Development of High Strength Metallic Materials Controlled for Nanostructure Using Severe Plastic Deformation

(1)In摘要建立了一套高压扭转实验装置，以实现金属材料在高压下的剧烈塑性变形。该设备允许在高温下使用圆盘型和圆柱型试样。（2）对Al-3%Mg-0.2%Sc合金进行了HPT。旋转和施加的压力对硬度和显微组织的影响进行了研究，这两种类型的标本。硬度随着旋转和施加压力的增加而增加，但两种类型的试样都存在饱和。在试样的外边缘处，晶粒尺寸减小至0.15 μm。在高温下的拉伸试验表明，超塑性伸长率，为500%的圆盘试样和1600%的圆柱试样。（3）150℃热变形后，晶粒尺寸由22 μm减小到0.22 μm，在200℃、应变速率为3.3 × 10 ~（-3）s ~（-1）时，超塑性延伸率达620%<-3><-1>。(4)A通过HPT处理的碳钢在圆盘试样的外边缘处显示出硬度的显著增加。这种趋势与铝合金和镁合金不同。从HPT试样获得1.2GPa的拉伸强度。（5）采用等通道转角挤压（ECA）对可硬化铝合金进行了SPD变形。ECAP处理后的合金在100℃时效后，硬度和均匀延伸率均有所提高。SPD试样在较低温度下进行时效处理，其强度和塑性都有很大的提高潜力。

(1)In this study, a facility for high pressure torsion (HPT) was established in order to impose severe plastic deformation (SPD) on metallic materials under high pressure. This facility permits use of disk-type and cylindrical type of specimens at elevated temperatures for the former type of specimens.(2)HPT was conducted on an Al-3%Mg-0.2%Sc alloy. The effect of rotation and imposed pressure on the hardness and microstructure was examined for both types of specimens. The hardness increased with an increase in rotation and applied pressure but there was a saturation of both types of specimens. The grain size was reduced to 0.15 μm at the outer edges of the specimens. Tensile tests at high temperatures revealed superplastic elongation, of 〜500% for the disk specimens and 〜1600% for the cylindrical specimens.(3)HPT at 150℃ for Mg alloys showed that the grain size was reduced from 22 μm to 0.22 μm which then resulted in a superplastic elongation of 〜620% at 200℃ with a strain rate of 3.3x10^<-3> s^<-1>.(4)A carbon steel processed by HPT exhibited an significant increase in hardness at outer edges of the disk specimens. This trend was different from Al alloys and Mg alloys. Tensile strength of 1.2 GPa was attained from the HPT specimens.(5)Age-hardenable Al alloys were subjected to SPD through equal-channel angular pressing (ECA). Aging at 100℃ for the ECAP processed alloys led to an increase in hardness and also an increase in uniform elongation There was a great potential for an increase in both strength and ductility when SPD specimens are subjected to aging treatment at lower temperatures.