Fig. 1. Schematic of (a) geometry of the simulation model, (b) A-A cross-section presenting the locations of point probes for recording temperature history (unit: µm).

17-4 PH 스테인리스강의 레이저 분말 베드 융합: 열처리가 미세조직의 진화 및 기계적 특성에 미치는 영향에 대한 비교 연구

panelS.Saboonia, A.Chaboka, S.Fenga,e, H.Blaauwb, T.C.Pijperb,c, H.J.Yangd, Y.T.Peia
aDepartment of Advanced Production Engineering, Engineering and Technology Institute Groningen, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
bPhilips Personal Care, Oliemolenstraat 5, 9203 ZN, Drachten, The Netherlands
cInnovation Cluster Drachten, Nipkowlaan 5, 9207 JA, Drachten, The Netherlands
dShi-changxu Innovation Center for Advanced Materials, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, P. R. China
eSchool of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083, P.R. China

Abstract

17-4 PH (precipitation hardening) stainless steel is commonly used for the fabrication of complicated molds with conformal cooling channels using laser powder bed fusion process (L-PBF). However, their microstructure in the as-printed condition varies notably with the chemical composition of the feedstock powder, resulting in different age-hardening behavior. In the present investigation, 17-4 PH stainless steel components were fabricated by L-PBF from two different feedstock powders, and subsequently subjected to different combinations of post-process heat treatments. It was observed that the microstructure in as-printed conditions could be almost fully martensitic or ferritic, depending on the ratio of Creq/Nieq of the feedstock powder. Aging treatment at 480 °C improved the yield and ultimate tensile strengths of the as-printed components. However, specimens with martensitic structures exhibited accelerated age-hardening response compared with the ferritic specimens due to the higher lattice distortion and dislocation accumulation, resulting in the “dislocation pipe diffusion mechanism”. It was also found that the martensitic structures were highly susceptible to the formation of reverted austenite during direct aging treatment, where 19.5% of austenite phase appeared in the microstructure after 15 h of direct aging. Higher fractions of reverted austenite activates the transformation induced plasticity and improves the ductility of heat treated specimens. The results of the present study can be used to tailor the microstructure of the L-PBF printed 17-4 PH stainless steel by post-process heat treatments to achieve a good combination of mechanical properties.

17-4 PH(석출 경화) 스테인리스강은 레이저 분말 베드 융합 공정(L-PBF)을 사용하여 등각 냉각 채널이 있는 복잡한 금형 제작에 일반적으로 사용됩니다. 그러나 인쇄된 상태의 미세 구조는 공급원료 분말의 화학적 조성에 따라 크게 달라지므로 시효 경화 거동이 다릅니다.

현재 조사에서 17-4 PH 스테인리스강 구성요소는 L-PBF에 의해 두 가지 다른 공급원료 분말로 제조되었으며, 이후에 다양한 조합의 후처리 열처리를 거쳤습니다. 인쇄된 상태의 미세구조는 공급원료 분말의 Creq/Nieq 비율에 따라 거의 완전히 마르텐사이트 또는 페라이트인 것으로 관찰되었습니다.

480 °C에서 노화 처리는 인쇄된 구성 요소의 수율과 극한 인장 강도를 개선했습니다. 그러나 마텐자이트 구조의 시편은 격자 변형 및 전위 축적이 높아 페라이트 시편에 비해 시효 경화 반응이 가속화되어 “전위 파이프 확산 메커니즘”이 발생합니다.

또한 마르텐사이트 구조는 직접 시효 처리 중에 복귀된 오스테나이트의 형성에 매우 민감한 것으로 밝혀졌으며, 여기서 15시간의 직접 시효 후 미세 조직에 19.5%의 오스테나이트 상이 나타났습니다.

복귀된 오스테나이트의 비율이 높을수록 변형 유도 가소성이 활성화되고 열처리된 시편의 연성이 향상됩니다. 본 연구의 결과는 기계적 특성의 우수한 조합을 달성하기 위해 후처리 열처리를 통해 L-PBF로 인쇄된 17-4 PH 스테인리스강의 미세 구조를 조정하는 데 사용할 수 있습니다.

