P91)机械工业用于制造产品的材料，可以分为金属材料、合成材料、陶瓷和复合材料四大类。2)金属可分为有色金属和黑色金属。3)塑料可分为热固性材料和热塑性材料。1 Engineering materials those go into produces can be divided into metallics,polymers,ceramics and composites。2.Metallics can be divided into ferrous and nonferrous metals.3plastic can be divided into thermosetting plastic or thermoplastic plastic.P171)材料的特性可分为物理特性和化学特性两大类。2)塑性材料在拉伸载荷下应力达到屈服强度时，产生塑性变形。3)除软钢等材料有明显的屈服点外，合金钢和有色金属等塑性材料无明显的屈服点。1。The properties of materials can be divided into physical
