INFLUENCE OF MICROSTRUCTURE AND MECHANICAL PROPERTY OF 42MnMo7 STEEL FOR DIFFERENT CONDITION

Under the hot rolling condition,the microstructures of tubing and coupling stock 42MnMo7 steel are course upper bainite,widmanstaten and pearlite,which made the material have high strength and lower toughness. The bad structure of 42MnMo7 steel is determined by its chemical composition. Martensite start points (MS) is lower,which will cause bainite transition or martensite transition with air cooling. The normalizing or tempering or combination heattreatment have a small effect for the bad structure. Good toughness will be got if take quench and temper,but the cost is higher.