Direct laser freeform fabrication of high performance metal components

Abstract

This paper focuses on recent advances in direct freeform fabrication of high performance components via selective laser sintering (SLS). The application, known as SLS/HIP, is a low cost manufacturing technique that combines the strengths of selective laser sintering and hot isostatic pressing (HIP) to rapidly produce low volume or “one of a kind” high performance metal components. Direct selective laser sintering is a rapid manufacturing technique that can produce high density metal parts of complex geometry with an integral, gas impermeable skin. These parts can then be directly post‐processed by containerless HIP. The advantages of in situ encapsulation include elimination of a secondary container material and associated container‐powder interaction, reduced pre‐processing time, a short HIP cycle and reduction in post‐processing steps compared to HIP of canned parts. SLS/HIP is currently being developed under a DARPA/ONR program for INCONEL® 625 superalloy and Ti‐6Al‐4V, the demonstration components being the F‐14 turbine engine vane and the AIM‐9 missile guidance section housing base respectively.

An Overview of Densification, Microstructure and Mechanical Property of Additively Manufactured Ti-6Al-4V — Comparison among Selective Laser Melting, Electron Beam Melting, Laser Metal Deposition and Selective Laser Sintering, and with Conventional Powder

“…SLS is largely similar to the conventional PM and this explains that the microstructure of SLS Ti-6Al-4V is close to that of equilibrium state as with the PM or cast Ti-6Al-4V [79][80][81][82][83][84][85][86][87][88]. Figure 8 compares the microstructure of SLS Ti-6Al-4V with that of an HIP Ti-6Al-4V [81].…”

“…EOSINT M250X and EOISNT M270 are being used as the SLS machines for preparing AM Ti-6Al-4V [79][80][81][82][83][84][85][86][87][88]. The general working conditions and key machine/processing parameters are shown by Figure 5 and listed in Table 6.…”

Selective laser sintering: A qualitative and objective approach

“…5,49,61 This process mainly uses the CO 2 laser 7,9,36 as the heat source but an Nd:YAG laser has also been employed either independently 9,10,16,42,45,62 or in combination with a CO 2 laser as in the dual-beam technique. 4,41 In addition, diode lasers have been used to sinter a metal mixture and sand.…”

“…The materials include wax, cermet, ceramics, nylon/glass composite, metal-polymer powders, metals, alloys or steels, 7,9 polymers, 33,34 nylon, and carbonate. 35,36 Polycarbonate powders [36][37][38] and Bishphenol-A polycarbonate 39 12 and alloys (e.g., cobalt-based, nickelbased, 42,44 bronze-nickel, 19 pre-alloyed bronze-nickel, 28 Inconel 625, Ti6Al-4V, 45 stainless steel, 4 gas-atomized stainless steel 316L, 9,16,17 AISI 1018 carbon steel, 46 high-speed steel, 7,47 precoated foundry sand, 22 and alumina with polymer binder) 48 were tested for laser sintering. The results demonstrated that any material can be combined with a low-melting-point material that will serve as glue.…”

3D Residual Stresses in Selective Laser Melted Hastelloy X

“…The lasers equipment originally used could only melt materials with low melting points, for instance brass, and was not powerful enough to completely melt steel. Therefore, this manufacturing method could not meet the requirements for parts subjected to high stress levels or elevated temperatures, e.g., superalloys [4]. With time, the process control was improved and more powerful lasers were developed.…”