ENHANCING HIGH-TEMPERATURE OXIDATION RESISTANCE OF TITANIUM ALLOY WITH KF110-B4C-Ag THROUGH LASER TECHNOLOGY

In this paper, the high-temperature oxidation resistant coating on the TA15 titanium alloy by laser cladding (LC) of the KF110-B4C-Ag mixed powders was analyzed in detail. The scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS) images indicated that a good metallurgy bond between the fabricated coating/TA15 was formed; also the fine/compact microstructure was produced after a cladding process. The oxidation mass gain of TA15 was higher than that of the coating after LC process, which were 3.72 and 0.91[Formula: see text]mg[Formula: see text]cm[Formula: see text], respectively, at 60[Formula: see text]h, greatly enhancing the high temperature oxidation resistance.

High-Temperature Oxidation Behaviors of TA15 Titanium Alloy after Mechanical Grinding and Laser Cleaning

This paper presents the results of a study on the high-temperature oxidation characteristics after mechanical and laser removal of TA15 titanium alloy oxide film. The morphology, components, and roughness of the surface were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and laser confocal microscope (OM). The oxide film can be effectively removed with mechanical grinding and laser cleaning, and the oxide film after mechanical grinding is thicker and looser than that of after laser cleaning. The oxide film is principally composed of TiO2, Ti2O3 and TiO. Besides, there is a small amount of aluminum oxide on the surface. The surface after mechanical grinding was rougher than that of after laser cleaning. Thus, this work indicates that laser can not only clean the oxide film completely, but also strengthen the surface, which is a promising way to favor the widespread application of laser cleaning technology.

Effect of Laser Welding Speed on Grain Morphology and Tensile Property of TA15 Titanium Alloy Bottom-Locking Joint

The laser welding of TA15 titanium alloy with the bottom-locking joints is carried out by TruDisk-12003 disc laser. In this paper, the microstructure and tensile properties of welded joints with different welding speeds are studied. The microstructure is observed by optical microscope. The tensile fracture morphology and chemical composition are analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) respectively. The experimental results show that the width of weld zone (WZ) is decreased significantly with the increasing of welding speed. The β columnar crystal shows respective morphology and growth direction in WZ under different welding speeds, meanwhile, the number of acicular martensite which is precipitated in columnar crystal also presents different. Besides, the aggregate growth zone of columnar crystal at the bottom of weld zone gets smaller with the increase of welding speed. The maximum tensile strength for the TA15 titanium alloy bottom-locking joint, which is fractured at weld joint, reaches 89% of the BM. Besides, the EDS results illustrate that the burning loss of stabilization element is inevitable.

Spatial and Direction-Based Characterization of Microstructures and Microhardness of TA15 Titanium Alloy Produced by Electron Beam Melting

The extracted position and characterization direction of specimens have an unignorable effect on the microstructural characteristics of materials produced by electron beam melting (EBM). This study focused on the effects of extracted position and characterization direction on the microstructure, defect distribution and Vickers hardness of TA15 titanium alloy fabricated by electron beam melting. Results show that the microstructure at the bottom end of TA15 specimens is coarser and hot cracks are visible at this end. Grain morphology in longitudinal direction is columnar while that in transversal direction is chessboard-like. The results of defect analysis show that gas pores are visible in transversal direction while lack of fusion exists in longitudinal direction. The average relative density of TA15 specimens in transversal direction is higher than that in longitudinal direction. The results of energy spectrum analysis show that there is evaporation of Al during the forming process, but no elements segregation and enrichment are observed. This study provides important insights on the microstructure analysis and defect evaluation of materials made by EBM technology.