| Project/Area Number |
60550511
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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 | Kyoto University |
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Principal Investigator |
MAKI Tadashi Kyoto University, Faculty of Engineering, Assoc Prof., 工学部, 助教授 (10026247)
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| Co-Investigator(Kenkyū-buntansha) |
TSUZAKI Kaneaki Kyoto University, Faculty of Engineering, Instructor., 工学部, 助手 (40179990)
UMEMOTO Minoru Kyoto University, Faculty of Engineering, Instructor., 工学部, 助手 (90111921)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | High-purity steel / Hardenabilty / Impurity element / Jominy test / Transformation kinetics / Growth rate / 核生成速度 |
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| Research Abstract |
The present study has been undertaken to make clear the effect of impurity elements such as P and S on hardenabilty and isothermal transformation behavior in high-purity carbon steels without other alloying elements excepted for carbon. Four 0.35% carbon steels with different level of P and S contents (i,e., 10 ppmP + 10 ppmS, 70 ppmP + 10 ppmS, 410 ppmP + 10 ppmS, and 10 ppmP + 100 ppmS) were vacuum-melted and used for the Jominy tests, the continuous transformation tests, and the isothermal transformation tests. The main results obtained are as follows.
(1) The Jominy distance increased with increase in the P content of specimen. The tendency of increase in the Jominy distance against the P content was parabolic, namely, the slope of the Jominy distance-the P content curve decreased with increase in the P content.
(2) The diffusional transformation which competes with martensite transformation and controlls the hardenabilty in the present steels was the pearlite transformation at around 820 K.
(3) The isothermal transformation kinetics from austenite to pearlite was markedly retarded by adding the impurity element of P as well as S.
(4) The addition of the impurity elements of P and S strongly reduced the growth rate of the pearlite colony at 823 K but scarcely affected the nucleation rate.
It can be concluded from these results that the hardenabilty increases by adding the impurity elements of P and S to high-purity 0.35% carbon steel and this increase in the hardenability is contributed to the decrease in the growth rate of the pearlite transformation which competes with the martensite transformation.
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