Effect Of Service Temperature On Microstructure Of TA2/Q235 Explosive Welding Composites And Fractal Characterization Of Shear Fracture

Explosive welding composite materials are widely used in the manufacture of corrosion-resistant containers and equipment due to their excellent performance and low cost,and have been widely used in aerospace,petroleum,chemical,military and other fields.This composite material will be subjected to severe detonation shock during the welding process,resulting in different degrees of plastic deformation.There is a large amount of residual stress inside the weld,and the stress corrosion will cause the joint zone to crack during the service.The shear strength of an explosive composite panel is typically used to judge its bond strength.It can be seen that the study of the shear behavior of explosive composites during service is an important issue.In this paper,the TA2/Q235 explosive composite plate is taken as the research object,and the influence of annealing process on the microstructure and properties of the composite plate is discussed.The service life of the composite plate is studied by heat treatment to simulate the service temperature,and the service theory is established by using fractal theory.The relationship between the mechanical properties of the material shear fracture and the fracture morphology.The main research contents and conclusions are as follows:(1)After the TA2/Q235 explosive composite board was annealed at different temper-atures and times,the best annealing process was determined to be 575 ℃ for 1 h by observing its microstructure and properties.(2)Simulating the service temperature by heat treatment,the results of microstructure,microhardness and shear test indicate that the service temperature should be below 600 ℃,otherwise it will easily cause a rapid decline in the mechanical properties of the joint zone.(3)Through the observation of the shape of the shear fracture,it is pointed out that the TA2/Q235 shear fracture has the characteristics of ductile fracture,quasi-cleavage fracture and cleavage fracture.At 200 ℃,the ductile fracture and quasi-cleavage fracture morphology will change to cleavage fracture morphology;there is no obvious change at 400 ℃ service;the cleavage fracture morphology develops to ductile fracture morphology at 600 ℃ service.(4)Using Matlab to perform binarization and fractal operation on the scan fracture morphology,the fracture fractal dimension has only a qualitative relationship with the shear performance.The fracture fractal dimension increases with the shear strength decrease,and the fractal spectrum span difference There is a negative correlation linear relationship with shear strength.