Effects of C and Nb on Pore-Grain Boundary Separation Behavior during Sintering of 420 Stainless Steel
This study investigated the evolution of density, grain size, and pore characteristics during the sintering of metal injection molding (MIM) 420, 420 + 0.3C and pre-alloyed 420Nb stainless steel powders. The results show that C promotes the reduction of oxides on the surface of stainless steel, ther...
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MDPI AG
2022-07-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/12/7/1186 |
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| author | Tao Wen Hao He Jia Lou Mengqi Gan Xin Luo Yuhang Huang Wei Xu |
| author_facet | Tao Wen Hao He Jia Lou Mengqi Gan Xin Luo Yuhang Huang Wei Xu |
| author_sort | Tao Wen |
| collection | DOAJ |
| description | This study investigated the evolution of density, grain size, and pore characteristics during the sintering of metal injection molding (MIM) 420, 420 + 0.3C and pre-alloyed 420Nb stainless steel powders. The results show that C promotes the reduction of oxides on the surface of stainless steel, thereby accelerating sintering at 1330 °C, which is the initial sintering stage of MIM 420. MIM 420Nb showed the slowest sintering rate due to the strong binding force between Nb and C. At 1350 °C, the sintering densities of MIM 420 and 420 + 0.3C slightly improved, whereas their grain sizes grew significantly. Scanning electron microscopy images show grain boundary-pore separation, which significantly retarded the grain boundary diffusion mechanism and hence reduced the densification rate. The addition of C accelerated the pore-grain boundary separation; thus MIM 420 + 0.3C showed the lowest density at this temperature among the materials analyzed in this study. Nb suppressed the grain growth rate; thus, MIM 420Nb exhibited the highest density among the three materials. At 1370 °C, MIM 420 + 0.3C reached the highest density owing to the creation of a liquid phase. Theoretical calculations proved that there is a linear relationship between the grain boundary area per unit volume and the interfacial pore area per unit volume. Furthermore, when the ratio of grain size to pore size is 28, the contact probability between the grain boundaries and pores is significantly reduced to approximately 10%, leading to an extremely slow densification rate and a rapid grain growth rate, which is consistent with the experimental results. |
| first_indexed | 2024-03-09T06:12:33Z |
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| id | doaj.art-4f4e0024bdce4f51b52da26f4d3673c8 |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-09T06:12:33Z |
| publishDate | 2022-07-01 |
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| series | Metals |
| spelling | doaj.art-4f4e0024bdce4f51b52da26f4d3673c82023-12-03T11:56:40ZengMDPI AGMetals2075-47012022-07-01127118610.3390/met12071186Effects of C and Nb on Pore-Grain Boundary Separation Behavior during Sintering of 420 Stainless SteelTao Wen0Hao He1Jia Lou2Mengqi Gan3Xin Luo4Yuhang Huang5Wei Xu6School of Microelectronics and Materials Engineering, Guangxi University of Science and Technology, Liuzhou 545006, ChinaSchool of Microelectronics and Materials Engineering, Guangxi University of Science and Technology, Liuzhou 545006, ChinaSchool of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, ChinaSchool of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, ChinaSchool of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, ChinaSchool of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, ChinaThe Key Lab of Guangdong for Modern Surface Engineering Technology, National Engineering Laboratory for Modern Materials Surface Engineering Technology, Institute of New Materials, Guangdong Academy of Sciences, Guangzhou 510650, ChinaThis study investigated the evolution of density, grain size, and pore characteristics during the sintering of metal injection molding (MIM) 420, 420 + 0.3C and pre-alloyed 420Nb stainless steel powders. The results show that C promotes the reduction of oxides on the surface of stainless steel, thereby accelerating sintering at 1330 °C, which is the initial sintering stage of MIM 420. MIM 420Nb showed the slowest sintering rate due to the strong binding force between Nb and C. At 1350 °C, the sintering densities of MIM 420 and 420 + 0.3C slightly improved, whereas their grain sizes grew significantly. Scanning electron microscopy images show grain boundary-pore separation, which significantly retarded the grain boundary diffusion mechanism and hence reduced the densification rate. The addition of C accelerated the pore-grain boundary separation; thus MIM 420 + 0.3C showed the lowest density at this temperature among the materials analyzed in this study. Nb suppressed the grain growth rate; thus, MIM 420Nb exhibited the highest density among the three materials. At 1370 °C, MIM 420 + 0.3C reached the highest density owing to the creation of a liquid phase. Theoretical calculations proved that there is a linear relationship between the grain boundary area per unit volume and the interfacial pore area per unit volume. Furthermore, when the ratio of grain size to pore size is 28, the contact probability between the grain boundaries and pores is significantly reduced to approximately 10%, leading to an extremely slow densification rate and a rapid grain growth rate, which is consistent with the experimental results.https://www.mdpi.com/2075-4701/12/7/1186pore-grain boundary separationsinteringmetal injection molding420 stainless steeldensity |
| spellingShingle | Tao Wen Hao He Jia Lou Mengqi Gan Xin Luo Yuhang Huang Wei Xu Effects of C and Nb on Pore-Grain Boundary Separation Behavior during Sintering of 420 Stainless Steel Metals pore-grain boundary separation sintering metal injection molding 420 stainless steel density |
| title | Effects of C and Nb on Pore-Grain Boundary Separation Behavior during Sintering of 420 Stainless Steel |
| title_full | Effects of C and Nb on Pore-Grain Boundary Separation Behavior during Sintering of 420 Stainless Steel |
| title_fullStr | Effects of C and Nb on Pore-Grain Boundary Separation Behavior during Sintering of 420 Stainless Steel |
| title_full_unstemmed | Effects of C and Nb on Pore-Grain Boundary Separation Behavior during Sintering of 420 Stainless Steel |
| title_short | Effects of C and Nb on Pore-Grain Boundary Separation Behavior during Sintering of 420 Stainless Steel |
| title_sort | effects of c and nb on pore grain boundary separation behavior during sintering of 420 stainless steel |
| topic | pore-grain boundary separation sintering metal injection molding 420 stainless steel density |
| url | https://www.mdpi.com/2075-4701/12/7/1186 |
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