42CrMo alloy steel plate forgings require tempering treatment after forging. Because of the great difference of cross-section size, the tendency of water quenching cracking is large, the quenching hardness of large cross-section of 42CrMo alloy steel plate after oil quenching is low, and the failure of metallographic structure and mechanical properties often occurs, which directly affects the fatigue strength of crankshaft and the service life of 42CrMo alloy steel plate.
42CrMo alloy steel plate has high strength and high yield point, and its comprehensive mechanical properties are better than 40Cr alloy steel plate. The cold deformation plasticity and machinability of 42CrMo alloy steel plate are medium, and the superheat sensitivity is small, but it has temper brittleness tendency and white spot sensitivity, which are generally used under the condition of quenching and tempering.
42CrMo alloy steel plate is quenched with water-soluble quenching medium. In order to ensure the normal use of quenchant, the temperature of quenchant must be strictly controlled. The reverse melting point of quenching medium is 70℃, and the optimum temperature is (30-60)℃. The quenching liquid temperature of 42CrMo alloy steel plate must always be controlled within the range of process requirements.
