Thermal strain, permeability, and magnetization measurements of the ferromagnetic shape memory alloys Ni50+xMn27-xGa23 (x = 2.0, 2.5, 2.7) were performed. For x = 2.7, in which the martensite transition and the ferromagnetic transition occur at the same temperature, the martensite transition starting temperature TMs shift in magnetic fields around a zero magnetic field was estimated to be dTMs/...

Article history: Received: 23.12.2013. Received in revised form: 15.01.2014. Accepted: 15.01.2014. Subcritical austenite reverse transformation quenching was used to improve the mechanical properties of 30CrMnSi steel, and the microstructure and mechanical properties of the samples were analyzed by subcritical austenite reverse transformation quenching. Experimental results show that subcritica...

A finite element model coupled with a thermokinetic model is developed to predict the phase transformation of the laser deposition of AISI 4140 on a substrate with the same material. Four different deposition patterns, long-bead, short-bead, spiral-in, and spiral-out, are used to cover a similar area. Using a finite element model, the temperature history of the laser powder deposition (LPD) pro...

Mechanical properties of machined components are controlled by inducing phase transformations in the outer layer of the materials. Induction hardening is one such manufacturing process where the surface hardness is enhanced while the core is retained with the original structure and characteristics. In this study, a mathematical model had been developed to predict the hardness and the volume fra...

A generalized phase transformation kinetics model is used to understand the martensite to austenite transformation in a cold-rolled and annealed metastable AISI 301LN ultrafine-grained austenitic stainless steel. The model shows that the presence of interstitial nitrogen and heavy cold-rolling is important to promote fast transformation kinetics, through rapid nitrogen-diffusion and austenite n...

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...

This study was set to fundamentally investigate the characteristics of austenite reversion occurring in maraging steels additive-manufactured by laser powder bed fusion (L-PBF). The steel samples manufactured under different L-PBF process conditions (laser power P and scan speed v) were subjected heat treatments at 550°C for various durations, compared with results austenitized water-quenched s...

in this research, graphitization transformation of a commercial hypereutectoid steel called ck100 was studied by the dilatometric experiments at the range of 600 – 700 °c from prior martensitic structure. also the effect of quenching media on the initial graphitization time and completion of transformation has been discussed. also, graphitization transition from the different prior microstructu...

The influence of the free surface on martensitic transformation was examined by comparing the highest temperature at which martensite forms (MS), as measured using dilatometry, with surface–observations using confocal laser scanning microscopy. It is found that the proximity of the surface during confocal microscopy permits martensitic transformation to occur at a higher temperature, with a red...

The Ginzburg-Landau theory for multivariant martensitic phase transformations is advanced in three directions: the potential is developed that introduces the surface tension at interfaces; a mixed term in gradient energy is introduced to control the martensite-martensite interface energy independent of that for austenite-martensite; and a noncontradictory expression for variable surface energy ...