Effect of Combined Tempering and Aging in the Austenite Reversion, Precipitation, and Tensile Properties of an Additively Manufactured Maraging 300 Steel

Abstract

Maraging 300 is an ultrahigh strength steel with significant alloy addition, resulting in a martensitic matrix hardened by precipitation through aging treatment. In these steels, intercritical tempering can provide reverted austenite and precipitation of intermetallic products, increasing the ductility of additively manufactured parts due to austenite presence. Studies deal with postprocessing of additive manufactured parts of maraging steel; however, few focused on phases evolution during the heat treatments and their mechanical response. In the present work, a maraging 300 steel processed by laser-based powder-bed fusion was studied with a focus on microstructural and mechanical properties after applying several postprocessing heat treatments. Tensile tests assessed the mechanical properties, and the microstructure was analyzed by scanning and transmission electron microscopy. A synchrotron beamline with x-ray diffraction was used to conduct in situ measurements of martensite and austenite evolution. The in situ phase evolution revealed that isothermal heat treatments were efficient in promoting martensite-to-austenite reversion. Likewise, the presence of austenite significantly enhanced the ductility, however, at some mechanical strength expense.

Microstructural and mechanical characterization of additively manufactured parts of maraging 18Ni300M steel with water and gas atomized powders feedstock

“…In the diffractograms exhibited in Fig. 6, the presence of both α' and γ phases can be observed in the powders and the printed parts of GA and WA batches, in line with findings from other studies on this subject [8,9,53]. Secondary phases, such as intermetallic precipitates and oxides, were not detected, most likely due to their volumetric fraction falling below the detection limit of the conventional X-ray diffractometers [53,54].…”

“…2 (e) and (f), the GA batch has a normal particle size distribution between 20 and 40 μm (normal distribution). This range is commonly used for LPBF processing of 18Ni300M steel powders [7][8][9]18]. On the other hand, the WA batch has a bimodal particle size distribution, with two predominant ranges: between 20 and 40 μm and between 60 and 100 μm.…”

“…Currently, works involving 18Ni300M steel processed by LPBF are focused on optimizing its mechanical properties through the study of process or heat treatment parameters [1,[6][7][8][9]. However, the characteristics of the particulate material used during AM can be important in order to understand the properties of manufactured parts.…”

Influence of in-situ process parameters, post heat treatment effects on microstructure and defects of additively manufactured maraging steel by laser powder bed fusion—A comprehensive review

“…The only restriction is the chamber size. Marangoni convection may be used by mixing and stirring the molten metal, to produce anisotropic microstructure during rapid solidification through the use of conduction, convection and radiation [47][48][49]. This is due to the inputs of process parameters including base plate temperature, laser scanning strategy, build direction etc The laser powder bed fusion (LPBF) technique plays a vital role in the field of additive manufacturing for a number of important reasons, like complex geometries, material diversity, Rapid prototyping and shorter lead times, Customization and personalization, Lightweighting and material efficiency.…”

Short-Time Heat Treatment for Ti–6Al–4V Alloy Produced by Selective Laser Melting

“…13) From this background, many fundamental studies have been carried out in recent years to estimate the basic properties of SLM-produced titanium alloy, 46) nickelbased alloy, 710) aluminum alloy, 1114) stainless steel 1518) and maraging steel. 19,20) The material examined in this study was SLM-produced Ti6Al4V alloy (SLM material). As Ti6Al4V alloy is a standard ¡ + ¢ titanium alloy with high specific strength and excellent corrosion resistance, it has been used in a wide range of engineering applications such as the aerospace industries and the medical implant industries.…”