Autofrettage is a process used in the manufacturing of pressure vessels and pipes to increase their strength and resistance to high pressure. It involves applying controlled internal pressure to the material, causing plastic deformation and compressive residual stresses on the inner surface.
Autofrettage is used to increase the strength, durability, and fatigue life of pressure vessels and pipes. It allows the material to withstand higher pressures without failure, making it a crucial process in industries such as aerospace, oil and gas, and nuclear power.
During autofrettage, the material is subjected to an initial elastic deformation, followed by plastic deformation. This causes the inner surface of the material to expand and the outer surface to contract. When the internal pressure is released, the material returns to its original shape, but with compressive residual stresses on the inner surface.
Autofrettage provides many benefits, including increased strength and fatigue life, improved resistance to stress corrosion cracking, and reduced risk of failure. It also allows for thinner and lighter pressure vessels and pipes, reducing costs and increasing efficiency.
There are two main types of autofrettage: hydraulic autofrettage and swage autofrettage. Hydraulic autofrettage involves using hydraulic pressure to deform the material, while swage autofrettage uses mechanical tools to expand the material. Both methods have their own advantages and are chosen based on the specific needs of the application.