% Nb, 0.05 to 1.0% Mo, 0.005 to 0.03% Ti, 0.1% or less Al, 0.01% or less N, and 0.0003 to 0.0020% B, and further contains one, two or more kinds of components selected from a group consisting of W, Cu, Ni, V, REM, Ca and Mg when necessary, wherein DI* (DI*=33.85×(0.1×C)0.5×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3×Mo+1)×(1.75×V+1)×(1.5×W+1)) is 45 to 180, C+Mn / 4-Cr / 3+10P≦0.47, and a base phase of the microstructure is formed of martensite.

Description

TECHNICAL FIELD[0001]The present invention relates to an abrasion resistant steel plate or steel sheet having a plate thickness of 4 mm or more preferably used in construction machines, industrial machines, shipbuilding, steel pipes, civil engineering, architecture or the like, and more particularly to an abrasion resistant steel plate or steel sheet which exhibits excellent toughness and excellent delayed fracture resistance of a multi pass weld.BACKGROUND ART[0002]When a hot-roiled steel plate is employed for forming steel structural products, machines, devices or the like in construction machines, industrial machines, shipbuilding, steel pipes, civil engineering, architecture or the like, there may be a case where the steel plates are required to possess abrasion resistant property. Conventionally, to impart excellent abrasion resistant property to a steel material, hardness is increased in general, and hardness of the steel material can be remarkably enhanced by forming the stee...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/26C22C38/28C22C38/32C22C38/24C22C38/20C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C22C38/42C22C38/04C22C38/00C22C38/22
CPCC21D8/0226C22C38/06C22C38/02C22C38/04C22C38/22C22C38/26C22C38/28C22C38/32C22C38/54C22C38/005C22C38/002C22C38/48C22C38/46C22C38/50C22C38/42C22C38/24C22C38/20C22C38/44C22C38/001C21D8/0263
Inventor UEDA, KEIJISUZUKI, SHINICHI
Owner JFE STEEL CORP