Thermal simulation of high temperature deformation of Al-Fe-V-Si alloy

Journal of Central South University of Technology Li Wenxue, Yang Junjun, Xiao Yude Department of Materials Science and Engineering, Central South University of Technology, Changsha 410083, Hunan, China Abstract: With 150 pairs of thermal simulation pairs, the alloys at the temperature drop 泠 35,55, and the speed change is 041028 maximum deformation degree of 50 conditions, high-temperature compression thermal simulation experiments. Based on the experiment, the deformation activation energy and stress exponent, rheological change and enthalpy change of the alloy at high temperature were analyzed. Deformation temperature of the network, to determine the extrusion temperature of the alloy to provide a total of experimental basis. The experimental results show that the payoffs have high sensitivity and deformation activation energy, while 1 has lower deformation resistance at 48,1. The product can have good mechanical properties after extrusion. therefore. It can be considered that the extrusion temperature is set at about 1 key key. , 1.1 alloy pressure 拽-shaped rheological deformation of the activation energy in the classification number D; 142.6 rapid solidification 1 heat-resistant error alloy is a kind of aerospace for the new aluminum alloy, high strength, good heat resistance, low density, Low cost and good development prospects. However, the plasticity of the alloy is low, and the deformation resistance is large. Therefore, whether or not the molding can be processed is the key to the promotion and application of the alloy. At present, domestic and foreign scholars have rarely studied this issue. For this reason, the author studied the high-temperature deformation characteristics of the alloy by investigating the relationship between the high temperature flow stress and strain rate deformation temperature and deformation degree.

1 experimental program After the pressure on the billet longitudinal interception, turning into a small parent 9 father 12 high cylinder, both ends of the compression evenly coated with lubricant 75 graphite +25 engine oil, mass fraction, the same to reduce friction. The compression experiment was performed on a 01,500 thermal simulator. The heating speed is the holding time. In order to deform the instantaneous water-sweat, the maximum deformation degree is 50, the deformation temperature is 350,400,450,500,550, and the strain rate is 2.77 2.771. All the mountain juice machines in the deformation process are controlled and the motion is collected. data.

2 Experimental results and analysis The experimental materials were obtained from the non-equilibrium material research institute of Central South University of China. The outer diameter of the 6501 inner diameter was 360 tubes and the 480 was extruded. The extrusion ratio was 4 and the chemical composition was , 18.5.31.751. Card specimens from the extrusion 2.1 true stress true strain curve true strain curve 1.

Fund Projects National Science and Technology Key Projects Funded Projects 95 Scholars 010 About the Author Leigh Literature 193. Male. Professor of Central South University of Technology, doctoral tutor.

From 1 it can be seen that the flow stress of the alloy increases to a certain peak with increasing degree of deformation at high temperature, and then slowly decreases. The alloy appears bright from the softening phenomenon. This can be explained from the following aspects: 1 Because the experimental village material is made by jet deposition techniques, the grain size is relatively small and does not exceed 25,1. The slip distance is of the same order of magnitude and therefore the inter-grain dislocations are cut short and the dislocation density is low, resulting in the disappearance of the hardening effect caused by the intersection of dislocations. When the material is deformed at a high temperature, precipitation of the precipitated phase and change of the texture of the roughened phase transition may also cause the material to soften. For people 1 mediation. The precipitation phase 412 during the heat-shrinking deformation will coarsen the clothes and partially convert them into harmful phases 164 under certain conditions, resulting in rheological softening of the material. Recrystallization 2, therefore, dynamic, complex and dynamic recrystallization may also be the cause of the high-temperature rheology softening of the combined deuteration; 1 due to the deterioration of the lubrication conditions during high-temperature compression deformation, uneven deformation due to friction may also cause The high temperature rheology of the gold melts.

22 strain rate impact on flow stress strain rate rhythm should be one of the important factors. From the increase of the strain rate with the increase of the strain rate, the bright material is a positive strain rate sensitive material. This is mainly because the larger the strain rate, the less the plastic deformation is performed, the more the elastic deformation is, and the flow stress is larger and larger. . In the research bureau's temperature change, it was found that the highest point of the steady-state flow stress and even the peak stress true stress true strain curve satisfies the following relational temperature, 7. They are all material constants.

Through the regression analysis of the experimental data, take 0.067 MPI. Deformation private degree, 81 such as. Another example is the tower 27 to take the peak stress. Yes, the two are in a good linear relationship. However, at different temperatures, the slope of the line is different, indicating that the activation energy of deformation changes with changes in temperature.

2.3 Influence of Temperature on Flow Stress Temperature is a very important factor affecting flow stress.

3 Court 1 can be seen under a speed change book. True stress levels decrease with increasing temperature. Because as the temperature increases, the effect of thermal activation increases, the kinetic energy between atoms increases, and the critical shear stress between atoms decreases. In addition, the degree of softening caused by dynamic, complex, and dynamic recrystallization also increases with increasing temperature, which leads to a reduction in the stress level of gold.

