Electron-beam welded joint, steel material for electron-beam welding, and manufacturing method therefor

Abstract

A steel material for electron-beam welding, said steel material containing, by mass, at least the following: 0.02-0.10% carbon, 0.03-0.30% silicon, 1.5-2.5% manganese, 0.005-0.015% titanium, 0.0020-0.0060% nitrogen, and 0.0010-0.0035% oxygen. The amounts of sulfur, phosphorus, and aluminum in said steel material are limited to at most 0.010%, at most 0.015%, and at most 0.004% by mass, respectively, with the remainder of said steel material comprising iron and unavoidable impurities. Said steel material has an index (CeEBB) of 0.42% to 0.65%, and in the thicknesswise middle of a cross-section of said steel material parallel to the thickness direction of the steel material, the number of oxides having equivalent circular diameters of at least 1.0 [mu]m is at most 20 per square millimeter and the number of oxides that contain at least 10% titanium and have equivalent circular diameters of at least 0.05 [mu]m and less than 0.5 [mu]m is 103 to 105 per square millimeter.

Description

technical field [0001] The present invention relates to a steel material for electron beam welding and a manufacturing method thereof. The steel material for electron beam welding is used for welding by irradiating an electron beam to a welded area sandwiched by a plate-shaped or foil-shaped embedded metal on a groove surface, and further relates to a An electron beam welded joint formed by irradiating electron beams to the welded area sandwiching the embedded metal between the groove surfaces of the steel. [0002] This application is based on Japanese Patent Application Japanese Patent Application No. 2010-260458 for which it applied on November 22, 2010, and the priority is claimed, and uses the content here. Background technique [0003] In recent years, in order to reduce CO2 gas, which is one of the causes of the global environment's greenhouse effect, and to cope with the future depletion of fossil fuels such as petroleum, active attempts have been made to utilize ren...

AI Technical Summary

Problems solved by technology

Since the size of the test piece affects the fracture toughness, good results can be obtained even in small tests such as the conventional V-notch Charpy impact test, but in the CTOD test of welded joints of large steel structures, It may not be possible to obtain a good fracture toughness value δc

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