Sinter hardening enables the production of P/M parts with high strength and apparent hardness after sintering, eliminating the need for a post sintering heat treatment. The availability of sintering furnaces with improved cooling capacity combined with the development of low alloy steel powders specifically designed for sinter hardening make this process particularly attractive for parts that a...

The martensite steels produced by quenching and tempering has been used for machine structural use. Martensite in ferrite-martensite dual-phase steels (hereinafter, DP steels) also has important roll in strengthening of the automobile steel sheets. Therefore the importance of analyzing the microstructure and their mechanical properties of the martensite has been increased year by year. Many res...

to investigate the effect of tempering treatment on mechanical properties and the microstructure ofdin 1.4021 martensitic stainless steel, austenite treatment was conducted for the samples at 1000ºc temperature for 60 min and then the samples were oil quenched. later, tempering treatments wereperformed for the samples at 500 ºc and 700 ºc temperatures for 2 and 5 h, respectively; then quenching...

as the turbine industries need to manufacture turbine blades made of martensitic stainless steel aisi 420 with high toughness and wear resistance, local laser hardening has become more and more important. in this research, surface of the samples was initially hardened by high-power pulsed laser beam; then, optimum parameters of hardening were calculated and wear resistance of surface hardened s...

Foams with 55% and 76% open porosity were produced from a Ni-Mn-Ga magnetic shape-memory alloy by replication casting. These polycrystalline martensitic foams display a fully reversible magnetic-field-induced strain of up to 0.115% without bias stress, which is about 50 times larger than nonporous, fine-grained Ni-Mn-Ga. This very large improvement is attributed to the bamboolike structure of g...

The effect of martensite transformations of different types on the misorientation of austenite crystalline lattice, which characterizes the degree of structure fragmentation, was investigated for Fe-Ni and Fe-Mn alloys. As a result of multiple face-centered cubic (f.c.c.)-body-centered cubic (b.c.c.)-f.c.c. transformations, an austenite single-crystalline specimen is transformed in a polycrysta...

Shape Memory Alloys (SMA) are now well recognized as potential materials for structural control. The optimised integration of some SMA devices in a mechanical structure for passive structural damping requires a predictable modelling. At first experimental and numerical studies have been performed on a CuAlBe beam under harmonic flexion, leading to a qualitative modelling based on the material t...

An overview will be given of some recent results of microstructural electron microscopy studies on martensitic systems. The precursor structure observed in a ternary Ni-Mn-Ti alloy and its correlation with the ensuing stacking sequence is presented. New types of materials of a well known alloy, in casu splat-cooled and nanoscale thin films of Ni-A1 are investigated revealing particular morpholo...

Thermal and structural austenite to martensite reversible transition was studied in melt spun ribbons of Ni50Mn40Sn5Co5, Ni50Mn37.5Sn7.5Co5 and Ni50Mn35Sn10Co5 (at. %) alloys. Analysis of X-ray diffraction patterns confirms that all alloys have martensitic structure at room temperature: four layered orthorhombic 4O for Ni50Mn40Sn5Co5, four layered orthorhombic 4O and seven-layered monoclinic 14...

A finite element approximation of the thin film limit for a sharp interface bulk energy for martensitic crystals is given. The energy density models the softening of the elastic modulus controlling the low-energy path from the cubic to the tetragonal lattice, the loss of stability of the tetragonal phase at high temperatures and the loss of stability of the cubic phase at low temperatures, and ...