Mechanical Behavior of Metal under Hydrostatic Pressure and Low Temperature

Abstract

The current work describes the behavior of metal under hydrostatic pressure and low temperature using finite element concept. This study was carried out in three stages: modelling, analysis and post processing. Structural steel and aluminum are tested at 600 bar pressure and 4°C temperature. Solid model of cylindrical shape having internal diameter 420 mm and thickness 25 mm was created and same was investigated for stress analysis using ANSYS 17.2 APDL emphasizing on hydrostatic behavior. Failure criterion is based on maximum stress to determine the onset of damage in material. In post processing phase, the material was checked for deformation and equivalent Von-Mises stresses developed around the material. The objective of this present paper is of two fold. Firstly the investigation of metal under high pressure through stress analysis is carried out followed by metallographic studies. The stress analysis results suggest that metals like steel which has BCC structure shows the remarkable decrease in ductility over the range of temperature. The maximum Von Mises stresses that the material can with stand were 65.14 MPa and 56.38 MPa for structural steel and aluminum respectively and revealed having high factor of safety for desired applications. It can be said that aluminum having FCC crystal structure are stiff and ductile even at low subzero temperature. The theoretical calculations are done and they are in agreement with the experimental results. It can be anticipated that influence of high pressure and low temperature can be criticized by two factors in terms of flow strength and fracture strength of metal. Ductile to Brittle Transition Temperature (DBTT) plays a vital role and can be considered as a measure of behavior of metal under high pressure and low temperature. So, it revels that the crystal structures of metals is the major factor which affects the behavior of metal which eventually affect the ductility and toughness of metal when subjected to high pressure and low temperature operations. However, in thick material the question of structural discontinuity and stress concentration is still regarded as open for further scope of study.