.5 The A30 Preparation Technique Of With Tendons Wide Aluminum

The deformation behavior of 5A30 aluminum alloy at high temperatures was investigated by isothermal compression testing method with Gleeble-1500 thermal simulator, and material constants of 5A30 aluminum alloy during high temperature deformation were calculated by regression analysis; The extrusion process was numerically simulated with the finite element software HyperXtrude. With numerical simulation, the velocity and deformation of profiles and die stress distribution were analyzed, and the design parameters of die structure were optimized; Refer to extrusion process simulation results, combined with extrusion tests, the extrusion process of 5A30 wide ribbed aluminum profiles were studied, and the Optimal extrusion process parameters were obtained; By means of slow strain rate tensile(SSRT), OM, SEM and TEM, the effects of the pre-deformation on stress corrosion and exfoliation corrosion performance of 5A30 wide ribbed aluminum profiles were studied, and the microstructure of which under different pre-deformation condition were analyzed. The main results of the thesis were showed as follow:1. A steady plastic flow of the 5A30 aluminum alloy was confirmed during isothermal compression deformation in the range of 300～450℃and 0.001～1.0s-1. The flow stress increases with decreasing deformation temperature and increasing of strain rate, the strain values into steady plastic flow state increase corresponding. Indicating 5A30 aluminum alloy is strain rate positively sensitive materials, the influence of temperature on flow stress than the strain rate on flow stress is more evident.2. A thermal activation process of the 5A30 aluminum alloy was confirmed during isothermal compression deformation, the interrelations of flow stress, strain rate and deformation temperature can be described by a hyperbolic sine function. The material constants of 5A30 aluminum alloy during high temperature deformation were calculated by minimum deviation method, A=9.94×1010s-1,α=0.0119mm2/N, n=4.677, Q=162.3kJ/mol, the flow stress model can be expressed asσ= 68.96ln{[Z/(9.94×1010)]1/5.439+{[Z/(9.94×1010)]2/5.439+1}1/2}. 3. Aluminum alloy flows slow in the diversion holes, When aluminum alloy flowed into welding chamber through diversion hole with uneven distribution of velocity, which lead to uneven flow profile and partial wall and deformation profiles; The maximum stress of diversion die was distributed on Surface location of die, the maximum stress was 939Mpa, the maximum stress of die was distributed at cantilever position, the maximum stress was 1314Mpa.4. After the structure optimization of diversion model and Die Bearing, the velocity of profile is balanced and the deformation decrease; Deformation of trial material agreement with the simulation, the quality of trial material reached standard, meets the requirements of design. The optimal extrusion process parameters of 5 A30 wide ribbed aluminum profiles are: Ingot temperature(460-480℃), die temperature(470℃), extrusion Container temperature(440-460℃), extrusion temperature(480-500℃), extrusion velocity(2-4m/min).5. Pre-deformation in the range of 0～15%, with the increase of pre-deformation, the ISSRT values of 5A30 wide ribbed aluminum profiles decreased first and increased afterwards, when pre-deformation for 10%, the ISSRT value is the smallest; when pre-deformation for 0, the SSRT fracture morphologies in 3.5% NaCl solution showed homologous-cleavage characteristics, with the increase of pre-deformation, the brittle fracture features decreased first and increased afterwards, when pre-deformation for 10%, brittle fracture features are the smallest, with the increase of pre-deformation, the SCC susceptibility of 5A30 aluminum profiles decreased first and increased afterwards.6. The influence of Pre-deformation on exfoliation corrosion performance is similar to that on stress corrosion performance of 5A30 wide ribbed aluminum profiles. When pre-deformation for 0, the EA class exfoliation corrosion occurred, with the increase of pre-deformation, the resistance to exfoliation corrosion enhanced, when pre-deformation for 10%, the phenomenon of pitting and exfoliation corrosion didn't appear, with the pre-deformation increased continually, the resistance to exfoliation corrosion declined, when pre-deformation for 15%, the PB class pitting corrosion occurred. 7. When 5A30 aluminum profiles without pre-deformation, dislocation density are low, grain boundaryβ-phase distributes continuously on the local scale; when pre-deformation increases to 10%, dislocation density increases, and grain boundaryβ-phase distributes discontinuously; when pre-deformation increases to 15%, dislocation movement is blocked, result in a large number of dislocation tangles, and internal stress increases, grain boundaryβ-phase distributes continuously on the local scale.