1996 Fiscal Year Final Research Report Summary
RESEARCH AND DEVELOPMENT OF NEW ROLL MATERIALS WITH MULTI-COMPONENT SYSTEM
| Project/Area Number |
06555223
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 試験 |
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| Research Field |
Metal making engineering
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| Research Institution | KURUME NATIONAL COLLEGE OF TECHNOLOGY |
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Principal Investigator |
MATSUBARA Yasuhiro KURUME NATIONAL COLLEGE OF TECH., MAT.SCI.& MET.ENG., PROFESSOR, 材料工学科, 教授 (20044258)
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| Co-Investigator(Kenkyū-buntansha) |
HONDA Yoshioki KURUME NATIONAL COLLEGE OF TECH., MAT.SCI.& MET.ENG., ASSO.PROF., 材料工学科, 助教授 (10044281)
SASAGURI Nobuya KURUME NATIONAL COLLEGE OF TECH., MAT.SCI.& MET.ENG., ASSO.PROF., 材料工学科, 助教授 (50215737)
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| Project Period (FY) |
1994 – 1996
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| Keywords | Multi-component Alloy / Roll Materirals / Carbide Morphology / Solidiffication Process / CCT Curve / Tungsten Equivalent (W_<eq>) |
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| Research Abstract |
The purpose of this research project is to research and develop the new roll materials with high wear resistance and performance for rolling and pulverizing mills using multi-component alloys. The type of carbide precipitaion in multi-component alloys are MC,M_2C,M_7C_3 and M_3C.Morphology of the MC carbide is classified into three of petal-like, nodular and coral-like types. The M_2C carbide is classified into two of lamellar and coarse plate-like types, and the morphology of M_7C_3 is rod-like or ledeburitic types. The type and morphology of carbides varied remarkably depending on chemical compossition of alloy, particularly C and V,and Mo and W expressed by a parameter of tungsten equivalent (W_<eq>), when Cr and Co contents are constant. However, they are not changed by cobalt. Region of chemical compositions in which each type of carbide precipitates is expressed by simple equations in relation to the contents of C vs. V and W_<eq>.
Solidification of the alloy with MC and M_2C eute
… More
ctic carbides takes the following process ; austenite (gamma) phase or MC carbide precipitates firstly as a primary phase, then L*gamma+MC eutectic reaction occurs and the solidification finishes the eutectic reaction of L*gamma+M_2C.In the alloy where MC and M_7C_3 carbides coexist, the solidification begins with precititation of primary gamma phase or MC carbide, followed by the L*gamma+MC eutectic reaction, and finally the L*gamma+M_7C_3 eutectic reaction. As for the alloy with MC,M_7C_3 and M_2C eutectic carbides, the solidification sequence is as follows ; L_0*gamma+MC+(L_1), L_1*gamma+M_7C_3+(L_2) and L_2*gamma+M_2C.
The continuous cooling transformation (CCT) curve of the multi-component alloy was found to consist of two curves of pearlite and bainite transformations separated far about 200K betweem them. The positions of both transformation curves are largely changed by the chemical composition and austenitizing temperature.
By selecting a combination of alloying elements, therefore, the multi-component alloys with different matrix structures can be obtained. Generally, an increase in C content delays the pearlite transformation and advances the bainite transformation and lowers the M_S temperatures. Higher austenitizing temperature shifts CCT curve to the long time side and this improves the hardenability of the alloy.
Co decreases the hardenability of multi-component alloy because Co promotes both of the pearlite and banite transformation. However, Co does not reduces the M_S temperature so much. V delays both of pearlite and banite transformation and the delaying degree of the pearlite transformation is more than the bainite transformation.
In the case of heat treatment of these alloys, the secondary precipitation hardening occurs greatly by tempering at around 800K,and there the retained austenite reduces almost less than 3%. The maximum hardness obtained by the secondary hardening ranges from HV 900 to HV 1050. It is made clear that the increase in C and V contents and the austenitizing temperature must increase the tempering tempering temperature to obtain the maximum hardness. Less
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Research Products
(4 results)
