Modelling the Strengthening and Softening Mechanisms in Maraging Steel 250

Jacob, Kevin; Dixit, Saurabh; Jaya, Balila Nagamani

doi:10.1007/978-981-16-8724-2_33

Cited by 1 publication

(2 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Maraging steels are known to undergo planar slip, both in the as-processed state (due to short range ordering (SRO) [9]) and peak-aged conditions (due to coherent, shearable precipitates) [10]. Transmission electron microscopy (TEM) has been used to identify the signature of planar slip as a deformation mechanism in Fe-Ni alloys, characterised by dislocation arrays, slip bands, dislocation dipoles etc [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…In such systems, dislocations move in well-defined but parallel slip planes [14]. Planar slip leads to anomalous behaviour such as low ratio of ultimate tensile strength (UTS) to yield strength, break-down of Considère's criteria, increased slip velocity, and premature softening of the tensile curve [10,[18][19][20]. Fe-Ni based maraging steel consists of soft martensite, leading to a tensile failure strain of ∼20% [18], making it amenable to deformation processing.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Micro-mechanisms of failure in nano-structured maraging steels characterised through in situ mechanical tests

Jacob¹,

Sahasrabuddhe²,

Hohenwarter³

et al. 2022

Nanotechnology

Self Cite

View full text Add to dashboard Cite

High-pressure-torsion (HPT) processing introduces a large density of dislocations that form sub-grain boundaries within the refined nano-scale structure, leading to changes in precipitate morphology compared to hot-rolled maraging steels. The impact of such nanostructuring on the deformation and fracture micro-mechanisms is being reported for the first time using in-situ characterization techniques along with transmission electron microscopy and atom probe tomography analysis, in this study. Digital image correlation has been used to quantify the full field strain maps in regions of severe strain localization as well as to determine the fracture toughness through critical crack tip opening displacements. It is seen that the phenomenon of planar slip leads to strain softening under uniaxial deformation and to crack branching under a triaxial stress state in hot rolled maraging steels. On the other hand, nano-structuring after HPT processing creates a large number of high angle grain boundaries as dislocation barriers, leading to strain hardening under uniaxial tension and nearly straight crack path with catastrophic fracture under triaxial stress state. Upon overaging, the hot-rolled sample shows signature of transformation induced plasticity under uniaxial tension, which is absent in the HPT processed overaged samples, owing to the finer reverted austenite grains containing higher Ni concentration in the latter. In the overaged fracture test samples of both the hot-rolled and HPT conditions, crack tips show a signature of strain induced transformation of the reverted austenite to martensite, due to the accompanying severe strain gradients. This leads to a higher fracture toughness even while achieving high strengths in the overaged conditions of the nanocrystalline HPT overaged samples. The results presented here will aid in design of suitable heat treatment or microstructure engineering of interface dominated nano-scale maraging steels with improved damage tolerance.

show abstract