Evaluation of Maraging Steel Produced Using Hybrid Additive/Subtractive Manufacturing

Sheida Sarafan,Fabrice Bernier,Marjan Molavi-Zarandi,Javad Gholipour,Josh Soost,Mathieu Brochu,Fatih Sikan,Priti Wanjara,Mahmoud Osman

doi:10.3390/jmmp5040107

Abstract

Hybrid manufacturing is often used to describe a combination of additive and subtractive processes in the same build envelope. In this research study, hybrid manufacturing of 18Ni-300 maraging steel was investigated using a Matsuura LUMEX Avance-25 system that integrates metal additive manufacturing using laser powder bed fusion (LPBF) processing with high-speed machining. A series of benchmarking coupons were additively printed at four different power levels (160 W, 240 W, 320 W, 380 W) and with the integration of sequential machining passes after every 10 deposited layers, as well as final finishing of selected surfaces. Using non-contact three-dimensional laser scanning, inspection of the final geometry of the 18Ni-300 maraging steel coupons against the computer-aided design (CAD) model indicated the good capability of the Matsuura LUMEX Avance-25 system for net-shape manufacturing. Linear and areal roughness measurements of the surfaces showed average Ra/Sa values of 8.02–14.64 µm for the as-printed walls versus 0.32–0.80 µm for the machined walls/faces. Using Archimedes and helium (He) gas pycnometry methods, the part density was measured to be lowest for coupons produced at 160 W (relative density of 93.3–98.5%) relative to those at high power levels of 240 W to 380 W (relative density of 99.0–99.8%). This finding agreed well with the results of the porosity size distribution determined through X-ray micro-computed tomography (µCT). Evaluation of the static tensile properties indicated that the coupons manufactured at the lowest power of 160 W were ~30% lower in strength, 24% lower in stiffness, and more than 80% lower in ductility relative to higher power conditions (240 W to 380 W) due to the lower density at 160 W.

Highlights

Since being introduced in the early 1960s, the 18% nickel (18Ni) family of maraging steels remains important to the aerospace, defense, nuclear, as well as the tool and die industries due to their unique combination of different properties, including high strength, high hardness, excellent toughness, ease of welding, good machinability, and dimensional stability [1,2]
To understand the surface quality of the 18Ni-300 maraging steel produced by hybrid (LPBF) manufacturing, the average values of the different roughness parameters were measured on linear profiles and surface areas of the as-printed and machined faces of the
Sa and Sq were reported to be suitable areal parameters for describing the surfaces produced in laser powder bed fusion (LPBF) additive manufacturing (AM) applica

Summary

Introduction

Since being introduced in the early 1960s, the 18% nickel (18Ni) family of maraging steels remains important to the aerospace, defense, nuclear, as well as the tool and die industries due to their unique combination of different properties, including high strength, high hardness, excellent toughness, ease of welding, good machinability, and dimensional stability [1,2]. To date, this improved cooling efficiency—which was made possible in maraging steel parts designed with novel conformal channels and fabricated using metal AM technologies ( with LPBF processing)—has reduced process cycle times in injection molding [12] of plastics and, more recently, in high-pressure die casting of metals [13], where the pressures and temperatures are significantly greater.

Results

Discussion

Conclusion