Formation of Alpha-Case Layer during Oxidation of Ti6Al4V Surface by Annealing at 1050 °C and Change of Microstructure after Different Cooling Rates

• DOI: 10.4028/p-r71e1w
• Publication Date: 2023-03-24T14:29:47Z
• Authors: Juraj Belan; Milan Uhríčik; Lenka Kuchariková; Eva Tillová; Lucia Pastierovičová
• Keywords: Charpy impact test; Titanium alloy; Surface layer

The two-phase titanium alloy Ti6Al4V (often referred to as GRADE 5 or Ti64) is currently probably the most widely used type of Ti alloy. It characterized by an excellent combination strength - toughness chemical stability. However, at temperatures above 500 800 °C it prone diffusion oxygen into surface layers, where increased content creates so-called “alpha-case” layer. formation this layer associated with a reduction mainly in deformation characteristics paper focuses on metallographic analysis "alpha-case" after annealing 1050 holding time 3 hours and cooling different rates (500 °C/s, 1 °C/s 0.08 °C/s). Microstructure changes were observed light microscopy using polarized – PL, dark field DF phases identified SEM methods. influence microstructure mechanical properties was determined measuring microhardness HV0.2 /10 (STN EN ISO 6507) Zwick / Roell ZHµ resistance impact stress KU (Charpy system STN 10045-1). Based measurement, increase layers all same time, decrease compared initial state.