The feed die is an important part of the feed press machine. During the work, it is subjected to impact load, abrasive wear and fatigue stress, the die is subjected to complex forces, and the working environment is harsh. The technical requirements stipulate that the pressing die should have high strength and high wear resistance, high impact toughness and excellent fatigue resistance. During the production, it was found that excessive wear and surface peeling of the workpiece occurred in the die pressing feed, resulting in the failure of the workpiece and a low service life. Therefore, heat treatment by ultrasonic induction hardening equipment is required to improve its toughness, friction and compression resistance.
According to the analysis, in order to obtain the bainite matrix of ductile iron, the quenching medium is required to have a slower cooling rate. The water glass aqueous solution supersonic frequency quenching equipment forms a steam film on the surface of the workpiece during quenching, and the cooling speed of the workpiece is relatively slow. After entering the convection stage, the workpiece is covered with a layer of water glass on the surface, and its cooling speed is also slow. The water glass aqueous solution used The quenching effect is crystal good. When the quenching and austenitizing temperature is 890-910°C, better strength, hardness and impact toughness coordination properties are obtained. From 860-900℃, the hardness and impact toughness of the workpiece increase with the increase of temperature. This is because as the austenitization temperature increases, the solid solution content of carbon and alloy elements in austenite increases, and the austenite is more stable. Hardenability increases, increasing austenite and martensite. However, if the temperature is too high, exceeding 910-930°C, the impact toughness will decrease. At the same time, if the austenitizing temperature is too high, the quenching stress will be increased and the tendency of quenching cracks will be increased. The austenitization temperature should also consider the influence of the as-cast structure. When there are more carbides in the as-cast structure, the austenitization temperature and time can be appropriately increased to promote the decomposition of carbides and reduce the number of carbides in the quenched structure; When there is a lot of ferrite in the structure, the austenitization temperature and time can be appropriately increased to promote the dissolution of ferrite and the homogenization of austenite, and improve the performance of the workpiece after quenching. The test shows that when the heating temperature rises, E carbides are precipitated in the grains of bainite, so that the supersaturation of bainite decreases, the hardness decreases, the quenching stress decreases, and the impact toughness increases. Select the tempering temperature to be 250-300°C. The heat treatment process of bainite anti-wear ductile iron is preferably supersonic frequency quenching equipment: the austenitization temperature is 880--920°C, the tempering temperature is 250-300°C; the quenching medium is water glass aqueous solution, and the working temperature is F i degrees 30 - 80 ℃; after quenching by supersonic audio quenching equipment, the structure of ductile iron with bainite as the matrix is obtained. The bainite wear-resistant ductile iron die has good comprehensive mechanical properties, the hardness is 50-55HRC, the hardness is uniform, and the impact fatigue resistance is high. The impact fatigue test of the workpiece is 20,000 times, and there is no fatigue shedding and fracture failure.
After the bainite wear-resistant nodular cast iron die adopts the improved super-audio frequency induction hardening equipment quenching process, the workpiece strength, impact toughness and impact fatigue performance are excellent, the service life of the workpiece is improved, there is no excessive wear and fatigue shedding, and the production runs well.
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GS-ZP-1200
