Wednesday, 18 April 2018

Cracks in the pipe

The cracks in the austenitic stainless steel sample on the picture below are most likely a case of Stress Corrosion Cracking (SCC). SCC is the cracking induced from the combined influence of tensile stress and a corrosive environment (such as chlorides). The impact of SCC on a material usually falls between dry cracking and the fatigue threshold of that material. The required tensile stresses may be in the form of directly applied stresses or in the form of residual stresses. The problem itself can be quite complex.

Thursday, 5 April 2018

Old but indispensable

A polarization microscope can be used to identify the mineralogical composition of geological materials in order to help reveal their origin and evolution. Some of the properties and techniques used include: refractive index, birefringence, Michel-Lévy interference color chart, extinction angle, conoscopic interference pattern (interference figure), Becke line test, wave plate etc.