Nitrogen Supersaturation into AISI420 Mold for Precise Machining

Abstract:

The plasma nitriding conditions and processing parameters were controlled to attain the high-density nitrogen ion and NH-radical populations and to form the nitrogen supersaturated layer into AISI420 type martensitic stainless steel mold substrate at 673 K for 14.4 ks and 28.8 ks. Thicker nitrided layer than 80 mm was attained for fine machining of the optical diffraction elements onto this nitrided AISI420 mold surface. The average hardness in this nitrogen supersaturated layer reached 1400 HV. After this hardness testing and microstructure analysis, the machinability test was performed to describe the ductile mode cutting behavior of nitrogen-supersaturated work by using the PCD (Poly-Crystalline Diamond)-chip tool. Higher average nitrogen solute content than 4 mass% was responsible for fine turning by PCD-chip and CVD (Chemical Vapor Deposition)-diamond coated cutting tools without any damages and for precisely finishing the mold surface with the lower maximum surface roughness than 10 nm on the machined mold surface. The low roughness and homogeneous machined surface profile proved that the nitrogen supersaturated AISI420 series stainless steel was adaptive as a stamping mold of chalcogenide glasses with high dimensional accuracy and demolding capacity.

• Periodical: Key Engineering Materials (Volume 926)
• Pages: 1591-1600
• DOI: https://doi.org/10.4028/p-w28az0
• Online since: July 2022
• Authors: Tatsuhiko Aizawa, Hiroshi Morita*, Tatsuya Fukuda
• Keywords: AISI420 Mold, Chalcogenide Lens, High Nitrogen Solute Content, Hydrophobicity, Machinability by PCD, Mold-Stamping, Plasma Nitriding, Thick Nitrogen Supersaturated Layer

References

[1] K. M. Budinski, J. C. PulverJayson, J. N. Eugene. G. Hill, D. A. Richards, Glass mold material for precision glass molding. US-Patent with US6363747B1 (2001).

[2] Q. Yu, T. Zhou, Y. He, P. Liu, X. Wang, Y. Jiang, J. Yan, Annealed high-phosphorous electroless Ni-P coatings for producing molds for precision glass molding. Mater. Chem. Phys. 262 (32) (2021) 124297.

DOI: 10.1016/j.matchemphys.2021.124297

[3] K. Saito, Introduction to ion nitriding in Hokunetsu. (2018). http://hokunetsu.com/ products/003/ (retrieved at 2021/11/16).

[4] H. Aghajani, S. Behrangi, Pulsed DC glow discharge plasma nitriding. In: Plasma Nitriding of Steels, Springer (2016) 71-125.

DOI: 10.1007/978-3-319-43068-3_3

[5] T. Bell, Surface engineering of austenitic stainless steel. Surf. Eng. 18 (2002) 415-422.

[6] H. Dong, S-phase surface engineering of Fe-Cr, Co-Cr and Ni-Cr alloys. International Materials Reviews. 55(2) (2011) 65-98.

DOI: 10.1179/095066009x12572530170589

[7] T. Aizawa, Low temperature plasma nitriding of austenitic stainless steels. Ch. 3 In: Stainless Steels. IntechOpen, London, UK (2018) 31-50.

DOI: 10.5772/intechopen.78365

[8] Lu S.; Zhao X., Wang S., Li J., Wei W., Hu J., Performance enhancement by plasma nitriding at low gas pressure for 304 austenitic stainless steel. Vacuum. 2017; 145: pp.334-339.

DOI: 10.1016/j.vacuum.2017.09.020

[9] T. Aizawa, T. Shiratori, T. Komatsu, Micro-/nano-structuring in stainless steels by metal forming and materials processing. Ch. 5 In: Electron Crystallography. IntechOpen, London, UK (2020) 101-122.

DOI: 10.5772/intechopen.91281

[10] F. Borgioli, E. Galvanetto, T. Bacco, Low temperature nitriding of AISI300 and 200 series austenitic stainless steels. Vacuum 12 (2016) 51–60.

