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1.
Commercial purity aluminum (99.5%) was fabricated by equal channel angular pressing (ECAP) up to total accumulated strains of approx. 10. The annealing behavior of material deformed to total strains of approx. 1 and 10 was investigated, using heat treatments of 2 h at various temperatures from 100 to 500 °C. The microstructure of the annealed materials was characterized using the electron back-scatter pattern technique. A number of parameters were determined including the distribution and average values of both the boundary spacings and misorientations. For samples deformed to a total strain of 1, annealing resulted in discontinuous recrystallization. For samples deformed to a total strain of 10, annealing resulted in microstructures exhibiting characteristics of both uniform coarsening and, in a number of places, of discontinuous recrystallization. An attempt was made, based on the boundary spacing distributions, to separate these two components. The grain size after annealing was still however small, being just 6.4 μm after 2 h at 300 °C. 相似文献
2.
Total simulation model of the thermo-mechanical process in shape rolling of steel rods 总被引:2,自引:0,他引:2
The production of steel reinforcing bars for civil engineering is investigated by means of FEM-simulation. An integrated system for computing appropriate thermo-mechanical parameters of the rolling process is proposed. Generalized plane strain approach and coupled thermal-mechanical solution are applied. The microstructural model combines both the effect of the recrystallization mechanisms (static, dynamic and metadynamic) upon the austenite grain forming in hot rolling and that of phase transformation upon the final microstructure. The phases are created during interrupted below the temperature of martensite transition cooling. Thus a typical industrial process for thermo-mechanical strengthening of reinforcing bars, known as Tempcor-process is considered. Computational results are validated to experimental measured mechanical properties of the steel. By means of computer simulation the system can perform different solutions, giving the possibility to obtain a reasonable choice of different thermo-mechanical rolling conditions. 相似文献
3.
Phenylbutazone was recrystallized from its solutions by using a supercritical fluid antisolvent process. It was dissolved
in acetone and supercritical carbon dioxide was injected into the solution, thereby inducing supersaturation and particle
formation. Variation in the physical properties of the recrystallized phenylbutazone was investigated as a function of the
crystallizing temperature and the carbon dioxide injection rate. The recrystallized particles showed cleaner surfaces and
more ordered morphology compared to the particles obtained by other methods such as solvent evaporation. X-ray diffraction
patterns indicated that the crystallinity of the particles had been modified upon the recrystallization. Differential scanning
calorimetry measurement revealed that the crystallizing temperature influenced the thermal stability of the resulting crystals.
Larger crystals were produced when the carbon dioxide injection rate was reduced. 相似文献
4.
Microstructure evolution during metal forming processes 总被引:8,自引:0,他引:8
Recrystallization and grain growth evolutions during metal forming processes are considered. Coupling between the thermo-mechanical and microstructure processes is realized. Die forging of a rear-axle flange is simulated numerically on the base of the finite element method. Material parameters of the models are obtained experimentally. The influence of interpass and holding times on grain size distributions in the end product is shown. 相似文献
5.
本文介绍了用一种再结晶技术制造高炖、超细Al_2O_3粉体的新方法。 将硫酸铝铵溶液(AA)滴入碳酸氢铵溶液(AHC),经过反应合成一种新的含铝化合物,碳酸氢铝铵(AACH),然后在高温下煅烧,生成超细Al_2O_3粉体。另外还采用了X射线,红外光谱,DTA,以及TEM等手段,研究了反应温度、浓度、PH值和老化条件等对生成物AACH和Al_2O_3的影响。 相似文献
6.
7.
富银的Ag—Au合金再结晶 总被引:1,自引:0,他引:1
用示差扫描量热(DSC)硬度测量等方法研究了无限互溶系统的Ag-Au合金在Au含量小于5wt.%,溶质Au及不同变形量对该合金再结晶温度Tr的影响,并与有限固溶系统Ag-Cu合金进行了比较,结果表明:Au对基体Ag的再结晶有一定障碍作用,但与Cu相比,这种作用小得多,变形量越大,Ag-Au合金的再结晶温度越低,讨论了Ag-Au合金的再结晶表现激活能,激活能随Au含量的变化与Au含量对再结晶温度的影 相似文献
8.
热处理对Mg-Y-Mn-Sc合金显微组织演变的影响 总被引:2,自引:0,他引:2
采用光学显微镜、扫描电子显微镜和X射线衍射分析等研究了MgY5Mn1Sc0.3镁合金的显微组织特征及热处理条件下的组织结构演变行为。结果表明:铸态组织由粗大的晶粒构成,晶内出现大量“辫子”状孪晶和呈线状排列的颗粒相,晶内和晶界上没有观察到枝晶和共晶组织,Y元素出现严重偏聚,主要富集在颗粒相中。在固溶处理条件下,组织结构演变和再结晶同时发生,伴随发生组织“球化”、分散相的溶解和聚集以及晶粒由大变小再由小变大。通过维氏硬度HV10的测定,探讨了试验合金的热处理行为。 相似文献
9.
H.F.G. de Abreu A.D.S. Bruno S.S.M Tavares R.P. Santos S.S. Carvalho 《Materials Characterization》2006,57(4-5):342-347
AISI 444 is a Mo-alloyed ferritic stainless steel which presents good naphthenic corrosion resistance, making it attractive for applications in petroleum refining plants; however, good formability is also important. To achieve good formability with this alloy the annealing process is crucial. The annealing temperature in ferritic stainless steel is usually around 850 °C, which falls in the range of sigma phase precipitation. A means to avoid this precipitation is to anneal at temperatures around 1000 °C followed by rapid cooling. Annealing at high temperatures can cause grain growth and carbide or nitride precipitation which can result in a reduction of room temperature toughness. In this paper, the rolling and recrystallization textures of AISI 444 steel were studied in samples cold rolled with different thickness reductions (30%, 60%, 80% and 90%) followed by annealing at 955, 980 and 1010 °C. Aspects of grain size and carbide precipitation after annealing were characterized using EBSD and AFM. The material drawability was analyzed through strain rate or Lankford (r) coefficients calculated from texture results. 相似文献
10.