Three-Dimensional Approach to Observing Growth of Blocks and Packets in Fe-18Ni Maraging Steel

2014 ◽  
Vol 783-786 ◽  
pp. 916-919 ◽  
Author(s):  
Shigekazu Morito ◽  
Show Yoshida ◽  
Rei Hayamizu ◽  
Taisuke Hayashi ◽  
Takuya Ohba ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundaries ◽  
Maraging Steel ◽  
Prior Austenite ◽  
Early Stage ◽  
Lath Martensite ◽  
Three Dimensional ◽  
Boundary Edge ◽  
Austenite Grain ◽  
Prior Austenite Grain

The present study aims to clarify the development of blocks and packets in lath martensite in Fe–18Ni maraging steel using three-dimensional observations. The specimens were step-quenched in order to clarify the sequential development of the three-dimensional morphology in a prior austenite grain. In a prior austenite grain, we found that five independent packets formed during the early stage of martensitic transformation. Four of the packets exist along the prior austenite grain boundaries and one packet grows from the boundary edge into the prior austenite grain. Each packet consists of a single block, although the fraction of martensitic transformation is 50.6%. The observed rules of the block-selection are as follows: (1) the blocks have near Kurdjumov–Sachs orientation relationship with adjacent austenite grains and elongated directions of the laths are parallel to adjacent grain boundaries and (2) transformation shear directions of the laths are parallel to adjacent grain boundaries.

A quantitative atom probe study of the Nb excess at prior austenite grain boundaries in a Nb microalloyed strip-cast steel

2012 ◽  
Vol 60 (13-14) ◽  
pp. 5049-5055 ◽  
Author(s):  
Peter J. Felfer ◽  
Chris R. Killmore ◽  
Jim G. Williams ◽  
Kristin R. Carpenter ◽  
Simon P. Ringer ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Prior Austenite ◽  
Cast Steel ◽  
Atom Probe ◽  
Austenite Grain ◽  
Strip Cast ◽  
Prior Austenite Grain

Nb segregation at prior austenite grain boundaries and defects in high strength low alloy steel during cooling

2017 ◽  
Vol 115 ◽  
pp. 165-169 ◽  
Author(s):  
Xianglong Li ◽  
Ping Wu ◽  
Ruijie Yang ◽  
Shoutian Zhao ◽  
Shiping Zhang ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Alloy Steel ◽  
Prior Austenite ◽  
High Strength ◽  
Low Alloy Steel ◽  
Austenite Grain ◽  
Prior Austenite Grain

Cavitation control in steels of high residual element content

1980 ◽  
Vol 295 (1413) ◽  
pp. 305-305 ◽  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Prior Austenite ◽  
Low Alloy Steels ◽  
Boundary Zone ◽  
Austenite Grain ◽  
Alloy Steels ◽  
Austenite Grain Boundary ◽  
Prior Austenite Grain ◽  
Transverse Boundary

The cavitational mode of failure of prior austenite grain boundaries in bainitic creep-resisting low alloy steels is now well established as a principal factor in the high incidence of cracking problems which has developed on modern power plant in recent years. The microstructural features dominating the cavitation process at the reheat temperature in a ½CMV bainitic steel of high classical residual level have been determined. The prior austenite grain boundaries become zones of comparative weakness ca . 1 pm thick at 700 °C and are incapable of sustaining significant shear loads. Deformation is therefore initiated by a relaxation of load, through a process of prior austenite grain boundary zone shear, from inclined to transverse boundaries such that a concentration of normal stress develops across the latter. The overall deformation is thereafter determined by cavitation of the transverse boundary zones, the necessary inclined boundary displacements being accommodated by further grain boundary zone shear. Transverse boundary cavitation is shown to be an essentially time-independent process of localized ductile microvoid coalescence resulting from the plastic deformation of the boundary zone.

scholarly journals Microstructural Influences on Fracture at Prior Austenite Grain Boundaries in Dual-Phase Steels

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3687 ◽  
Author(s):  
Luv Sharma ◽  
Ron Peerlings ◽  
Marc Geers ◽  
Franz Roters
Keyword(s):  
Grain Boundaries ◽  
Prior Austenite ◽  
Volume Element ◽  
Small Scale ◽  
Dual Phase ◽  
Damage Initiation ◽  
Austenite Grain ◽  
Dp Steels ◽  
Prior Austenite Grain

Dual phase (DP) steels provide good strength and ductility properties. Nevertheless, their forming capability is limited due to the damage characteristics of their constituting microstructural phases and interfaces. In this work, a specific type of interface is analysed, i.e., prior austenite grain boundaries (PAGBs). In the literature, prior austenite grain boundary fracture has been reported as an important damage mechanism of DP-steels. The influence of the morphology of phase boundaries near the PAGB and the role of the martensite substructure in the vicinity of a PAGB on damage initiation is analysed. The experimentally observed preferred sites of crack nucleation along the PAGB are assessed and clarified. A finite strain rate dependent crystal plasticity model accounting for the anisotropic elasto-plasticity of martensite (and also ferrite) was applied to an idealized volume element approximating a typical small-scale PAGB microstructure. The boundary value problem is solved using a fast Fourier transform (FFT) based spectral solver. The role of crystallography and geometrical features within the volume element is studied using simulations. Results are discussed considering possibly dominant regimes of elasticity and plasticity.

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