The Analysis Of 2A12 Alloy MIG Weldorganization Refinement Mechanism With Titanium And Zirconium Refinement

2A12 belongs to Al-Cu-Mg Aluminum Alloy, is a typical aluminum alloy, has excellent mechanical properties and comprehensive. Widely used in the field of building structure, aerospace, transportation, a large number of used to manufacture aircraft on the skin, skeleton parts, frame, rivet, wing rib, wing beam and other parts of the bearing force. Live on the properties of 2A12 aluminum alloy wave, good thermal conductivity, expansion coefficient. In the process of welding prone to welding deformation, surface oxidation, generation of welding hot crack, welding joint softening zone width, low intensity, poor ductility and fatigue performance, structure easy to failure, of the alloy structural parts are used.This paper on the basis of traditional er2319 welding wire composite addition of different content of Ti, Zr elements, The influence of different Ti and Zr content on Microstructure and properties of 2A12 aluminum alloy MIG welding seam was studied, and the mechanism of Ti and Zr composite refining 2A12 aluminum alloy welding seam was studied. Firstly, the influence of different parameters on the formation of welding seam is analyzed by orthogonal test. By the electronic universal tensile machine, hardness tester in testing the mechanical properties of different weld, and the use of optical microscopy(OM), scanning electronic display ceramics(SEM), transmission electron microscopy(TEM) on weld microstructure and the second phase particles were observed, and by X-ray diffraction(XRD), spectrometer(EDS) of the weld, phase composition and weld elements distribution were analyzed. At the same time by differential scanning calorimetry(DSC) of different wire welding melting point measurement, enthalpy and the nucleation reaction temperature, and achieved the following research results:Influence factors of weld pool width according to the order of the Lord, welding speed, welding current, welding voltage, welding wire are; on the weld residual high impact factors in the main to order is: welding current, welding wire, welding voltage and welding speed. The welding current is 50 A, the welding voltage is 18 V, the welding speed is 900 mm.min-1 when the weld is formed on the surface of the best.The refinement effect of Ti and Zr elements on the weld of 2A12 aluminum alloy is compatible. With the wire in Ti, Zr content increased, the finer the grain size of the resultant weld and weld in a α(Al) + theta β eutectic structure by continuous network distribution is a diffuse granular distribution and eutectic microstructure became finer.The refinement effect of Ti and Zr elements on the weld of 2A12 aluminum alloy is compatible. With the wire in Ti, Zr content increased, the finer the grain size of the resultant weld and weld in α(Al) + β eutectic structure by continuous network distribution is a diffuse granular distribution and eutectic microstructure became finer.In the welding seam of the E4 wire welding internal crystal found Al3 Ti, Al3 Zr particles, also found that two particles wrapped together particles, particles of Al3 Ti in inner layer, Al3 Zr particles will be wrapped in the internal, α(Al) process, a part of Al3 Ti and Al3 Zr particles and molten aluminum occurred peritectic reaction. Another part of the Al3 Zr Al3Ti particles will be wrapped, and then place the peritectic reaction of aluminum melt.