In this research, variant selection of martensite transformed from ultrafine-grained (UFG) austenite fabricated by accumulative roll bonding (ARB) process and subsequent annealing was investigated with respect tomorphology of parentaustenitic phase. The results show that the original shape of austenite grain is very effective factor in determiningthe preferred variants of martensite transformed...

Shape memory alloys exhibit a high damping capacity in the mktensite state. Results obtained from both DMA and cyclic tests under tension-compression load show that the martensite damping capacity in NiTi SMAs is a function of both strain amplitude and annealing temperature. Internal friction due to movements of martensite twin boundaries within both elastic (accommodation) and inelastic (reori...

The name martensite is after the German scientist Martens. It was used originally to describe the hard microconstituent found in quenched steels. Martensite remains of the greatest technological importance in steels where it can confer an outstanding combination of strength (> 3500MPa) and toughness (> 200MPam 1 2 ). Many materials other than steel are now known to exhibit the same type of soli...

This study investigated the microstructures of pearlite and martensite transformed from ultrafine-grained austenite in 0.45C steel and Vadded 0.45C steel. The mean prior austenite grain sizes were refined to be 4.5 μm in the 0.45C specimen and 2.4 μm in the V-added 0.45C specimen through cyclic heat treatment of austenitizing and water quenching, i.e., repetition of martensite § austenite trans...

The shape memory effect exhibited by Fe-Mn-Si based alloys is due to the y(f.c.c.)-e(h.c.p.) martensitic transformation. The martensitic transformation induced by traction at room temperature in a Fe16Mn-9Cr-5Si-4Ni (%mass) is here studied by optical microscopy, scanning electron microscopy, transmission electron microscopy and scanning tunnelling microscopy. The martensitic microstructure and ...

It is increasingly important in the context of high–manganese steels of the kind that lead to twinning–induced plasticity to be able to estimate the temperature at which ε–martensite forms when austenite is cooled. We find that the thermodynamic method used in similar calculations for α martensite cannot in many cases be implemented because of apparently imprecise thermodynamic data, a conclusi...

The formation of stress-induced α′′ martensite in a metastable β Ti-Mo-based alloy has been studied using X-ray diffraction and transmission electron microscopy. The martensite nucleates heterogeneously at pre-existing sub-grain boundaries by dissociation of the boundary dislocations which bow out on inclined planes. The growth of martensite laths from the resultant stacking faults occurs by th...

This conference paper briefly discusses different techniques for measuring the evolution of the martensite content in cold-rolled stainless steel 301LN sheets under mechanical loading. Three methods are employed to measure the martensite content: (1) micrography, (2) bulk magnetic induction, and (3) local magnetic permeability measurements. The first two methods require the extraction of sample...

Modulated phases occur in numerous functional materials like giant ferroelectrics and magnetic shape-memory alloys. To understand the origin of these phases, we employ and generalize the concept of adaptive martensite. As a starting point, we investigate the coexistence of austenite, adaptive 14M phase, and tetragonal martensite in Ni-Mn-Ga magnetic shape-memory alloy epitaxial films. We show t...

The redistribution of carbon after tempering of a novel nanocrystalline bainitic steel consisting of a mixture of supersaturated ferrite and retained austenite has been analyzed by atom probe tomography. No direct evidence supporting the additional carbon enrichment of austenite beyond that initially achieved during the bainite heat treatment was obtained during subsequent tempering of this hig...