Three failure forms of casting molds There are many types of casting molds, and the failure forms are summarized in three ways: wear, fracture, plastic deformation. These three forms of failure.

    First, the wear failure, the mold at work, and the forming blank contact, resulting in relative movement due to the relative movement of the surface, the contact surface gradually lost material phenomenon is called wear.

    Wear failure can be divided into the following:
    a, fatigue wear, the two contact surface relative movement, the cyclic stress (mechanical stress and thermal stress) under the action of the surface metal fatigue off the phenomenon known as fatigue wear.

    b, cavitation wear and erosion wear, the metal surface of the bubble burst, resulting in instantaneous impact and high temperature, so that the mold surface to form a small pitting and pits phenomenon called cavitation wear; liquid and solid particles repeated high-speed impact mold surface , So that the mold surface of the local material loss, the formation of pitting and pits phenomenon called erosion wear.

    c, abrasion wear, in the friction process, the mold surface and the surrounding medium chemical or electrochemical reaction, coupled with the mechanical role of friction, causing the phenomenon of surface material loss is abrasive wear; in the mold and the workpiece (or blank) relative Movement, wear is often in a variety of forms coexist, and mutual influence.

    Second, the fracture failure: casting molds appear large cracks or separated into two parts and part of the loss of working ability, become a fracture failure; fracture can be divided into plastic fracture and brittle fracture. Mold materials are mostly medium and high strength steel, broken form mostly brittle fracture, brittle fracture can be divided into one-time fracture and fatigue fracture.

　　Third, the plastic deformation failure: the mold in the work to bear a lot of stress, and uneven, when a part of the mold stress exceeds the temperature at the time of the mold material yield limit, it will lattice slip, twins , Grain boundary slip, etc. to produce plastic deformation, change the geometry or size, and can not repair and then work, called plastic deformation failure, plastic deformation of the failure of the performance of the form of upsetting, bending, cavity swelling, collapse and so on.