1988 Volume 52 Issue 12 Pages 1293-1300
Three-point bending tests were carried out on the Ti-6Al-4V alloy specimens with various microstructures which were cathodically hydrogen-charged in the sulfuric acid solution, and the effect of hydrogen charging time on the bending strength and the deflection at maximum load was investigated.
The bending strength σb and the deflection at maximum load δmax of the specimens with granular primary α and either granular β or acicular α+β once decreased with increasing hydrogen charging time tc and showed a minimum at tc\doteqdot100 ks, then increased to reach a maximum at tc=150∼200 ks, and decreased again with further increasing tc. The specimens with acicular α+β structure hardly showed such a tendency, i.e. σb or δmax decreased gradually to a constant value with increasing tc. Hydride thickness BH increased monotonically with increasing tc and the BH was larger in the specimens with granular α+β than in those with acicular α+β. The main reason for the appearance of maximum in σb and δmax seemed that the residual compressive stress near specimen surface caused by the expansion of the α phase during its transformation to hydride cancelled out the tensile stress at bending tests.