DOI: 10.1016/j.vacuum.2016.02.009

[11] A. Farghali, T. Aizawa, T. Yoshino, Microstructure/mechanical characterization of plasma nitrided fine-grain austenitic stainless steels in low temperature. J. Nitrogen 2 (2021) 244-258.

DOI: 10.3390/nitrogen2020016

[12] T. Katoh, T. Aizawa, T. Yamaguchi: Plasma assisted nitriding for micro-texturing onto martensitic stainless steels. Manufacturing Review 2 (2) (2015) 1-7.

DOI: 10.1051/mfreview/2015004

[13] D. J. Djoko, T. Aizawa, Formation of expanded martensite in plasma nitrided AISI420 stainless steel. Pro. 8th SEATUC Conf. (Johor-Balu, Malaysia; March 2014) (CD-ROM).

[14] A. Farghali, T. Aizawa, Nitrogen supersaturation process in the AISI420 martensitic stainless steels by low temperature plasma nitriding. ISIJ International. 58 (3) (2018) 401-407.

DOI: 10.2355/isijinternational.isijint-2017-451

[15] T. Aizawa, T. Fukuda, Microstructure and micro-machinability of plasma nitrided AISI420 martensitic stainless steels at 673 K. Top-5 Cont. to Mater. Sci. 6th Ed. Avid Science (2019) 2-23.

[16] T. Aizawa, H. Morita, T. Fukuda, High machinability of plasma-nitrided HPM80 dies at 673K by PCD-tools for hot mold-stamping. Procedia Manufacturing 47 (2020) 725-731.

DOI: 10.1016/j.promfg.2020.04.223

[17] T. Aizawa, I, Rsadi, E. E. Yunata, High density RF-DC plasma nitriding under optimized conditions by plasma-diagnosis. J. Appl. Sci. (2021) (in press).

DOI: 10.3390/app12083706

[18] C. Domain, C. S. Becquart, J. Foct, Ab initio study of foreign interstitial atom (C, N) interactions with intrinsic point defects in a-Fe. Phys. Rev. B 69 (2004) 144122.

DOI: 10.1103/physrevb.69.144112

[19] T. Aizawa, T. Shiratori, T. Yoshino, Y. Suzuki, T. Komatsu, Nitrogen supersaturation of AISI316/316L/316LN stainless steels at 673 K for hardening and microstructure control. Ch. In: Stainless Steels, InTechOpen, London, UK (2021) (in press).

DOI: 10.5772/intechopen.102387

[20] Y. Hiraoka, K. Inoue, Prediction of nitrogen distribution in steels after plasma nitriding. Denki-Seiko 86 (2010) 15-24.

[21] T. Aizawa, S-I. Yoshihara, Inner nitriding behavior and mechanism in stainless steels at 753 K and 623 K. SEATUC J. Sc. Eng. (SJSE) 1 (2019) 13-20.

[22] T. Aizawa, T. Yoshino, K. Morikawa, S-I. Yoshihara, Microstructure of plasma nitrided AISI420 martensitic stainless steel at 673 K. J. crystals 9 (2), 60 (2019) 1 - 10.

DOI: 10.3390/cryst9020060

[23] Y. Imai, T. Murata, M. Sakamoto, High nitrogen steels. (2005) Agune.

[24] B. R. Lawn, O. Borrero-Lopez, H. Huang, Y. Zhang, Micromechanics of machining and wear in hard and brittle materials. J. Amcer. Soc. 104 (1) (2021) 5-22.

DOI: 10.1111/jace.17502

[25] P. Parhad, A. Likhite, J. Bhatt, D. Peshwe, The effect of cutting speed and depth of cut on surface roughness during machining of austempered ductile iron. Trans. Indian Institute Metals. 68 (2015) 99-108.

DOI: 10.1007/s12666-014-0439-y