In this study, two types of SKD61 tool-steel samples are built by a selective laser melting (SLM) process using the different laser scan speeds. The characteristics of two kinds of SKD61 tool-steel powders used in the SLM process are evaluated. Commercial SKD61 tool-steel power has a flowability of 16.68 sec/50 g and its Hausner ratio is calculated to be 1.25 by apparent and tapped density. Also, the fabricated SKD61 tool steel powder fabricated by a gas atomization process has a flowability of 21.3 sec/50 g and its Hausner ratio is calculated to be 1.18. Therefore, we confirmed that the two powders used in this study have excellent flowability. Samples are fabricated to measure mechanical properties. The highest densities of the SKD61 tool-steel samples, fabricated under the same conditions, are 7.734 g/cm³ (using commercial SKD61 powder) and 7.652 g/cm3 (using fabricated SKD61 powder), measured with Archimedes method. Hardness is measured by Rockwell hardness testing equipment 5 times and the highest hardnesses of the samples are 54.56 HRC (commercial powder) and 52.62 HRC (fabricated powder). Also, the measured tensile strengths are approximately 1,721 MPa (commercial SKD61 powder) and 1,552 MPa (fabricated SKD61 powder), respectively.

Abstract
 1. 서 론
 2. 실험 방법
 3. 결과 및 고찰
 4. 결 론
 References

• 윤재철(한국기계연구원 부설 재료연구소, 분말/세라믹연구본부) | Jaecheol Yun
• 최중호(한국기계연구원 부설 재료연구소, 분말/세라믹연구본부) | Jungho Choe
• 김기봉(한국기계연구원 부설 재료연구소, 분말/세라믹연구본부) | Ki-Bong Kim
• 양상선(한국기계연구원 부설 재료연구소, 분말/세라믹연구본부) | Sangsun Yang
• 양동열(한국기계연구원 부설 재료연구소, 분말/세라믹연구본부, 한국기계연구원, M3P 융합연구단) | Dong-Yeol Yang
• 김용진(한국기계연구원 부설 재료연구소, 분말/세라믹연구본부) | Yong-Jin Kim
• 이창우(한국기계연구원, M3P 융합연구단) | Chang-Woo Lee
• 유지훈(한국기계연구원 부설 재료연구소, 분말/세라믹연구본부, 한국기계연구원, M3P 융합연구단) | Ji-Hun Yu Corresponding Author