We have investigated the possibility of producing a magnetic encoder by an innovative process. Instead of turning grooves in the encoder bar for precise positioning, we incorporated the information in 304L stainless steel by transforming the austenite to martensite after bar extrusion in liquid nitrogen and marking it with a laser, which caused a local transformation of martensite back into aus...

The most efficient way to tune microstructures and mechanical properties of metallic alloys lies in designing and using athermal phase transformations. Examples are shape memory alloys and high strength steels, which together stand for 1,500 million tons annual production. In these materials, martensite formation and mechanical twinning are tuned via composition adjustment for realizing complex...

Combinatorial nanocalorimetry and synchrotron x-ray diffraction were combined to study the martensite-austenite (M-A) phase transformation behavior of Ni-Ti-Hf shape memory alloys. A thin-film library of Ni-Ti-Hf samples with a range of compositions was deposited on a parallel nano-scanning calorimeter device using sputter deposition. Crystallization of each amorphous as-deposited sample by loc...

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...

We have investigated the relation between the softening of elastic constants and martensitic transformation in Fe3Pt, which exhibits various kinds of martensitic transformation depending on its long-range order parameter S. The martensite phases of the examined alloys are BCT (S = 0.57), FCT1 (S = 0.75, c/a < 1) and FCT2 (S = 0.88, c/a > 1). The elastic constants C′ and C44 of these alloys decr...

Strong steels also have to be tough and hence rely on fine microstructures such as bainite or martensite, produced commercially by continuous cooling transformation. Depending on the detailed requirements, the steel-design process may explicitly require other higher temperature phases to be absent in the final microstructure. Such a procedure can be made easier by the availability of a good met...

Susceptibility of three lean-alloyed ferritic-austenitic stainless steels to hydrogen-induced delayed cracking was examined, concentrating on internal hydrogen contained in the materials after production operations. The aim was to study the role of strain-induced austenite to martensite transformation in the delayed cracking susceptibility. According to the conducted deep drawing tests and cons...

The mechanical and magnetic properties of Ni-Mn-Sb intermetallic compounds are closely related to the martensitic transformation and martensite variant organization. However, studies of these issues are very limited. Thus, a thorough crystallographic investigation of the martensitic transformation orientation relationship (OR), the transformation deformation and their impact on the variant orga...

Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels' performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano sc...

A phenomenological description of martensitic transformation is proposed on the basis of such parameters as: a degree of lattice coherency between austenite and martensite phases, mobility of interphase boundaries, elastic energy stored during martensitic transformation and degree of its relaxation. Son),: experimental results confirming the proposed ideas are presented.