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■■■■■■■■■■■■■■■■■■■ 川崎製鉄技報 KAWASAKI STEEL GIHO Vol.15 (1983) No.1 ■■■■■■■■■■■■■■■■■■■ |
| 低温用厚肉3 1/2Ni鋳鋼の機械的性質 Mechanical Properties of Heavy Walled 3 1/2 Ni Steel Castings for Low Temperature Service 野口 紘(Hiroshi Noguchi) 土平 純一(Jun-ichi Tsuchihira) 萩原 等(Hitoshi Hagiwara) 大野 勝信(Katsunobu Ohno) 松野 淳一(Jun-ichi Matsuno) 田中 智夫(Tomoo Tanaka) |
| 要旨 : 氷海域で使用可能な厚肉3 1/2 Ni鋳鋼の開発を目的として実験室的に成分及び熱処理条件を検討した。その結果，低C-中Si-高Mn-0.2Mo系3 1/2Ni鋳鋼とし，熱処理条件として３段階の繰返し焼ならし後焼もどしすれば，強度・じん性の優れた低温用鋳鋼が得られることがわかった。この結果にもとづき，500mm厚鋳鋼試験材（重量4.6t）を鋳込み，熱処理したあと断面各部の機械的性質を調査した。断面各部で若干の差はあるものの，強度・じん性ともASTM A757-B3N鋳鋼（衝撃試験温度-101℃）の規格をほぼ満たし，肉厚500mm以下の当鋼種鋳鋼品は氷海域で十分使用可能であることがわかった。 |
| Synopsis : For the purpose of developing thick 3.5 Ni cast steel applicable to arctic use, its chemical composition and heat-treating conditions were investigated o laboratory and commercial scales. Low carbon-medium silicon-0.2 molybdenum-3.5 nickel cast steel was found to be of the optimum chemistry for improving both strength and toughness. Three cycles of normalizing followed by tempering instead of single normalizing and tempering were found to improve markedly the low temperature toughness of the cast steel. On the basis of the laboratory test results, 500mm thick steel ingot by weight of 4.6t was cast, heat-treated and subjected to testing at its various locations. Though there was a slight difference in properties depending on the locations, the tensile and impact properties of the present cast steel met the requirements of ASTM A757-B3N cast steel whose impact toughness is specified at -101℃. So far as its thickness is less than 500mm, the newly developed cast steel is found to be applicable to arctic use. |
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