Search results for "Marte"

Study of the Hydrogen Embrittlement Sensitivity of an X4CrNiMo 16.5.1 Stainless Steel and the Associated Electron Beam Weld

2015

X4CrNiMo 16.5.1 steel (commercial name APX4) is a low carbon martensitic stainless steel known for its remarkable mechanical characteristics and its good resistance to corrosion. The use of APX4 in the manufacture of high pressure gas vessels requires a thorough understanding of its resistance to Hydrogen Embrittlement (HE) as the gas can contain traces of hydrogen, and martensitic steels, and their welds, are generally very sensitive to HE. This paper deals with the first part of this study, involving the characterization of the microstructure and the mechanical properties of each zone of the electron beam weld (melted zone and four different heat affected zones), and the investigation of …

Mechanical properties and corrosion behaviour of low carbon martensitic stainless steel after machining

2014

The influence of different combinations of cutting conditions on the mechanical behaviour (microhardness), the microstructure and the corrosion behaviour in NaCl solution (using the electrochemical microcell technique and pulse potentiodynamic testing) of a low carbon martensitic stainless steel (grade X4CrNiMo16.5.1 stainless steel) after tempering treatment was studied. Microhardness was increased on the machined surface. In addition, the electrochemical experiments have shown that the machined materials have a heterogeneous electrochemical behaviour. Significant effect of machining on pitting corrosion was noticed. The pitting potential was found to decrease as the microhardness increase…

Influence of the microstructure on the corrosion behaviour of low-carbon martensitic stainless steel after tempering treatment

2014

Abstract The microstructure of grade X4CrNiMo16.5.1 stainless steel was studied at different scales. The chemical composition of the native passive film formed on the different phases was then determined at the microscale. The degree of homogeneity of the native passive film is discussed. Subsequently, the susceptibility to pitting corrosion of X4CrNiMo16.5.1 was quantified using the electrochemical microcell technique. The nature of precursor sites and the morphology of pits were investigated by combining scanning electron microscopy with Electron BackScatter Diffraction and potentiostatic pulse tests. The role of the microstructure and the cold-worked layer generated by polishing in pitti…

The phase diagram of Ti-6Al-4V at high-pressures and high-temperatures.

2020

Abstract We report results from a series of diamond-anvil-cell synchrotron x-ray diffraction and large-volume-press experiments, and calculations, to investigate the phase diagram of commercial polycrystalline high-strength Ti-6Al-4V alloy in pressure–temperature space. Up to ∼30 GPa and 886 K, Ti-6Al-4V is found to be stable in the hexagonal-close-packed, or α phase. The effect of temperature on the volume expansion and compressibility of α–Ti-6Al-4V is modest. The martensitic α → ω (hexagonal) transition occurs at ∼30 GPa, with both phases coexisting until at ∼38–40 GPa the transition to the ω phase is completed. Between 300 K and 844 K the α → ω transition appears to be independent of te…

A Dutch contribution to early interpretations of Meteor Crater, Arizona, USA – Marten Edsge Mulder’s ignored 1911 paper

2018

Abstract Following the first scientific descriptions in the late nineteenth century, the origin of the curious structure currently known as Meteor Crater (or Barringer Crater) in Arizona (USA) remained controversial until well into the twentieth century. Within the context of commercial mining, Daniel Moreau Barringer’s view that it recorded a substratum-penetrative meteorite impact (with the cosmic body still preserved) was commonly discarded. Marten Edsge Mulder (1847–1928), Dutch professor of medicine, found fault with Barringer’s non-explosive model. In 1911, Mulder advanced, in an ignored paper written in Dutch, a novel model of an explosive meteorite (‘meteor’ in Mulder’s terminology)…

Biological interactions in the boreal ecosystem under climate change : are the vole and predator cycles disappearing?

2014

Magnetic field effect on the corrosion processes at the Eurofer–Pb–17Li flow interface

2015

Abstract Structural and elemental analyses of the RAFM steel (EUROFER 97) interface with flowing Pb–17Li eutectic (velocity 5 cm/s at 550 °C, 1000 h) under the action of a strong magnetic field (B = 1.7 T) were performed using optical microscopy, SEM, confocal microscopy, precision micro-hardness methods, SIMS and point or line-scan EDX analyses. The results show that the magnetic field induces a faster crushing of martensite into the grains, a deeper dissolution of grain boundaries, an enhancement of the Fe and Cr mass transfer and a fast detachment of corrosion layers due to MHD effects.

Las guerras del agua

1997

Ferroelastic phase transitions of alkali halide-alkali cyanide mixed crystals

1990

Abstract The alkali cyanides and their CN-rich mixtures with alkali halides are proper ferroelastics with transitions from the cubic high temperature phase into the various non-cubic low temperature phases. As the CN concentration is reduced, the transformations temperature decreases and eventually the ferroelastic low temperature state is suppresse in favour of a glass-like state. The structural and elastic properties of these compounds are discussed with a special emphasis on the martensitic aspect of the transitions.

Polymorphism and the glasslike state of cyanide mixed crystals: A mesoscopic problem.

1990

The martensitic aspect of the structural phase transitions of the alkali cyanides and their solid solutions with the alkali halides is discussed. It is suggested that the polymorphism is intimately connected with the problem of mesoscopic transformation strains. At intermediate CN concentrations a competition between glasslike inhomogeneous strains, modulated strains, and ferroelastic strains is observed.