STEEL MATERIAL EXCELLENT IN TOUGHNESS IN HEAT AFFECTED ZONE, AND PRODUCTION METHOD OF STEEL MATERIAL EXCELLENT IN TOUGHNESS IN HEAT AFFECTED ZONE

• Main Authors: KIYOSE AKIHITO, YAMAUCHI HIROKI, FURUKAWA HIROTSUGU
• Format: Patent
• Language: English; Japanese
• Published: 03.08.2017
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; METALLURGY; METALLURGY OF IRON; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide a steel material excellent in toughness in a heat affected zone having further enhanced toughness in the heat affected zone by promoting transgranular ferrite transformation, and a production method of the steel material excellent in toughness of the heat affected zone.SOLUTION: The steel material excellent in toughness in a heat affected zone has a chemical component containing, by mass%, C, Si, Mn, P, S, Al, Ti, Mg, O and N in predetermined ranges and the balance Fe with inevitable impurities, and is characterized in that Ti particles each having a particle diameter of 0.01 μm or more and less than 0.5 μm and including oxide consisting of Mg and Al are present with the number density of 10000/mmand Mg-containing oxide particles each having a particle diameter of 0.5 μm to 5 μm and containing Mg of 50% by mass% are present with the number density of 50/mmor more.SELECTED DRAWING: None 【課題】粒内フェライト変態を促進させることにより溶接熱影響部の靭性をさらに向上させた溶接熱影響部の靭性に優れた鋼材、及び、溶接熱影響部の靭性に優れた鋼材の製造方法を提供する。【解決手段】質量％で、Ｃ、Ｓｉ、Ｍｎ、Ｐ、Ｓ、Ａｌ、Ｔｉ、Ｍｇ、Ｏ、Ｎを所定の範囲内で含有し、残部がＦｅ及び不可避的不純物からなる化学成分を有し、ＭｇとＡｌからなる酸化物を内包する粒径０．０１μｍ以上０．５μｍ未満のＴｉＮ粒子が、１００００個／ｍｍ２以上の個数密度で存在するとともに、Ｍｇを質量％で５０％以上含む粒径０．５μｍ以上５μｍ以下のＭｇ含有酸化物粒子が、５０個／ｍｍ２以上の個数密度で存在することを特徴とする。【選択図】なし