1992 Fiscal Year Final Research Report Summary
TWO-PHASE STAINLESS STEEL PRODUCED FROM MECHANICALLY MILLED METALLIC POWDER MIXTURE
| Project/Area Number |
03650581
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属材料(含表面処理・腐食防食)
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
TAKAI Setsuo KYUSHU UNIVERSITY,DEPARTMENT OF MATERIALS SCIENCE&ENGINEERING,ASSOCIATE PROFESSOR, 工学部, 助教授 (90150490)
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| Project Period (FY) |
1991 – 1992
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| Keywords | MECHANICAL MILLING / TRANSFORMATION / TWO-PHASE STAINLESS STEEL / WORK HARDENING / GRAIN REFINING / POWDER |
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| Research Abstract |
Powders of metallic iron,chromium and nickel was mixed and then mechanically milled in order to get Fe-25%Cr-8%Ni alloy through mechanical alloying(MA)process.Using the powder produced by the MA process,the consolidation of powder was tried and the phase decomposition mechanism was investigated by means of microstructural examinations.The results obtained were as follows:
(1)During milling treatment,solid-solutioning of Cr and Ni atoms takes place and homogeneous ferritic steel with the chemical composition of 25%Cr and 8%Ni was obtained after long milling treatment.
(2)When the particles of metallic Ni retained in the iron matrix,austenite phase grows from the Ni particles to form the equilibrium two phases of austenite and ferrite during annealing.In the homogeneous ferritic steel,however,the ferrite phase once allotropically transforms to full austenite owing to markedly increased strain,and then the austenite phase decompose to the equilibrium two phases.
(3)Metallic Cr particles retained within the matrix reacts with oxygen contained in iron powder and forms chromium oxide.Fine particles of chromium oxide play an important role for suppressing the grain growth of the two phases.
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