EXFOLIATION CRACKING ANALYSIS OF WATER-COOLING TUBE

A comprehensive analysis which is based on chemical composition,optical microstructure,microhardness,tensile strength was made on the exfoliation cracking of water-cooling tube. The results showed that the hardness at the break was much higher than the hardness of matrix material. The matrix microstrucutre was made up of ferrite and pearlite which did not spheroidize obviously but the microstructure near break was made up of ferrite,pearlite and bainite which was the microstructure of sub-temperature quenching. The above results indicated that the exfoliation cracking of water-cooling tube was mainly caused by short-time sudden overheating which made the strength of the matrix material decrease dramasticaly and induced the exfoliation cracking of the tube.