Isothermal Bainite in AF1410

The isothermal bainite transformation was identified in AF1410 by the use of thermomagnetic analysis methods. The formation of isothermal bainite in AF1410 has not been previously reported. Mechanical property test results indicate that isothermally processed AF1410 containing a mixture of bainite and martensite exceeds toughness properties of conventionally processed material containing 100% martensite. Moreover, the yield strength of isothermally processed material is the same as conventionally processed material. Because the isothermal transformation to bainite occurs gradually over time, large internal strains are avoided. This contrasts with a thermal martensite transformations where the rapid martensite transformation upon quenching often leads to distortion and cracking. The isothermal bainite in AF1410 can be exploited through the use of current isothermal processing methods to facilitate fabrication of the alloy. Isothermal processing of AF1410 components may permit most of the machining operations to be completed in the annealed condition (Rc 36) rather than in the peak aged condition (Rc 48).