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为了研究锻造和轧制这两种开坯工艺对纯钛板坯组织和性能的影响,在Gleeble-1500热模拟实验机上进行热压缩实验,通过单向拉伸实验测试锻造和轧制后板料的力学性能,在光学显微镜下观察采用两种开坯工艺加工后的显微组织。以变形温度(T)和应变速率的对数(lg)为坐标作图,根据lgZ值的斜率,即15.4和17.5,能够将纯钛塑性变形分成3个区,即三阶段加工硬化区、二阶段加工硬化区和流动软化区。在较高Z值的两种加工硬化区会有变形孪晶出现。两种开坯生产工艺对纯钛板坯组织和性能的影响主要体现在:锻坯微观组织出现变形孪晶,即晶内出现交叉孪晶,还有一些孪晶横穿晶界。然而,在轧坯中没有发现孪晶,其微观结构主要为等轴晶和板条状晶粒。拉伸实验和显微硬度测试结果显示,锻坯的屈服和抗拉强度及显微硬度均高于轧坯的。
In order to study the effect of forging and rolling on the microstructure and properties of pure titanium slabs, hot compression tests were performed on a Gleeble-1500 thermal simulation machine and the forging and rolled sheets were tested by a uniaxial tensile test The mechanical properties of the optical microscope were observed using two kinds of billet processing microstructure. According to the logarithm of the deformation temperature (T) and strain rate (lg), the plastic deformation of pure titanium can be divided into three zones according to the slopes of lgZ values of 15.4 and 17.5, that is, the three-stage work hardening zone, Stage of work hardening and flow softening zone. Deformation twins appear in both work-hardened zones with higher Z values. The effect of two kinds of billets on the microstructure and properties of pure titanium slabs is mainly manifested in that the deformation twins appear in the microstructure of the forged billets, that is, there are twins in the crystal and some twins cross the grain boundaries. However, no twins were found in the billets and the microstructures were predominantly equiaxed and lath-shaped grains. Tensile test and microhardness test results show that the forging yield and tensile strength and microhardness are higher than the blank.