EFFECT OF AUSTENITIZING TEMPERATURE ON STRUCTURE AND MECHANICAL PROPERTIES OF 23NiCo ALLOY

摘要

Effectof the austenitizing temperature on the microstructure, strength, and toughness of23 NiCo alloy wasstudied . With increasing theaustenitizingtemperature,the reductionsin strength and hardness are probably caused by the coarsening of M2 Ccarbides. The use of higheraustenitizingtemperatureresultedinimproved impacttoughness duetothe dissolutionof undissolved,( CrFeMo)23 C6 carbides. For austenitizingtemperaturesgreaterthan 950 ℃ resultedinthelossofimpacttoughness. Astheaustenitizingtemperatureisincreasedto1050 ℃impacttoughnesslevelsarereduced on an averageby53 J/cm2 .Examination ofthefrac turesurfaceofimpacttoughnessspecimens viascanningelectron microscopy ( SEM) revealedthataustenitizing at1050 ℃and aged at482℃wasintergranularfracture .It wassuggested thatthisgrain boundary embrittlement wastheresultofthe formation of cementite particlesduring aging.