Microstructural Refinement by Cu Addition and Its Effect on Strengthening and Toughening of Sour Service Line Pipe Steels

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概要

• 論文の詳細を見る

• The Mn content of sour service line pipe steels is desirable to be low because Mn forms the elongated MnS which acts as nucleation sites of hydrogen induced blister craking, and the segregation streak which provides the propagation path of the cracking. On the other hand, Mn is one of the most effective and economical alloying elements to strengthen and toughen. This study investigates the effect of Cu as an alternative to Mn to strengthen and toughen the line pipe steels containing low Mn. The Cu addition up to 1.7 mass% simultaneously increases yield strength and decreases Charpy transition temuperature, which effect of Cu is attributable to grain-refinement. However, the Cu addition over 2.0 mass% substantially raises the transition temperature with increasing the yield strength, which adverse effect is attributable to the precipitation of during cooling after hot rolling. Analyzing the results of the isothermal holding after hot deformation and the continuous cooling after hot deformation provides the mechanisms of the grain-refinement by solute Cu as follows. The solute Cu in austenite retards the recrystallization of hot deformed austenite, which retains more non-recrystallized austenite enhancing ferrite nucleation. Moreover, the solute Cu in austenite suppresses the austenite-ferrite transformation, which decreases the transformation temperature and thereby prevents formed ferrite grains from coarsening.

• 社団法人 日本鉄鋼協会の論文
• 1996-02-15

著者

• TAKAHASHI Akihiko

  Yawata R & D Laboratory, Nippon Steel Corporation

• Iino Makio

  Nippon Steel Corporation

関連論文

• Comparison between Full Scale Tests and Small Scale Tests in Evaluating the Cracking Susceptibility of Line Pipe in Sour Environment
• Influence of Softened Heat-affected Zone on Stress Oriented Hydrogen Induced Cracking of a High Strength Line Pipe Steel
• Influence of Microhardness and Inclusion on Stress Oriented Hydrogen Induced Cracking of Line Pipe Steels
• Improvement of Yield Strength-Transition Temperature Balance by Microstructural Refinement
• Microstructural Refinement by Cu Addition and Its Effect on Strengthening and Toughening of Sour Service Line Pipe Steels
• Thermo-mechanical Control Process as a Tool to Grain-refine the Low Manganese Containing Steel for Sour Service Line Pipe

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