Titanium elbow parts of the cold push-bending process is the production of such parts is quite economical, efficient process method, has a fairly important value of engineering applications. A study for the enterprise production of push-bending cracking problems, excluding the mold and push-bending machine suspected that the research point on the preparation of heat treatment process route to improve the plastic deformation capacity of the billet. Through the study, the following main conclusions were reached.
(a) The influence of heat treatment process on the microstructure and mechanical properties of C276 alloy was studied. The use of different process parameters on the pipe billet heat treatment, the microstructure of the sample, mechanical properties and other analyses, the results show that: the use of 1120 ℃ × 0.5h + 850 ℃ × 0.5h heat treatment method is more reasonable, after heat treatment, the sample microstructure of precipitates have not yet formed a chain-like structure, and dislocation lines within the grain is significantly reduced, the material elongation of 66%, yield strength of 348MPa, significantly reduced, the material elongation of 66%, and the yield strength of 348MPa. The material elongation is 66%, and the yield strength is 348MPa, which obviously improves the plastic deformation ability of the alloy.
(ii) Through the analysis of the microstructure and phase composition of the cracked titanium elbow, it is found that there are a large number of intergranular precipitates distributed in a chain-like manner at the crack, and the precipitates are mainly u-phase and M6C, which are brittle phases, and the existence of brittle phases leads to the formation of microcracks in the process of cold bending of the material is easy to form microcracks, and with the continuation of the force, the microcracking of the sharp corners of the occurrence of the phenomenon of stress concentration, which makes the expansion of microcracks, and the expansion along the Chain-like brittle cross-section of the grain boundary extension terminal fracture, so that the plasticity of the alloy will be greatly reduced.
(C) the use of different push-bending speed on the titanium elbow cold push-bending experiments, cold push-bending pressure of 25MPa, lubricant for MoS2. after heat treatment of the pipe bad in the push-bending process did not occur cracking phenomenon, different push-bending speed (3.5mm/s-5mm/s) conditions of the C276 alloy of the outer arc of the thinning rate of 7.5% -8%, through comparison found that, in the 4mm/s push-bending speed, the C276 alloy of the external arc of 7.5% -8%, through comparison found that, in the 4mm / s of the By comparison, it is found that at 4mm/s bending speed, the wall thinning rate of C276 alloy is only 7.5%, which is better than the wall thinning rate of samples at other bending speeds.
