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研究了铍从室温(25℃)~800℃温度范围的准静态拉伸/压缩力学性能。结果表明,室温下退火态铍的拉伸强度高于未退火的铍,且屈服强度和抗拉强度之间的差距很小。在200~400℃之间铍的塑性随试验温度的升高而增大,并在400℃附近达到最大值,继续升温铍的塑性开始下降。高于600℃拉伸时,铍的应力-应变曲线表现出一定的流变特征,其拉伸强度和加工硬化行为随温度的升高逐渐降低。铍在压缩时会产生明显的塑性变形,该结果表明铍的室温拉伸与压缩性能具有明显的不对称性。回收试样的扫描电镜(SEM)分析结果表明,室温下铍的拉伸断口呈穿晶解理断裂,400℃附近为微孔聚集型断裂,同时铍的晶粒被明显拉长,高于400℃后出现晶间断裂。铍试样轴向剖面的金相(OM)照片表明,拉伸试样在400℃晶粒被明显拉长,而在室温和700℃晶粒形状无明显变化。铍室温压缩面的晶粒与压缩前相比明显变长,室温压缩前后X射线衍射(XRD)分析结果表明,压缩变形后铍的组织与压缩前相比产生了明显的择优取向。
The quasi-static tensile / compressive mechanical properties of beryllium from room temperature (25 ℃) to 800 ℃ were investigated. The results show that the tensile strength of beryllium annealed at room temperature is higher than that of unannealed beryllium, and the difference between yield strength and tensile strength is small. The plasticity of beryllium increases with the increase of the test temperature from 200 ℃ to 400 ℃, and reaches the maximum near 400 ℃. The plasticity of beryllium continues to decrease. When tensile stress is higher than 600 ℃, the stress-strain curve of beryllium shows some rheological characteristics, and its tensile strength and work-hardening behavior decrease with increasing temperature. Beryllium in compression will have a significant plastic deformation, the results show that beryllium room temperature tensile and compressive properties have obvious asymmetry. Scanning electron microscopy (SEM) analysis of recovered samples showed that tensile fracture of beryllium was transgranular cleavage fracture at room temperature, micropore aggregation was observed near 400 ℃, and the grain of beryllium was obviously elongated and higher than 400 ℃ after the intergranular fracture. Metallographic (OM) photographs of the axial section of the beryllium sample show that the tensile specimens were significantly elongated at 400 ° C, while the grain shape did not change significantly at room temperature and 700 ° C. Comparing with pre-compression, the grains at room temperature compression of beryllium obviously lengthened. The results of X-ray diffraction (XRD) before and after compression show that the beryllium structure has obvious preferential orientation compared with that before compression.