Structural and Tribological Assessment of Biomedical 316 Stainless Steel Subjected to Pulsed-Plasma Surface Modification: Comparison of LPBF 3D Printing and Conventional Fabrication.

Yuliia Chabak,Karol Kovaľ,Tatiana Pastukhova,Ivan Petryshynets,Angeliki G Lekatou,Victor Fedun,Vadym Zurnadzhy,Iurii Bogomol,Bohdan Efremenko,Vasily Efremenko

doi:10.3390/ma14247671

Abstract

The structural features and nanoindentation/tribological properties of 316 stainless steel fabricated by conventional rolling and laser-based powder bed fusion (LPBF) were comparatively investigated regarding the effect of surface-pulsed plasma treatment (PPT). PPT was performed using an electrothermal axial plasma accelerator under a discharge voltage of 4.5 kV and a pulse duration of 1 ms. Optical microscopy, scanning electron microscopy, X-ray diffraction, nanoindentation measurements and tribological tests were applied to characterize the alloys. The LPBF steel presented almost the same modulus of elasticity and double the hardness of rolled steel. However, the LPBF steel manifested lower dry-sliding wear resistance compared with its wrought counterpart due to its porous structure and non-metallic inclusions. Conversely, LPBF steel showed three times higher wear resistance under sliding in simulated body fluid (SBF), as compared with wrought steel. PPT led to steel modification through surface melting to a depth of 22–26 μm, which resulted in a fine cellular structure. PPT moderately improved the dry-sliding wear resistance of LPBF steel by fusion of pores on its surface. On the other hand, PPT had almost no effect on the SBF-sliding wear response of the steel. The modification features were analyzed using a computer simulation of plasma-induced heating.

Highlights

The microstructure and properties of laser-based powder bed fusion (LPBF)-fabricated 316L steel have been the focus of many researchers
316L steel specimens were fabricated by LPBF using a 3D printer (ProX DMP 320 by 3D Systems, Rock Hill, SC, USA) equipped with a fiber laser and a working camera
The microstructure and sliding wear performance of 316 stainless steel manufactured by conventional rolling and laser-based powder bed fusion (LPBF) were investigated in the as-received state and after pulsed-plasma treatment (PPT)

Summary

Introduction

Additive manufacturing (AM) has often been used for the fabrication of 316L components [6,7,8]. Laser-based powder bed fusion has been proven an effective AM technique for the fabrication of small parts of sophisticated shape, allowing a significant reduction in manufacturing costs and time [1]. The microstructure and properties of LPBF-fabricated 316L steel have been the focus of many researchers. Suryawanshi et al [9] attributed the microstructure refinement of LPBF 316L to the large thermal gradient in the liquid metal under the laser beam, in contrast to to hot-rolled 316L. The effect of LPBF process parameters on the properties of

Methods

Discussion

Conclusion