Cracking Analysis on Steering High Pressure Oil Pipe of Heavy Trucks

Cracking occurred in steering high pressure oil pipe of a heavy truck in the process of driving. By means of chemical composition analysis, metallographic examination, fracture analysis, hardness testing and so on, the cracking reason of oil pipe was analyzed. The results showed that there were two scratches on the inner surface of cold drawn pipe, about 1 mm away. The crack initiation formed at the bottom of one scratch, with stress corrosion in the process of surface treatment. The crack extended under compressive stress of high pressure oil in the process of driving, and led to cracking in oil pipe.