Maraging steel

About: Maraging steel is a research topic. Over the lifetime, 1728 publications have been published within this topic receiving 19886 citations. The topic is also known as: martensitic ageing steel.

Effect of laser scanning strategies on texture, physical and mechanical properties of laser sintered maraging steel

Abstract: Direct Metal Laser Sintering (DMLS) is one of the most emerging metal Additive Manufacturing (AM) process due to its ability to quickly form complex designs with maximal surface finish. In this research, DMLS is used to additively manufacture 18% Ni maraging steel 300 samples by adopting a bidirectional and a cross-directional laser scanning strategy. The density, surface finish, texture, residual stress and mechanical properties of the DMLSed samples are investigated. Higher densification and surface finish are obtained using the cross-directional scan strategy. The formation of γ-austenite in the bi-directional scanning strategy is found to be nearly 60% in comparison to the cross-directional scan strategy. A preferential growth of columnar cells followed by epitaxial formation was found in both the directions for cross-directional scan strategy due to the rotation of heat flux and transformation of strong crystallographic texture into weaker ones. This resulted in a reduction of anisotropy and higher compressive residual stresses and mechanical properties. The outcomes of this research are likely to help in a better understanding of the DMLS AM process for fabrication of high surface finish, density and mechanical properties maraging steel parts by controlling their crystallographic texture.

Plastic anisotropy of additively manufactured maraging steel: Influence of the build orientation and heat treatments

Abstract: This experimental study investigates the combined effect of the three primary Additive Manufacturing (AM) build orientations (0°, 45°, and 90°) and an extensive array of heat treatment plans on the plastic anisotropy of maraging steel 300 (MS1) fabricated on the EOSINT M280 Direct Metal Laser Sintering (DMLS) system. The alloy's microstructure, hardness, tensile properties and plastic strain behaviour have been examined for various strengthening heat-treatment plans to assess the influence of the time and temperature combinations on plastic anisotropy and mechanical properties (e.g. strength, ductility). A comprehensive visual representation of the material's overall mechanical properties, for all three AM build orientations, against the various heat treatment plans is offered through time – temperature contour maps. Considerable plastic anisotropy has been confirmed in the as-built condition, which can be reduced by aging heat-treatment, as verified in this study. However, it has identified that a degree of transverse strain anisotropy is likely to remain due to the AM alloy's fabrication history, a finding that has not been previously reported in the literature. Moreover, the heat treatment plan (6h at 490 °C) recommended by the DMLS system manufacturer has been found not to be the optimal in terms of achieving high strength, hardness, ductility and low anisotropy for the MS1 material. With the use of the comprehensive experimental data collected and analysed in this study, and presented in the constructed contour maps, the alloy's heat treatment parameters (time, temperature) can be tailored to meet the desired strength/ductility/anisotropy design requirements, either for research or part production purposes.

Factors influencing the strength differential of high strength steels

Abstract: Room temperature tensile and compressive true stress-true strain curves of various high strength steels (quenched and tempered 4340 steel, 410 martensitic stainless steel, and H-11 steel; and aged 300-grade 18 Ni maraging steel) were analyzed to determine the effect of the various microstructures, on what has been termed the strength differential (SD),i.e., the strength level difference between the tensile and compressive flow curves. Care was taken to insure that the compressive deformation was homogeneous. Regardless of the amount of plastic deformation, the quenched and tempered steels exhibited a higher flow stress in homogeneous compressive deformation than for tensile deformation. The extent of the SD was dependent on tempering temperature. This observation is consistent with what others have observed regarding yield strength behavior of quenched and quenched-and-tempered steels. Despite the low carbon content, aged maraging steel also showed a greater resistance to homogeneous compressive deformation. Metallographic examination of the maraging steel revealed the banding that is indicative of segregation. However, homogenization had little effect on the SD despite a change in austenite grain size, reverted austenite content, and the austenite-to-martensite transformational strains shown by Goldberg to be present in segregated material.