Friction Stir Welding Of Homogenous FRTP And Dissimilar,FRTP/Aluminum Alloy

At present, the technologies of adhesive bonding, machine riveting and fusionbonding are often used for the connection of FRTP and that of FRTP and aluminumalloy, but each has its limitations. In this paper, the technology of friction stir weldingis used for the welding of homogenous FRTP and that of FRTP and aluminum alloy.For friction stir welding of homogenous FRTP, the influence of welding processparameters on weld formation, micro-morphology and mechanical property wasinvestigated, and fracture was analyzed by SEM. For friction stir welding of FRTPand aluminum alloy, the influence of relative position of dissimilar materials, offsetand the plunge depth of shoulder on weld formation was investigated. The mainfindings were as following:Experiments of FRTP friction stir welding showed that: While plunge depth ofshoulder, rotational speed and welding speed matched each other, plastic material ofnugget could be fully plasticized and freely flow, and then good formation weld couldbe got; The results of the tensile property showed that: When the plunge depth ofshoulder was0.15mm, rotational speed was750r/min, welding speed was38mm/min,welded joints strength achieves maximum, up to45.56MPa, which was44.23%of thebase material strength. From the observation of the fracture cross section, jointbreaked between Advancing Side Thermal Mechanical Affected Zone and Nugget,which showed this area was the weakest of joint. SEM observations showed that,micro-fracture mechanism of the base material was carbon fiber fracture andinterfacial debonding of fiber and the matrix, micro-fracture mechanism of the jointwas the matrix shear fracture and interfacial debonding of fiber and the matrix.Experiments of FRTP and aluminum alloy friction stir lap welding showed that:While aluminum alloy was placed below, joint formation is poor, and effectiveconnection could not be obtained. While aluminum alloy was placed above, thebeautiful formation welds could be obtained. When the plunge depth of shoulder was0.16mm, rotational speed was750r/min, welding speed was30mm/min, welded jointsstrength achieves maximum, up to18.65MPa, which was71.46%of bonding strength.Fracture form of lap joint was shear fracture and fracture of the resin base material.SEM observations showed that micro-cracks existed in the interface. Experiments of FRTP and aluminum alloy friction stir welding showed that goodformation and effective connection joint could not be obtained.