Keywords

Laser powder bed fusion17-4 PH stainless steelPost-process heat treatmentAge hardeningReverted austenite

Fig. 1. Schematic of (a) geometry of the simulation model, (b) A-A cross-section presenting the locations of point probes for recording temperature history (unit: µm).
Fig. 1. Schematic of (a) geometry of the simulation model, (b) A-A cross-section presenting the locations of point probes for recording temperature history (unit: µm).
Fig. 2. Optical (a, b) and TEM (c) micrographs of the wrought 17-4 PH stainless steel.
Fig. 2. Optical (a, b) and TEM (c) micrographs of the wrought 17-4 PH stainless steel.
Fig. 3. EBSD micrographs of the as-printed 17-4 PH steel fabricated with “powder A” (a, b) and “powder B” (c, d) on two different cross sections: (a, c) perpendicular to the building direction, and (b, d) parallel to the building direction.
Fig. 3. EBSD micrographs of the as-printed 17-4 PH steel fabricated with “powder A” (a, b) and “powder B” (c, d) on two different cross sections: (a, c) perpendicular to the building direction, and (b, d) parallel to the building direction.
Fig. 4. Microstructure of the as-printed 17-4 PH stainless steel fabricated with “powder A” (a) and “powder B” (b).
Fig. 4. Microstructure of the as-printed 17-4 PH stainless steel fabricated with “powder A” (a) and “powder B” (b).
Fig. 5. Simulated temperature history of the probes located at the cross section of the L-PBF 17-4 PH steel sample.
Fig. 5. Simulated temperature history of the probes located at the cross section of the L-PBF 17-4 PH steel sample.
Fig. 6. Dependency of the volume fraction of delta ferrite in the final microstructure of L-PBF printed 17-4 PH steel as a function of Creq/Nieq.
Fig. 6. Dependency of the volume fraction of delta ferrite in the final microstructure of L-PBF printed 17-4 PH steel as a function of Creq/Nieq.
Fig. 7. IQ + IPF (left column), parent austenite grain maps (middle column) and phase maps (right column, green color = martensite, red color = austenite) of the post-process heat treated 17-4 PH stainless steel: (a-c) direct aged, (d-f) HIP + aging, (g-i) SA + Aging, and (j-l) HIP + SA + aging (all sample were printed with “powder A”).
Fig. 7. IQ + IPF (left column), parent austenite grain maps (middle column) and phase maps (right column, green color = martensite, red color = austenite) of the post-process heat treated 17-4 PH stainless steel: (a-c) direct aged, (d-f) HIP + aging, (g-i) SA + Aging, and (j-l) HIP + SA + aging (all sample were printed with “powder A”).
Fig. 8. TEM micrographs of the post process heat treated 17-4 PH stainless steel: (a) direct aging and (b) HIP + aging (printed with “powder A”).
Fig. 8. TEM micrographs of the post process heat treated 17-4 PH stainless steel: (a) direct aging and (b) HIP + aging (printed with “powder A”).
Fig. 9. XRD patterns of the post-process heat treated 17-4 PH stainless steel printed with “powder A”.
Fig. 9. XRD patterns of the post-process heat treated 17-4 PH stainless steel printed with “powder A”.
Fig. 10. (a) Volume fraction of reverted austenite as a function of aging time for “direct aging” condition, (b) phase map (green color = martensite, red color = austenite) of the 15 h direct aged specimen printed with “powder A”.
Fig. 10. (a) Volume fraction of reverted austenite as a function of aging time for “direct aging” condition, (b) phase map (green color = martensite, red color = austenite) of the 15 h direct aged specimen printed with “powder A”.
Fig. 11. Microhardness variations of the “direct aged” specimens as a function of aging time at 480 °C.
Fig. 11. Microhardness variations of the “direct aged” specimens as a function of aging time at 480 °C.
Fig. 12. Kernel average misorientation graphs of the as-printed 17-4 PH steel with (a) martensitic structure (printed with “powder A”) and (b) ferritic structure (printed with “powder b”).
Fig. 12. Kernel average misorientation graphs of the as-printed 17-4 PH steel with (a) martensitic structure (printed with “powder A”) and (b) ferritic structure (printed with “powder b”).
Fig. 13. Typical stress-strain curves (a) along with the yield and ultimate tensile strengths (b) and elongation (c) of the as-printed and post-process heat treated 17-4 PH stainless steel (all sample are fabricated with “powder A”).
Fig. 13. Typical stress-strain curves (a) along with the yield and ultimate tensile strengths (b) and elongation (c) of the as-printed and post-process heat treated 17-4 PH stainless steel (all sample are fabricated with “powder A”).
Fig. 14. (a) IQ + IPF and (b) phase map (green color = martensite, red color = austenite) of the “direct aged” specimen after tensile test at a location nearby the rupture point (tension direction from left to right).
Fig. 14. (a) IQ + IPF and (b) phase map (green color = martensite, red color = austenite) of the “direct aged” specimen after tensile test at a location nearby the rupture point (tension direction from left to right).

