Variations in strain affect friction and microstructure evolution in copper under a reciprocating tribological load

The microstructure of the materials constituting a metallic frictional contact strongly influences tribological performance. Being able to tailor friction and wear is challenging due to the complex microstructure evolution associated with tribological loading. Here, we investigate the effect of the strain distribution on these processes. High-purity copper plates were morphologically surface textured with two parallel rectangles—referred to as membranes—over the entire sample length by micro-milling. By keeping the width of these membranes constant and only varying their height, reciprocating tribological loading against sapphire discs resulted in different elastic and plastic strains. Finite element simulations were carried out to evaluate the strain distribution in the membranes. It was found that the maximum elastic strain increases with decreasing membrane stiffness. The coefficient of friction decreases with increasing membrane aspect ratio. By analyzing the microstructure and local crystallographic orientation, we found that both show less change with decreasing membrane stiffness

Microstructure and mechanical behavior of deep drawing DC04 steel at different length scales

The deformation behavior of steels is strongly influenced by their microstructure which is a result of the alloying elements and thermal treatments. In this work, the microstructure and the deformation behavior of a non-alloyed deep drawing DC04 steel was investigated. The microstructure was analyzed during heat treatment by EBSD, then microcompression experiments were performed on selected microstructural units and then bulk steel samples were mechanically tested by tensile experiments