Influence Study of the Plastic Deformation Mode on the Micro-Indentation Mechanical Properties for the Pure Molybdenum

Four different plastic deformation modes of pure molybdenum in powder metallurgy were studied, including single tensile, single torsion, tensile-torsion and compressive-torsion. Then the influence of these four plastic deformation modes on the micro-mechanical properties of pure molybdenum in powder metallurgy was studied by the micro-indentation method. The results show that the accumulated strain before deformation instability or fracture of the studied material caused by different plastic deformation modes is different, while showing a regular variation. And the mean indentation hardness along the radial direction of the sample also change regularly, which results in different strengthening effects on the molybdenum material itself. The damage inside the deformed material will cause the apparent modulus of elasticity measured by micro-indentation to decrease significantly.

Finite Element Analysis of Large Plastic Deformation Process of Pure Molybdenum Plate During Hot Rolling

Rare molybdenum resources have been increasingly involved in heavy industries. In this paper, the common unidirectional and cross hot rolling operations, for pure molybdenum plate, are numerically simulated by using MSC. Marc software. An elastic-plastic finite element model is employed together with updated Lagrange method to predict stress and strain fields in the work-piece. The results showed that there was a typical three-dimensional additional compressive stress ( σy > σx > σz ) in deformation zone, while strain could be divided into uniaxial compressive strain and biaxial tensile strain ( Ey > Ex > Ez ). Tensile stress σx increased with the accumulation of reduction and the decrease of friction coefficient at the edge of width spread. More importantly, the interlaced deformation caused by cross commutation was helpful to repair the severe anisotropy created by unidirectional hot rolling. By comparing the theoretical verification of rolling forces and the measured temperatures with the simulated values, eventually, it is demonstrated that the model is aligning well with the actual engineering.