Feasability Investigation for Laser Powder Bed Fusion of High-Speed Steel AISI M50 with Base Preheating System

Jasmin Saewe,Johannes Henrich Schleifenbaum,Andreas Vogelpoth,Christoph Gayer

doi:10.1007/s00501-019-0828-y

Abstract

Laser Powder Bed Fusion (LPBF) is an additive manufacturing process employed in the aerospace, automotive, and medical industries. In these sectors, nickel-, aluminium-, and titanium-based alloys are mainly used for various applications. Yet, only few of the commonly used steels have been qualified for the LPBF process in the mechanical engineering industry, which normally uses hot work tool steels with less than 0.5 wt.-% carbon content. However, many applications need high wear-resistant steel alloys with high hardness, both of which can be achieved with a higher carbon content, like in high-speed steels. But when processed with LPBF, these steels often form cracks, making the process very challenging.In this feasibility investigation, we demonstrate that LPBF can be used to manufacture dense and crack-free specimens with a hardness of over 62 HRC (as built) from high-speed steel AISI M50 (carbon content of 0.8 wt.-%). Furthermore, we evaluate the influence of typical LPBF process parameters, especially of preheating temperatures up to 500 ℃, on the microstructure of the specimens.

Highlights

Laser Powder Bed Fusion (LPBF), known as Selective Laser Melting (SLM), is an Additive Manufacturing (AM) process used in multiple industries, such as aerospace, automotive, and medical engineering [1,2,3]
We demonstrate that LPBF can be used to manufacture dense and crack-free specimens with a hardness of over 62 HRC from high-speed steel AISI M50
We evaluate the influence of typical LPBF process parameters, especially of preheating temperatures up to 500 °C, on the microstructure of the specimens

Summary

Introduction

Laser Powder Bed Fusion (LPBF), known as Selective Laser Melting (SLM), is an Additive Manufacturing (AM) process used in multiple industries, such as aerospace, automotive, and medical engineering [1,2,3]. Most steels commonly used with LPBF are austenitic stainless steels AISI 316L (EN 1.4404) and AISI 304L (EN 1.4306), maraging steel 1.2709 or hardenable stainless steels 17-4 PH (EN 1.4545) and 15-5 PH (EN 1.4548) [2, 5, 6] These alloys have insufficient wear resistance and, cannot be used in the production of rolling bearings as they would not withstand the loads. Bearing steels are special tool steels and are commonly used for this application These steels have similar properties as high-speed steels and are suitable for the operating conditions to which a rolling bearing is subjected. These steels often have a high carbon content (>0.4 wt.-%) and are considered as unweldable

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