(AerospaceBook)HOT CRACKING OF ALLVAC 718PLUS, ALLOY 718 AND WASPALOY AT VARESTRAINT TESTING

摘要

Varestraint testing together with DSC and SEM-EDX analyses have been performed as meansof investigating the hot cracking susceptibility of Allvac 718Plus, alloy 718 and Waspaloy. Thesolidification sequences in Allvac 718Plus and alloy 718 were very similar to each other starting by aninitial solidification of the gamma phase, gamma/MC reaction at around 1260 C and then finallyending the sequence by gamma/Laves eutectic reaction at around 1150 C. Waspaloy had the samesolidification sequence, except no Laves phase formation takes place, and solidification started at asomewhat higher temperature as compared to alloy 718 and the solidification sequence ends by agamma/MC reaction at around 1245 C. The total amount of hot cracking in Waspaloy was shown to bemuch less than that in alloy 718 and in Allvac 718Plus which is believed to be related to the presenceof the Laves eutectic in the latter two alloys with corresponding larger solidification ranges. Hotcracking of 718Plus is slightly less than in 718.