Laser additive manufacturing of steels

Abstract

Despite strong interest from many industrial sectors driving demand and advancements in laser additive manufacturing (LAM) of steels, some issues remain as barriers limiting the current industrial applications, such as defects, residual stress, scattered, inadequate or/and anisotropic properties. To overcome these problems, several effective approaches have been developed to control and/or enhance the properties of LAM produced steel components. To help researchers and engineers attain up-to-date information and knowledge in this rapidly growing area, the present work provides an overview of current research in LAM of steels, in particular austenitic steels, ferritic steels, duplex steels and martensitic steels, with a focus on understanding the interrelation between process, microstructure and mechanical properties. This review also includes substantive discussions on the effects of processing parameters, their interactions and post-LAM treatments on the metallurgy, microstructure and properties. In addition, the advances, ongoing challenges and outlooks in LAM of steels are highlighted.

Laser Additive Manufacturing of Duplex Stainless Steel via Powder Mixture

“…To determine the optimal process parameters a parameter study was carried out for the X2CrNiMo17-12-2 alloy, for the X2CrNiMoN25-7-4 alloy and the mixed alloy 50% X2CrNiMo17-12-2 + 50% X2CrNiMoN25-7-4, respectively. The volume energy introduced via the laser can be considered as a central parameter [8], which determines the melting and microstructure formation behavior in the PBF-LB/M process; this volume energy density E V under the various process conditions is calculated according to the following equation [20,21]:…”

“…The irregular pores, known as lack of fusion pores, are caused by insufficient melting and fusion of the powder particles. Higher laser energy density leads to a more complete melting of the particles and an increasing overlap between two adjacent layers, reducing or eliminating the lack of fusion pores [8,27]; however, with too high a laser energy input, the melting mode will transit to the keyhole mode [28]. Large keyhole pores in near-spherical shape are generated at the melt pool bottom when the vapor cavity formed due to metal evaporation collapses.…”

“…Laser additive manufacturing of metals has been of great interest in recent years. A wide range of metallic materials, such as nickel alloys, titanium alloys, aluminum alloys, copper alloys as well as iron-based alloys, have been processed via laser additive manufacturing [4][5][6][7][8]. Steel grades available for laser additive manufacturing are mainly austenitic stainless steels, maraging steels, precipitation hardenable stainless steels, as well as tool steels.…”

“…Steel grades available for laser additive manufacturing are mainly austenitic stainless steels, maraging steels, precipitation hardenable stainless steels, as well as tool steels. The steels described above satisfy typical requirements of the material properties required for successive PBF-LB/M production; this means that they provide, inter alia, a sufficient weldability to prevent crack formation during fast solidification and cooling during PBF-LB/M [8].…”

Mechanical Properties and Fracture Behavior of Laser Powder-Bed-Fused GH3536 Superalloy

“…Laser powder-bed fusion (L-PBF) is one of the laser-based additive manufacturing methods with the capability of higher shape precision, lower material waste, and fewer processing steps than conventional manufacturing technologies [8,9]. The mechanical properties of as-printed samples are often reported as higher-strength but lower-ductility compared to the casting or wrought parts [10,11].…”