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.

Characterization of Reverted Austenite during Prolonged Ageing of Maraging Steel CORRAX

Abstract: Microstructure and mechanical properties were studied in CORRAX maraging steel during prolonged ageing up to 300 h at 798 K. Strengthening of maraging steel was caused by the formation of an intermetallic phase enriched in Ni and Al which exhibits an ordered B2 (CsCl) superlattice structure. Precipitation hardening was accompanied by an increase in micro-hardness with peak hardness after about 12 h of ageing. After 300 h of ageing, the micro-hardness value is still high, corresponding to 94% of the peak hardness. The reverse transformation of martensite to austenite does not take place during prolonged ageing as shown by X-ray and electron backscatter diffraction analyses. The experimentally determined amount of austenite (1-2 vol.%) is in good agreement with the calculated value (about 2.5 vol.%).

Effect of the as-built microstructure on the martensite to austenite transformation in a 18Ni maraging steel after laser-based powder bed fusion

Abstract: During laser-based powder bed fusion, the non-equilibrium solidification conditions promote local elemental segregation, leading to a characteristic microstructure composed of cellular walls. These walls can display either low carbon BCC martensite or FCC retained austenite crystal structures, thus affecting the subsequent isochronal or isothermal martensite to austenite phase transformation mechanisms. In the present study, the effect of the non-homogeneous as-built microstructure on the martensite-to-austenite reversion phenomena was studied for a 18Ni maraging steel fabricated by laser-based powder bed fusion. In-situ synchrotron X-ray diffraction was used to retrieve the austenite volume fraction and lattice parameter evolution during the physical simulation of continuous heating cycles to the austenitic field; and during isothermal tempering cycles throughout the inter-critical tempered martensite + austenite (α’ + γ) field. The as-built microstructure resulted in the expansion of the inter-critical α’ + γ field during very slow heating rates. This was associated to the synergic effects of compositional segregations (anticipating reversion) and pre-existing retained austenite (delaying solubilization). During conventional inter-critical tempering, the as-built microstructure did not fundamentally alter the austenite reversion kinetics, resulting in similar high temperature microstructures at the end of the isothermal stage relative to the solution treated state.

Influence of strength differential effect on material effort of a turbine guide vane based on thermoelastoplastic analysis

Abstract: The strength differential (SD) effect has been observed in many iron-based metals such as 4310, 4330, maraging steel, and HY80 steels as well as titanium, aluminium 2024-T351, magnesium, and nickel-based super alloys such as aged Inconel 718. Moreover, the SD effect increases with temperature. The Huber–Mises–Hencky (HMH) J2 yield condition is insufficient to simulate the response of metals that exhibit the SD effect. Our work demonstrates the importance of taking into account the SD effect during strength analysis of turbine components. Two yield conditions are considered: the HMH condition and the SD-dependent Burzynski condition. The equivalent stresses produced by these conditions in the elastic state are compared. Plastic zone areas and effective strain values predicted by the two conditions are compared. Our investigation was performed based on thermal-fluid-structure interaction (FSI) analysis of a turbine guide vane made of a nickel-based super alloy that exhibits the SD effect. Conjugate he...

The Effect of Strain Rate on Yielding in High Strength Steels

Abstract: : The effect of strain rates ranging from 0.0001 to 10 in/in/sec. on the yield strengths of several high strength alloy steels is investigated. Quenched and tempered type alloys exhibit two regions of strain rate sensitivity with the strain rate dividing the sensitive and insensitive regions varying from 0.5 to greater than 10 in/in/sec, depending on composition, microstructure and grain size. At the higher rates a power law relationship is found which is consistent with a yielding model involving breakaway of dislocations from solute atmospheres. Maraging steel exhibits a continuous power law strain rate sensitivity over the entire range. (Author)

Alloys of iron and reversibility of martensitic transformations

Abstract: The origin of irreversibility, reversibility, course and completeness of martensitic transformations are discussed using the following alloys of iron as examples: 1. I~reversible transformation: Fe-C, Fe-Nix, maraging steel 2. Reversibility in homogeneous solid solutions: Fe-Ni, Fe-Ni-C, Fe-Mn 3. Reversibility due to order or coherent particles: Fe-Pt, Fe--Ni-X, Fe-Ni-Co-Ti 4. Effects of external stress and mechanical properties on Ms 5. Effects of external magnetic fields and magnetism/antiferromagnetism in austenite. The feasibility of shape memory steels is finally discussed.