Grade 5 Hex Tap Bolts are made from AISI 1030-1541 or equivalent medium carbon steel. Commonly used to mount motors to machinery and are also popular in automotive and truck repair. Rockwell C25-C34. Proof load - 85,000 psi. Yield Strength - 92,000 psi. minimum. Tensile Strength - 120,000 psi. minimum.Porteous Fastener Company