第一章材料结构和性能thefirst课件.ppt

第一章工程材料的结构与性能 The first chapter the engineering material structure and properties;1.强度strength ;一 单向拉伸试验 Uniaxial tensile test;工程材料的性能分为使用性能和工艺性能。 对绝大多数工程材料来说，其力学性能是最重要的使用性能。 ???静载时材料的力学性能 ????静载是指对试样缓慢加载。最常用的静载试验有拉伸、压缩、硬度、弯曲、扭转等，利用这些不同的试验方法，测得各种力学性能指标，如强度、塑性和硬度指标。Engineering material performance is divided into use function and process performance. For the vast majority of engineering materials, its mechanical performance is the most important performance. When the static load the mechanical properties of materials of the sample of the static load is to point to slow loading. The most commonly used the static load test of a stretch, compression, hardness, bending, torsion and so on, the use of these various test method, the various mechanical performance indicators, such as strength, plastic and hardness index.????;强度 ????强度是指在外力作用下，材料抵抗变形和断裂的能力。????强度指标常通过拉伸试验测定。下图为退火低碳钢的拉伸试验载荷（拉力）与变形量（伸长量）的变化图， 可以从曲线上直接读出材料的一些常规力学性能指标。 1. Strength strength is to point to in the external force, the materials resistance to deformation and fracture ability. Strength indexes often through determination of tensile test. This illustration shows the annealing of low carbon steel tensile test load (tension) and deformation (elongation), from variations on the curve of the conventional materials directly read some mechanical performance indicators.;;?屈服强度σs：在上图的拉伸曲线中，在s点出现不可恢复的变形，即塑性变形。 所以s点就是材料在外力作用下开始发生塑性变形的最低应力值，称为屈服极限或屈服强度,用σs表示（单位为MPa），The yield strength sigma σs s: in the image above tensile curves, appear not resume in s point of distortion, namely plastic deformation. So s point is material under external force beginning to happen plastic deformation of the lowest stress value, called yield limit or yield strength, with sigma σs s said (MPa), unit for即???????????????????????????????????????? ?????　　?? 弹性极限σe和弹性模量E：在拉伸曲线上,e点以前产生的变形是可以恢复的变形，叫做弹性变形,e点所对应的弹性变形阶段的最大应力，称为弹性极限，以σe表示（单位为MPa）。 Elastic limit sigma σe and elastic modulus E : in the curve, e o clock deformation