When the strain rate is constant, it is assumed that the deformation activation energy 2 remains unchanged in a very small temperature range. The material constant can be obtained by taking the logarithm of both sides of the equation. Substituting the experimental data into 3 formulas can be used to draw the relationship such as 1 and 3. From 3, we can see that the two are in a good linear relationship, but at different strain rates, the slopes of the straight lines are different, indicating that the deformation activation energy Change with strain rate.

2.4 Stress Index and Deformation Activation Energy For aluminum and aluminum alloys, when the value and the applied stress are small, 1 type can be changed by 40% = the differential between the two ends can be obtained. According to the foregoing analysis, it can be seen that the suction 5 alloy is at high temperature. In addition, the U-shaped sinusoidal relationship is added to the U.S. contraction relationship. Therefore, 80 can be used instead of the flow stress in Equation 5 to obtain the Q=R for the deformation activation energy 2, and the stress exponent at different temperatures is different. The experimentally obtained stress index value is 1.

The experimentally obtained relationship between the deformation activation energy 0 and the temperature, strain rate temperature, can be seen from 1 and 4 that the person 1 also has a higher stress index and deformation activation energy. If it is under 500. The deformation activation energy is as high as 7001.1. This is much more than the 142,1 diffusion activation energy of pure niobium. 1 before. The mechanism of this abnormal creep behavior for heat-resistant aluminum gold is not known. The introduction of the concept of critical stress can explain this phenomenon to a certain extent, recently, the creep behavior of the alloy and the bulk-strengthened alloy. This model can also be used to solve the sample 145 gold-plated, 1 temperature creep chamber for the high temperature deformation of the alloy. The mutual attraction between dislocations and dispersed particles 12 is controlled by the final separation process. In order to control the creep rate of the village material. This interaction is caused by the diffusion relaxation of the dislocation stress field at the dispersed particles and at the body interface. The introduction of the relaxation factor, an important physical parameter, can solve the anomalous creep chamber of the 145 alloy from 7 to 4 as well. Below 500. Deformation activation energy increases with increasing temperature. This may be because at 500, the effect of diffusion strengthening was significantly reduced. So that 550, when the deformation activation energy is lower than 500 when the strain rate decreases. Deformation activation energy increases. This may be due to the lower strain rate. Lead to deformation, the longer the room. Which is conducive to triggering analysis; 1 precipitation phase 1210 is also enhanced dispersion reinforcement. As a result, the deformation-induced activation energy increases.

Evaluating the stress exponent and deformation activation energy of the alloy is very useful, and the greater the effect of temperature on the flow stress. The use of deformation shock can help evaluate the high temperature plastic deformation mechanism of the alloy.

25 Relation between alloy deformation resistance and temperature The alloy deformation resistance refers to the ability of the alloy to maintain its original shape and resist deformation under the deformation temperature and deformation degree at a given deformation temperature. For human 1 + brother alloy. The compressive deformation has no obvious yield, and the peak stress can be approximated as the deformation resistance. As mentioned before. Temperature is an extremely important factor that affects deformation resistance. 5 is the relationship between deformation resistance and temperature under conditional strain rate of 2.7710, from which it can be clearly seen that the effect of temperature on the deformation resistance of the alloy deformation resistance, with the increase of temperature decreases, but in 450500, falling within the segment More gentle. After several experiments, it was found that in 450,500 areas, there was indeed a region with less deformation resistance change. When the alloy extrusion is thrown. If the extrusion temperature is lower than 450, due to the large deformation resistance of the alloy, it is difficult to process using the existing conventional equipment; if the extrusion temperature is higher than 500, the grains are significantly coarsened. This severely reduces the mechanical properties of the extruded product. Therefore, considering the above factors, it can be considered that the extrusion temperature is set at about 480, so as to ensure that the material has a low deformation resistance and is easily dry-processed. Can also make the product has a more excellent organizational performance.

3 Conclusion The grain still keeps a fine state. With the rise of the temperature of the vice 1 dispersion strong alloy high-temperature quake deformation invented when the rheology softening. Changes in the activation of chemical warfare can change the role of the person than the tension; For alloys, the effect of the stress level as a function of the activation energy of temperature is much greater. As a result, the deformation activation energy increases and decreases. Increasing the rate of change increases, indicating that the material is a positive strain rate sensitive material.

The experimental alloy has a higher stress index and larger deformation activation energy. At 500, the deformation activation energy increases with temperature, and at 550, the deformation activation energy decreases.

This analysis of high temperature compression thermal simulation results shows that the extrusion temperature of the alloy is set at 480 or so.

Reference Wen Hao 5 Shen Jian. Research on Plastic Deformation Behavior of 2091 Al-Li Alloy. Department of Materials Science and Engineering, Central South University of Technology, 1996.

Peng Liangming, Zhu Shijie, Chen Haoran, et al. 8.5,1.3,1.78 alloy compression and deformation behavior 4. Material Engineering, 199842527.