The Influence of Hydrogen on Thermal Desorption Processes in Structural Materials

AbstractHydrogen embrittlement is a form of environmentally assisted failure caused by the action of hydrogen, often in combination with residual or applied stress that results in a reduction in the load-bearing capacity of a component. It was found that hydrogen has a direct influence on the lattice parameter and on the thermal expansion characteristic. Hydrogen's desorption behavior in this process and its effects on the mechanical behavior of those materials are discussed in detail

Time resolved Bragg edge neutron radiography for observing martensitic phase transformation from austenitized super martensitic steel

Neutron Bragg edge imaging was applied for the visualization of a amp; 947; austenite to amp; 945; amp; 8242; martensite phase transformation. In the present study, a super martensitic stainless steel sample was heated until complete austenitization and was subsequently cooled down to room temperature. The martensitic phase transformation started at Ms 190 C. Using a monochromatic neutron beam with amp; 955; 0.390 nm, the transmitted intensity was significantly reduced during cooling below Ms, since the emerging martensitic phase has a higher attenuation coefficient than the austenitic phase at this wavelength. The phase transformation process was visualized by filming the transmission images from a scintillator screen with a CCD camera with a temporal resolution of 30 s and a spatial resolution of 100

Energy selective neutron imaging by exploiting wavelength gradients of double crystal monochromators simulations and experiments

The potential of wavelength resolved neutron transmission experiments is well known. This paper is focused on the performance of the double crystal monochromator which is widely used at steady state neutron sources and compares simulation results based on neutron ray tracing with experimental results in order to provide a better understanding of the device. The influences of crystal mosacities on the neutron beam is reported for the utilised setup and the resulting wavelength gradients along one direction are determined. For the neutron imaging geometry applied, a wavelength gradient of about 0.005 cm at the sample position was found. Moreover, a new neutron radiography technique for Bragg edge mapping in imaging experiments utilising a neutron wavelength gradient at the sample position was developed and is reported. Experiments and simulations are found to be in good agreemen