References

[1]

P. Bajaj, A. Hariharan, A. Kini, P. Kürnsteiner, D. Raabe, E.A. Jagle

Steels in additive manufacturing: A review of their microstructure and properties

Materials Science and Engineering: A, 772 (2020), Article 138633

ArticleDownload PDFView Record in ScopusGoogle Scholar

[2]

Y. Sun, R.J. Hebert, M. Aindow

Effect of heat treatments on microstructural evolution of additively manufactured and wrought 17-4PH stainless steel

Mater. Des., 156 (2018), pp. 429-440

ArticleDownload PDFView Record in ScopusGoogle Scholar

[3]

Zemin Wang, Xulei Fang, Hui Li, Wenqing Liu

Atom Probe Tomographic Characterization of nanoscale cu-rich Precipitates in 17-4 precipitate hardened stainless steel tempered at different temperatures

Microsc. Microanal., 23 (2017), pp. 340-349

View Record in ScopusGoogle Scholar

[4]

C.N. Hsiao, C.S. Chiou, J.R. Yang

Aging reactions in a 17-4 PH stainless steel

Mater. Chem. Phys., 74 (2002), pp. 134-142

ArticleDownload PDFView Record in ScopusGoogle Scholar

[5]

Hamidreza Riazi, Fakhreddin Ashrafizadeh, Sayed Rahman Hosseini, Reza Ghomashchi

Influence of simultaneous aging and plasma nitriding on fatigue performance of 17-4 PH stainless steel

Mater. Sci. Eng. A, 703 (2017), pp. 262-269

ArticleDownload PDFView Record in ScopusGoogle Scholar

[6]

M.S. Shinde, K.M. Ashtankar

Additive manufacturing–assisted conformal cooling channels in mold manufacturing processes

Adv. Mech. Eng., 9 (2017), pp. 1-14

View Record in ScopusGoogle Scholar

[7]

A. Armillotta, R. Baraggi, S. Fasoli

SLM tooling for die casting with conformal cooling channels

Int. J. Adv. Manuf. Technol., 71 (2014), pp. 573-583

CrossRefView Record in ScopusGoogle Scholar

[8]

Amar M. Kamat, Yutao Pei

An analytical method to predict and compensate for residual stress-induced deformation in overhanging regions of internal channels fabricated using powder bed fusion

Additive Manufacturing, 29 (2019), Article 100796

ArticleDownload PDFView Record in ScopusGoogle Scholar

[9]

K.S. Prakash, T. Nancharaih, V.V. Subba Rao

Additive Manufacturing Techniques in Manufacturing – An Overview

Materials Today: Proceedings, 5 (2018), pp. 3873-3882

ArticleDownload PDFView Record in ScopusGoogle Scholar

[10]

R. Singh, A. Gupta, O. Tripathi, S. Srivastava, B. Singh, A. Awasthi, S.K. Rajput, P. Sonia, P. Singhal, K.K. Saxena

Powder bed fusion process in additive manufacturing: An overview

Materials Today: Proceedings, 26 (2020), pp. 3058-3070

ArticleDownload PDFGoogle Scholar

[11]

L. Zai, Ch Zhang, Y. Wang, W. Guo, D. Wellmann, X. Tong, Y. Tian

Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review

Metals, 10 (2020), p. 255

CrossRefView Record in ScopusGoogle Scholar

[12]

H. Khalid Rafi, Deepankar Pal, Nachiket Patil, Thomas L. Starr, Brent E. Stucker

Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

J. Mater. Eng. Perf, 23 (2014), pp. 4421-4428

Google Scholar

[13]

