1.1 Metals and Nonmetals金属和非金属Perhaps the most common classifidation that is encountered in materials selection is whether the material is metallic or nonmetallic. The common metallic are such metals as iron, coppor, aluminum, magnesium, nickel, titanium and the alloys of these metals, such as steel brass and bronze. They possess the metallic properties of luster, thermal conductivity and electrical conductivity; they are relatively, ductile and some of them have good magnetc properties. The common nonmetals are wood, brick, concrete, glass, rubber and plastics. Their properties vary widely, but they generally tend to be less ductile, weaker and less derise than the metals, and they have no electrical conductivity and poor thermal conductivity.翻译：也许在材料选择中遇到的最常见的分类是材料是金属的还是非金属的。
常见的金属有铁、铜、铝、镁等金属。
铯、镍、钛和这些金属的合金，如钢、黄铜和青铜。
它们具有光泽、热导率和导电性的金属性质，是一种新型的金属材料。
延展性和部分延展性具有良好的磁性能。
常见的非金属有木材、砖块、混凝土、玻璃、橡胶和塑料。
它们的性质差别很大，但一般倾向于l。
Ess具有延展性，比金属更弱，也更少，没有导电性能，导热性能较差。
1. Metals and Nonmetals金属和非金属Ferrous Metals 黑色金属Nonferrous Metals and Alloys 有色金属和含金2.Metals consisting of iron combined with some other elements are knows as ferrous metals;all the other metals are called nonferrous metals.The most important nonferrous metals are copper(Cu),aluminum(Al),lead(Pb),zinc(Zn),tin(Sn). 由铁和其他元素结合而成的金属被称为黑色金属，所有其他金属都称为有色金属，最重要的有色金属是铜、铝、铅、锌、锡。
3.Mechanical properties are the characteristic responses of a material to applied forces.These properties fall into five broad categories:strength,hardness,elasticity,ductility(plasticity) and toughness.力学性能是材料对施加力的特性响应，这些性质分为五大类：强度、硬度、弹性、塑性和韧性。
Strength is the ability of a material to resist applied forces.强度是材料抵抗作用力的能力。
Hardness is the ability of a material to resist penetration and abrasion.硬度是一种材料的抗渗和耐磨能力。
Elasticity is the ability to spring back to original shape.弹性是指能够弹回原来的形状。
Ductility(plasticity)is the ability to undergo permanent changes(plastic deformation) of shape without rupturing.延展性（可塑性）是发生永久性变化的能力（塑性变形）而不破坏的形状。
Toughness is the ability to absorb mechanically applied energy. 韧性是吸收机械能的能力。
4.Heat treatment is a method used to alter the physical,and sometimes chemical,properties of a materials.热处理是用来改变材料的物理性质，有时甚至是化学性质的方法5.727℃steel is in a solid state with a structure called austenite,or gamma iron,a single phase fee solid solution.翻译：727温钢处于固态状态，奥氏体结构，或γ铁，单相固溶体。
At temperatures below 910℃,pure iron changes to a stable phase called alpha ferrite,alpha iron,or ferrite.翻译：在910度以下的温度下，纯铁变为α铁素体、α铁或铁素体的稳定相。
6.When steel with the eutectoid composition forms at 727℃,it produces a lamellar two-phase mixture of ferrite and cementite called pearlite.翻译：当钢的共析成分的形式在727℃，它产生的片状铁素体和渗碳体两相混合物，称为珠光体7.austenite奥氏体ferrite铁素体cementite渗碳体pearlite珠光体martensite马氏体Annealing 退火crystal defects晶体缺陷recrystallization 再结晶grain growth晶粒生长，颗粒生长normallizing正火Quenching 淬火tempering 回火8.1）Bulk or massive forming operations.块状或块状成形操作。
2）Sheet forming operations.板材成形操作。
In both types of process,the surfaces of the deforming metal and the tools are in contact,and friction between them may have a major influence on material flow.In bulk forming,the input material is in billet,rod or slab form,and the surface-to-volume ratio in the formed part increases considerably uner the action of largely compressive loading.In sheet forming,on the other hand,a piece of sheet metal is plastically deformed by tensile loads into a three-dimensional shape,often without significant changes in sheet thickness or surface characteristic.翻译：在这两种加工过程中，变形金属的表面与工具都是接触的，它们之间的摩擦可能对材料流动有很大的影响。
在批量成形中，输入的材料在小方坯、棒材或板坯的形状，以及成形件的表面体积比，在很大程度上不受压缩载荷的作用下，都有很大的提高。
另一方面，在金属片的形成过程中，金属片在拉伸载荷作用下塑性变形为三维形状，其厚度和表面特征通常没有明显变化。
9.Cold,warm and hot working冷暖热加工Cold working refers to plastic deformation that (usually,but not-necessarily) is carried out below its recrystallization temperature, usually at the ambient temperature.Cold working can increase the strength of the product by a process called work hardening.Work hardening creates microscopic defects inthe metal,which resists further changes of shape.翻译：冷加工指的是通常在环境温度以下的塑性变形（通常，但不一定）是在再结晶温度以下进行的。
产品的强度通过一种叫做加工硬化的过程。
加工硬化会在金属中产生微观缺陷，从而阻止进一步的形状变化。
Cold working generally results in higher yield strength as aresult of the increased number of dislocations and theHall-Petch effect of the sub-grains,and a decrease inductility.The effects of cold working may be reversed byannealing the material at high temperatures where recoveryand recrystallization reduce the dislocation density.翻译：冷加工通常导致更高的屈服强度由于位错和亚晶粒的Hall Petch效应的数量增加，和延展性下降，冷的影响。