Electrochemical Fatigue Sensor
The technology behind EFS was originally devised by researchers for the U.S. Air Force and the University of Pennsylvania for use in the aerospace industry. The original research was aimed at developing a technology for detecting problem cracks in airframes and engines. Grade 5, also known as Ti6Al4V, Ti-6Al-4V or Ti 6-4, is the most commonly used alloy in the aerospace industry, e.g. internal combustion engine connecting rods.
It has a chemical composition of 6% aluminium, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium. It is significantly stronger than commercially pure titanium while having the same stiffness and thermal properties (excluding thermal conductivity, which is about 60% lower in Grade 5 Ti than in CP Ti).
Among its many advantages, it is heat treatable. This grade is an excellent combination of strength, corrosion resistance, weld and fabricability. Generally, it is used in applications up to 400 degrees Celsius.
(Grade 5 has a density of approximately 4420 kg/m3, Young’s modulus of 110 GPa, and tensile strength of 1000 MPa. By comparison, annealed type 316 stainless steel has a density of 8000 kg/m³, modulus of 193 GPa, and tensile strength of only 570 Mpa and tempered 6061 aluminium alloy has a density of 2700 kg/m3, modulus of 69 GPa, and tesnsile strength of 310 MPa.)