A. Yadollahi, N. Shamsaei, S.M. Thompson, A. Elwany, L. Bian

Effects of building orientation and heat treatment on fatigue behavior of selective laser melted 17-4 PH stainless steel

Int. J. Fatigue, 94 (2017), pp. 218-235

ArticleDownload PDFView Record in ScopusGoogle Scholar

[14]

M. Alnajjar, Frederic Christien, Cedric Bosch, Krzysztof Wolski

A comparative study of microstructure and hydrogen embrittlement of selective laser melted and wrought 17–4 PH stainless steel

Materials Science and Engineering: A, 785 (2020), Article 139363

ArticleDownload PDFView Record in ScopusGoogle Scholar

[15]

M. Alnajjar, F. Christien, K. Wolski, C. Bosch

Evidence of austenite by-passing in a stainless steel obtained from laser melting additive manufacturing

Addit. Manuf, 25 (2019), pp. 187-195

ArticleDownload PDFView Record in ScopusGoogle Scholar

[16]

P.D. Nezhadfar, K. Anderson-Wedge, S.R. Daniewicz, N. Phan, Sh Shao, N. Shamsaei

Improved high cycle fatigue performance of additively manufactured 17-4 PH stainless steel via in-process refining micro-/defect-structure

Additive Manufacturing, 36 (2020), Article 101604

ArticleDownload PDFView Record in ScopusGoogle Scholar

[17]

S. Feng, A.M. Kamat, S. Sabooni, Y. Pei

Experimental and numerical investigation of the origin of surface roughness in laser powder bed fused overhang regions

Virtual and Physical Prototyping, 16 (2021), pp. S66-S84, 10.1080/17452759.2021.1896970

CrossRefView Record in ScopusGoogle Scholar

[18]

W. Liu, J. Ma, M. Mazar Atabaki, R. Pillai, B. Kumar, U. Vasudevan, H. Sreshta, R. Kovacevic

Hybrid Laser-arc Welding of 17-4 PH Martensitic Stainless Steel

Lasers in Manufacturing and Materials Processing, 2 (2015), pp. 74-90

CrossRefView Record in ScopusGoogle Scholar

[19]

J.C. Lippold, D.J. Kotecki

Welding metallurgy and weldability of stainless steels

Wiley (2005)

Google Scholar

[20]

M. Shirdel, H. Mirzadeh, M.H. Parsa

Nano/ultrafine grained austenitic stainless steel through the formation and reversion of deformation-induced martensite: Mechanisms, microstructures, mechanical properties, and TRIP effect

Mater. Charact., 103 (2015), pp. 150-161

ArticleDownload PDFView Record in ScopusGoogle Scholar

[21]

S. Kou

Solidification and liquation cracking issues in welding

JOM, 55 (2003), pp. 37-42

CrossRefView Record in ScopusGoogle Scholar

[22]

T.J. Lienert, J.C. Lippold

Improved Weldability Diagram for Pulsed Laser Welded Austenitic Stainless Steels

Sci. Technol. Weld. Join., 8 (2003), pp. 1-9

CrossRefView Record in ScopusGoogle Scholar

[23]

Ch Qiu, M. Al Kindi, A.S. Aladawi, I. Al Hatmi

A comprehensive study on microstructure and tensile behaviour of a selectively laser melted stainless steel

Sci. Rep., 8 (2018), p. 7785

View Record in ScopusGoogle Scholar

[24]

P.A. Hooper

Melt pool temperature and cooling rates in laser powder bed fusion

Addit. Manuf, 22 (2018), pp. 548-559

ArticleDownload PDFView Record in ScopusGoogle Scholar

[25]

T. DebRoy, H.L. Wei, J.S. Zuback, T. Mukherjee, J.W. Elmer, J.O. Milewski, A.M. Beese, A. Wilson-Heid, A. Ded, W. Zhang

Additive manufacturing of metallic components – Process, structure and properties

Prog. Mater. Sci., 92 (2018), pp. 112-224

ArticleDownload PDFView Record in ScopusGoogle Scholar

[26]

S. Vunnam, A. Saboo, Ch Sudbrack, T.L. Starr

Effect of powder chemical composition on the as-built microstructure of 17- 4 PH stainless steel processed by selective laser melting

