Larry-HCENG
Materials
We just received a batch of titanium wires of grade 5 (Ti-6Al-4V). The surfaces are covered by a layer of black & oily substance which can be readily wiped off by a piece of cloth. After wiping, the titanium appears in tan/bronze color. Please see the attached photo. I wonder what the substance is and what kind of surface treatment may result in such appearance? By the way, the titanium wires are imported from EU which are used for bolt fabrication.