English for Mechanical Engineering,机械工程专业英语,常州工学院机电工程学院 徐红丽,机械工程专业英语,预备知识,一、Background Information,Metal Materials ( 金属材料),There are many different material types to choose from when undertaking a project.In matierial science, the materials are grouped roughly into two categories, these being “Non-metallic“ and Metallic“. In respect to metallic materials these are then subsequently grouped into two groups being ferrous and non-ferrous. Each of the materials has their own characteristics and requires different machining techniques. Careful consideration needs to be given to the correct material selection for its application. (Definition: Ferrous as in containing Iron, e.g steel - Non-ferrous as in not containing Iron e.g aluminium, copper) A simple test for ferrous/non-ferrous materials is to use magnet as a magnet will sick to ferrous materials due to its iron content.,Lesson 5 Metallic and Nonmetallic Materials,机械工程专业英语,预备知识,一、Background Information,Aluminium Alloy,There are many kinds of Alloys to choose from but often, Aluminium is chosen as it is lightweight (about 2700 kg/m3 density), it is comparatively soft and its process-ability is good. From a machining viewpoint pure aluminium greatly differs from Al-Cu alloy。Pure aluminium is easy to bend but it is difficult to process as it is too soft and easily clogs cutting tools. On the other hand, the Al-Cu alloy is easy to handle and cut with several of the grades having strength similar to that of steel. However, one of the drawbacks of aluminium is that it is difficult to weld, solder and bend.,Lesson 5 Metallic and Nonmetallic Materials,机械工程专业英语,预备知识,一、Background Information,Carbon Steel,Typical carbon steel materials are very cheap, excelling in weldability, and they can be subjected to various heat treatments. Since many machine tools are designed to cut mild steel material, it is very rare to encounter problems while machining. Generally, mild steel has a black surface and this surface is very hard, if possible, this surface should be left intact as it offers additional protection.,Lesson 5 Metallic and Nonmetallic Materials,机械工程专业英语,预备知识,一、Background Information,Common Shapes,Material is usually supplied as common shapes and these are (a) Billets (columns), (b) flat bar (boards), (c) Angle (L-shaped), (d) “C“ channel (C-shaped) and (e) pipe. The correct selection of material assists in simplifying a project.,Lesson 5 Metallic and Nonmetallic Materials,机械工程专业英语,预备知识,一、Background Information,Non-metal,Lesson 5 Metallic and Nonmetallic Materials,There is no rigorous definition for the term “nonmetal“ - it covers a general spectrum of behaviour. Common properties considered characteristic of a nonmetal include: poor conductors of heat and electricity when compared to metals they form acidic oxides(whereas metals generally form basic oxides) in solid form, they are dull and brittle, rather than metals which are lustrous, ductile or malleable usually have lower densities than metals they have significantly lower metaling point and boiling points than metals non-metals have high electronegativity,mlibladj. 可锻造的, 有延展性的，韧性的,Lesson 5 Metallic and Nonmetallic Materials,机械工程专业英语,stress 应力 strain 应变 density 密度 strength 强度 hardness 硬度 rigidity 刚度 elasticity弹性 plasticity（ductility） 塑性 toughness 韧性 compression 压缩 tension 拉伸 bend 弯曲 torsion 扭转 shear 剪切 fatigue 疲劳 deformation n. 变形 metal forming process n. 金属成型工艺（过程),词 汇,机械工程专业英语,课文分析,Perhaps the most common classification that is encountered in materials selection is whether the material is metallic or nonmetallic. The common metallic are such metals as iron, copper, aluminum, magnesium, nickel, titanium, lead, tin, and zinc and the alloys of these metals, such as steel, brass, and bronze. They possess the metallic properties of luster, thermal conductivity, and electrical conductivity; are relatively ductile; and some have good magnetic properties. The common nonmetals are wood, brick, concrete, glass, rubber, and plastics. Their properties vary widely, but they generally tend to be less ductile, and less dense than the metals, and they have no electrical conductivity and poor thermal conductivity.,Lesson 5 Metallic and Nonmetallic Materials,机械工程专业英语,课文分析,Perhaps the most common classification that is encountered in materials selection is whether the material is metallic or nonmetallic.,The common metallic materials are such metals as iron, copper, aluminum, magnesium, nickel, titanium, lead, tin, and zinc and the alloys of these metals, such as steel, brass, and bronze.,在材料选择时所遇到的最普通的分类问题，可能就是这种材料是金属材料还是非金属材料。,最常见的金属材料如铁，铜，铝，镁，镍，钛，铅，锡和锌以及这些金属的合金，例如钢，黄铜和青铜。,mni:zjmn. 镁,taiteinimn.钛,Lesson 5 Metallic and Nonmetallic Materials,机械工程专业英语,课文分析,They possess the metallic properties of luster, thermal conductivity, and electrical conductivity; are relatively ductile; and some have good magnetic properties.,