Additive Manufacturing, 30 (2019), Article 100876

ArticleDownload PDFView Record in ScopusGoogle Scholar

[27]

L. Couturier, F. De Geuser, M. Descoins, A. Deschamps

Evolution of the microstructure of a 15-5PH martensitic stainless steel during precipitation hardening heat treatment

Mater. Des., 107 (2016), pp. 416-425

ArticleDownload PDFView Record in ScopusGoogle Scholar

[28]

C. Cayron, B. Artaud, L. Briottet

Reconstruction of parent grains from EBSD data

Mater. Charact., 57 (2006), pp. 386-401

ArticleDownload PDFView Record in ScopusGoogle Scholar

[29]

R. Bhambroo, S. Roychowdhury, V. Kain, V.S. Raja

Effect of reverted austenite on mechanical properties of precipitation hardenable 17-4 stainless steel

Mater. Sci. Eng. A, 568 (2013), pp. 127-133

ArticleDownload PDFView Record in ScopusGoogle Scholar

[30]

T. LeBrun, T. Nakamoto, K. Horikawa, H. Kobayashi

Effect of retained austenite on subsequent thermal processing and resultant mechanical properties of selective laser melted 17–4 PH stainless steel

Mater. Des., 81 (2015), pp. 44-53

ArticleDownload PDFView Record in ScopusGoogle Scholar

[31]

T.H. Hsu, Y.J. Chang, C.Y. Huang, H.W. Yen, C.P. Chen, K.K. Jen, A.Ch Yeh

Microstructure and property of a selective laser melting process induced oxide dispersion strengthened 17-4 PH stainless steel

J. Alloys. Compd., 803 (2019), pp. 30-41

ArticleDownload PDFView Record in ScopusGoogle Scholar

[32]

Li Wang, Chaofang Dong, Cheng Man, Decheng Kong, Kui Xiao, Xiaogang Li

Enhancing the corrosion resistance of selective laser melted 15-5 PH martensite stainless steel via heat treatment

Corrosion Science, 166 (2020), Article 108427

ArticleDownload PDFView Record in ScopusGoogle Scholar

[33]

H. Kimura

Precipitation Behavior and 2-step Aging of 17-4PH Stainless Steel

Tetsu-to-Hagane, 86 (2000), pp. 343-348

CrossRefView Record in ScopusGoogle Scholar

[34]

G. Yeli, M.A. Auger, K. Wilford, G.D.W. Smith, P.A.J. Bagot, M.P. Moody

Sequential nucleation of phases in a 17-4PH steel: Microstructural characterisation and mechanical properties

Acta. Mater., 125 (2017), pp. 38-49

ArticleDownload PDFView Record in ScopusGoogle Scholar

[35]

J.B. Ferguson, Benjamin F. Schultz, Dev Venugopalan1, Hugo F. Lopez, Pradeep K. Rohatgi, Kyu Cho, Chang-Soo Kim

On the Superposition of Strengthening Mechanisms in Dispersion Strengthened Alloys and Metal-Matrix Nanocomposites: Considerations of Stress and Energy

Met. Mater. Int., 20 (2014), pp. 375-388

CrossRefView Record in ScopusGoogle Scholar

[36]

H. Mirzadeh, A. Najafizadeh

Aging kinetics of 17-4 PH stainless steel

Mater. Chem. Phys., 116 (2009), pp. 119-124

ArticleDownload PDFView Record in ScopusGoogle Scholar

[37]

L.E. Murr, E. Martinez, J. Hernandez, Sh Collins, K.N. Amato, S.M. Gaytan, P.W. Shindo

Microstructures and Properties of 17-4 PH Stainless Steel Fabricated by Selective Laser Melting

J. Mater. Res. Technol, 1 (2012), pp. 167-177

ArticleDownload PDFView Record in ScopusGoogle Scholar

[38]

Y.F. Shen, L.N. Qiu, X. Sun, L. Zuo, P.K. Liaw, D. Raabe

Effects of retained austenite volume fraction, morphology, and carbon content on strength and ductility of nanostructured TRIP-assisted steels

Mater. Sci. Eng. A, 636 (2015), pp. 551-564

ArticleDownload PDFView Record in ScopusGoogle Scholar