냉간금형용 합금공구강 분말 및 적층조형체의 미세조직
Microstructures of Powders and Additively Manufactured Objects of an Alloy Tool Steel for Cold-Work Dies
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A cold-work tool steel powder is used to fabricate 3-dimensional objects by selective laser melting using a high-pressure gas atomization process. The spherical powder particles form continuous carbide networks among the austenite matrix and its decomposition products. The carbides comprise Nb-rich MC and Mo-rich M2C. In the SLM process, the process parameters such as the laser power (90 W), layer thickness (25 μm), and hatch spacing (80 μm) are kept fixed, while the scan speed is changed from 50 mm/s to 4000 mm/s. At a low scan speed of 50 mm/s, spherical cavities develop due to over melting, while they are substantially reduced on increasing the speed to 2000 mm/s. The carbide network spacing decreases with increasing speed. At an excessively high speed of 4000 mm/s, long and irregularly shaped cavities are developed due to incomplete melting. The influence of the scan pattern is examined, for which 1 × 1 mm2 blocks constituting a processing layer are irradiated in a random sequence. This island-type pattern exhibits the same effect as that of a low scan speed. Post processing of an object using hot isostatic pressing leads to a great reduction in the porosity but causes coarsening of the microstructure.
Abstract
A cold-work tool steel powder is used to fabricate 3-dimensional objects by selective laser melting using a high-pressure gas atomization process. The spherical powder particles form continuous carbide networks among the austenite matrix and its decomposition products. The carbides comprise Nb-rich MC and Mo-rich M2C. In the SLM process, the process parameters such as the laser power (90 W), layer thickness (25 μm), and hatch spacing (80 μm) are kept fixed, while the scan speed is changed from 50 mm/s to 4000 mm/s. At a low scan speed of 50 mm/s, spherical cavities develop due to over melting, while they are substantially reduced on increasing the speed to 2000 mm/s. The carbide network spacing decreases with increasing speed. At an excessively high speed of 4000 mm/s, long and irregularly shaped cavities are developed due to incomplete melting. The influence of the scan pattern is examined, for which 1 × 1 mm2 blocks constituting a processing layer are irradiated in a random sequence. This island-type pattern exhibits the same effect as that of a low scan speed. Post processing of an object using hot isostatic pressing leads to a great reduction in the porosity but causes coarsening of the microstructure.
참고문헌 (31)
- "ISO", ASTM 52900, ASTM Inter., pp.2016, ~
- D. L. Bourell, , Annu. Rev. Mater. Res., 46, pp.1~ (2016)
- L. E. Murr, , J. Mater. Sci. Tech., 32, pp.987~ (2016)
- W. E. Frazier, , JMEPEG, 23, pp.1917~ (2014)
- S. Singh, , J. Manuf. Process., 25, pp.185~ (2017)
- C.W. Hull, "US 4575330", ~ (1984)
- "3D Systems"[URL]
- "J. H. Kim", KISTI, 3~, pp.KISTI Mark. Rep., 4-3 (2014)
- D. G. Ahn, , J. KSME, 54(4), pp.46~ (2014)
- A. J. Pinkerton, , Int. J. Adv. Manuf. Technol., 25, pp.471~ (2005)
- J. Y. Chen, , Mater. Sci. Eng. A, 527, pp.7265~ (2010)
- L. Xue, , Metallogr. Microstruct. Anal., 2, pp.67~ (2013)
- R. Cottam, , J. Mater. Res., 29, pp.1978~ (2014)
- L. Xue, , Metallogr. Microstruct. Anal., 2, pp.67~ (2013)
- 강전연, "매트릭스(matrix)형 냉간금형강의 기계적 특성에 미치는 NbC 탄화물 첨가의 영향", 열처리공학회지, 28(5), pp.239~249 (2015), 한국열처리공학회
- J. -Y. Kang, "KR 10-2016-0095794", ~ (2016)
- J. -Y. Kang, , Scr. Mater., 102, pp.63~ (2015)
- H. Kim, , Mater. Charac., 107, pp.376~ (2015)
- R. O. Elliott, , J. Phys. Chem., 62, pp.630~ (1958)
- T. Epicier, , Acta Metall, 36, pp.1903~ (1988)
- J. O. Anderson, , Calphad, 26, pp.273~ (2002)
- "Thermo-Calc Software TCFE7 Steels", Fe-alloys database version 7
- G. H. Gulliver, , J. Inst. Met., 9, pp.120~ (1913)
- E. Scheil, "Bemerkungen zur schichtkristallbildung", Z. Metallkd., 34, pp.70~ (1942)
- Å. Jansson, "Simulation of solidification of light alloys using a thermodynamicdatabase" (1997), KTH
- J. P. Kruth, , J. Mater. Proc. Tech., 149, pp.616~ (2004)
- H. Gong, , Additive Manuf., 1-4, pp.87~ (2014)
- M. Sadowski, , Additive Manuf, 11, pp.60~ (2016)
- T. Heeling, , Additive Manuf., 14, pp.116~ (2017)
- M. Courtois, , J. Phys. D: Appl. Phys., 46, pp.505305~ (2013)
- W. Tillmann, , Additive Manuf., 13, pp.93~ (2017)