Performance of nano-structured multilayer PVD coating TiAlN/VN in dry high speed milling of aerospace aluminium 7010-T7651

A low-friction and wear resistant TiAlN/VN multilayer coating with TiAlN/VN bilayer thickness 3 nm has been grown by using the combined cathodic arc etching and unbalanced magnetron sputtering deposition on high speed steel tools for dry cutting of aluminium alloys. In this paper, in-lab and industrial high speed milling tests have been performed on an aerospace aluminium alloy 7010-T7651. The results show that the TiAlN/VN coated tools achieved lower cutting forces, lower metal surface roughness, and significantly longer tool lifetime by three times over the uncoated tools as a result of the low friction and eliminated tool-metal adhesion. Under the same conditions, a TiAlN based multicomponent coating TiAlCrYN also increased the tool lifetime by up to 100% despite the high cutting forces measured

Evolution of microscopic strains, stresses, and dislocation density during in-situ tensile loading of additively manufactured AlSi10Mg alloy

The AlSi10Mg alloy produced by laser powder bed fusion (LPBF) possesses a novel microstructure and higher mechanical properties compared with its casting counterpart. So far, the crystallographic orientation-dependent lattice strains, average phase stresses, and dislocation density during the tensile loading of the LPBF AlSi10Mg are not well understood. This fact is impeding further optimization of microstructure and mechanical properties. High energy synchrotron X-ray diffraction providing deep penetration capability and phase-specific measurements of various bulk properties of crystal materials is applied to investigate the LPBF AlSi10Mg under loading. The crystallographic orientation-dependent lattice strains and elastoplastic properties of the Al matrix are assessed. The average phase stresses are calculated to quantify load partitioning between the Al and Si phases. The nano-sized Si particles that bear high-stress are efficient strengthening particles. The maximum value of the average phase stress of Si reaches up to ~2 GPa. Based on the modified Williamson-Hall and the modified Warren-Averbach methods, the dislocation density and its evolution during the plastic deformation are determined. A multistage strain hardening behavior is detected in the Al matrix, which is associated with the interactions between the dislocations and the cell boundary network

An additively manufactured and direct-aged AlSi3.5Mg2.5 alloy with superior strength and ductility: micromechanical mechanisms

An AlSi3.5Mg2.5 (wt%) alloy with excellent mechanical properties was produced via laser powder bed fusion in this study. The yield strength, tensile strength, and elongation of this as-built AlSi3.5Mg2.5 alloy reach about 406 MPa, 501 MPa, and 8.6%, respectively. These properties are dramatically superior to the current additively manufactured Al-Si-Mg alloys. A direct-aging treatment at 170°C for one hour increases the yield strength and ductility further to about 417 MPa and 11.0%, respectively, with the tensile strength remaining the same level. The microstructures and strengthening mechanisms of the as-built and direct-aged samples were investigated systematically. The underlying micromechanical mechanisms of the as-built and direct-aged samples were examined based on a combination of in-situ synchrotron X-ray diffraction and three-dimensional crystal plasticity modeling. The as-built AlSi3.5Mg2.5 alloy possesses a fine microstructure, including fine grains and nano-sized Mg2Si and Si precipitates. After direct-aging treatment, additional Mg2Si and Si precipitate out. Besides, element diffusion upon aging treatment causes migration of cell boundaries and relaxation of residual stress. The direct-aging treatment leads to an increased Orowan strengthening, dislocation strengthening, and load-bearing strengthening effects. Moreover, the variations of microstructure and residual stress after the aging treatment change the dislocation behavior and increase the dislocation storage capacity, causing an increased ductility. Nevertheless, the aging treatment does not alert the type of damage and fracture. This study provides valuable insights to tailor the microstructure and mechanical properties of additively manufactured Al-Si-Mg alloys

CVD-Diamantbeschichtung von Stahl Abschlussbericht

SIGLEAvailable from TIB Hannover: F97B2089+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman