资料力学 论金属的断裂(国外英文资料).docVIP

材料力学 论金属的断裂(国外英文资料) Work in engineering material mechanics Class 2 Named tao shuai School numberDiscuss the fracture of the metal One, basic introduction Concept: the phenomenon of metal material breaking into two parts under external force. Wear, corrosion and fracture are the three main forms of failure of the machine. In the case of stress (and sometimes a combination of heat and medium), the metal material is divided into two or several parts, known as total rupture; Internal cracks are not completely broken. It is proved that the fracture process of most metal materials includes two stages of crack formation and expansion. For different types of rupture, the mechanism and characteristics of these two phases are not the same. The basic type of fracture Elastic deformation, plastic deformation, fracture According to the size of the macroscopic plastic deformation before the fracture of the material, the fracture type is determined, which can be divided into ductile fracture and brittle fracture. When the polycrystalline metal breaks, the path of the crack extension can be divided into the fault of the transgranular and the crystalline fracture. According to the type of stress, it can be divided into pure shear fracture and microporous aggregate fracture and cleavage fracture. Three, specific analysis 1, the toughness fracture Ductile fracture is the metal material before rupture causes obvious macroscopic plastic deformation, fracture, the fracture has torn a slow process, constantly in the process of crack propagation energy consumption. The fracture surface of the ductile fracture is usually parallel to the maximum shear stress and is 45 with the main stress. Angle. When viewed with the naked eye or magnifying glass, the port is fibrous and dark. The fibers are caused by the continuous expansion and interconnection of microfissures in the process of waking and deformation, and the dark color is caused by the weak reflection ability of the fibrous f