Study On The Interface Mechanical Properties Of Metallurgical Composite Bimetallic Tube

Metallurgical composite bimetallic tube is completely a new product, which producted by non-plastic molding and combines the primary industry materials with a high technical metallurgical treatment process. The centrifugal casting tube blank is producted by extruding, cold rolling or cold drawing, and then high quality composite tube is obtained. This kind of composite tube may be the binding between common carbon steel and stainless steel, or the binding between common stainless steel and high quality stainless steel, or the binding between any steel and Ni, Cr, Mo alloy, and also, the bindings of multi-layers metals upon customers’requests. Metallurgical composite bimetallic tube can be widely used in petroleum, chemical, offshore platforms and other highly corrosive environment, through the inner composite wear-resistant metal; it can also meet the power plant pulverized coal mine slag and tailings slurry transport high-wear work environment requirements.Based on the metallurgical composite bimetallic tube X60/Incoloy825, the J-integral and HRR field theory were described in the crack-tip field, and then the singular stress field was analysised near the crack tip and the fracture criterion was judged. Secondly, the hardness, impact toughness and the basic mechanical parameters of the metallurgical composite bimetallic tube X60/Incoloy825were measured in the laboratory. Thirdly, it can be seen from the microstructure observation and tensile fracture SEM of the metallurgical composite bimetallic tube X60/Incoloy825that the metallurgical composite bimetallic tube has a stronger bonding strength between the internal and external layer and the interface have achieved completely a metallurgical bonding. Forthly, through the finite element analysis software ABAQUS. the stress distributions of the metallurgical composite bimetallic tube X60/Incoloy825in elastic state, elastic-plastic state and plastic state were obtained, and then the limiting inner pressures in plastic state were obtained. Comparing with the external metal tube X60. the limiting inner pressure of the metallurgical composite bimetallic tube has increased more than two times because of the transition layer which has a complete metallurgical bonding. Fifthly, through the finite element analysis to the arch three-point bending specimens of the metallurgical composite bimetallic tube X60/Incoloy825, the dynamic fracture process and the J-Δa curves were obtained. Meanwhile, the changing process of the fracture intensity factor K1with the crack propogation was obtained, and then the fracture toughness was calculated. Through the calculation of fracture toughness, it can be used to evaluate the bearing capacity of the cracked bimetallic tube. Meanwhile, it also can be used to evaluate the maximum crack size of bimetallic tube in a certain working stress. This method provides a viable standard for the quality acceptance of the similar bimetallic tube.