Effect of Simple and Combined Deformation on Mechanical Properties and Microstructure of Pure Molybdenum

The simple deformation in single tension, single compression, single torsion and the combined deformation in tension-torsion and compression-torsion of annealed pure molybdenum were tested. The uniaxial compressive response, microhardness test, fractography, microstructure and texture analysis were conducted to characterize the deformed specimen. The results of uniaxial compression test revealed that the yield strength of all samples was improved, but was much enhanced after compression-torsion test. The microhardness of all specimen increased gradually from center extending to the edge in cross section, except single tensile deformation specimen. However, microhardness increased the most during compression-torsion deformation. All the deformation modes induced refining effect on the grain size of pure molybdenum. Among all, the refining effect of tension-torsion and compression-torsion were more obvious, whereas the refining effect of compression-torsion was the best. This indicates that compressive stress increased cumulative ability of plastic deformation; therefore, the equivalent plastic strain of compression-torsion specimen before fracture is the largest.