Abrasion-resistant steel plate excellent in stress corrosion cracking resistance and manufacturing method thereof

Abstract

Provided is an abrasion resistant steel plate or steel sheet suitable for use in construction machines, industrial machines, and the like and a method for manufacturing the same. In particular, a steel plate or steel sheet excellent in resistance to stress corrosion cracking has a composition containing 0.20% to 0.30% C, 0.05% to 1.0% Si, 0.40% to 1.20% Mn, P, S, 0.1% or less Al, 0.01% or less N, and 0.0003% to 0.0030% B on a mass basis, the composition further containing one or more of Cr, Mo, and W, the composition further containing one or more of Nb, Ti, Cu, Ni, V, an REM, Ca, and Mg as required, the remainder being Fe and inevitable impurities. DI* due to contained components is 45 or more. A microstructure has a base phase or main phase that is tempered martensite. Cementite having a grain size of 0.05 µm or less in terms of equivalent circle diameter is present in the steel plate or steel sheet at 2 x 10 6 grains / mm 2 or more. A semi-finished product having the above steel composition is heated, hot rolling is performed, air cooling is performed, reheating is performed, and accelerated cooling is then performed or accelerated cooling is performed immediately after hot rolling.

Description

technical field [0001] The present invention relates to an abrasion resistant steel plate (abrasion resistant steel plate or steel sheet) with a plate thickness of 4 mm or more suitable for construction machines, industrial machines, shipbuilding, steel pipes, civil engineering, buildings, etc. It relates to a steel plate excellent in resistance of stress corrosion cracking (resistance of stress corrosion crack). Background technique [0002] When hot-rolled steel sheets are used in iron and steel structures, machines, devices, etc. of construction machinery, shipbuilding, steel pipes, civil engineering, and buildings, the abrasion resistance property of the steel sheet may be required. Abrasion is a phenomenon in which the surface of steel is scraped off due to continuous contact between steel materials or different types of materials such as sand, rocks, etc. [0003] If the wear resistance of steel materials is poor, not only will it cause failure of machinery and equipm...

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Problems solved by technology

[0003] If the wear resistance of the steel material is poor, it will not only cause failure of machinery and equipment, but also risk maintaining the strength of the structure, so frequent repairs and replacements of worn parts are unavoidable

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