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A microstructural study of HAZ cracking in conventionally and directionally cast polycrystalline and single crystal IN-738 LC

IN-738 LC, a precipitation hardened nickel based superalloy, containing substantial amounts of Al + Ti contents, is very difficult to weld due to its high susceptibility to HAZ cracking, during welding via conventional fusion welding techniques and subsequent PWHT. The cracking is mainly intergranular in nature and associated with liquation of secondary solidification products (such as MC carbides,  -  eutectic phases), and solid state reaction products ( precipitate particles) that are present along the grain boundaries in the pre-weld material. The current research was to find effective ways to improve weldability of IN-738 LC. Laser welds were produced autogenously on conventionally solidified (CS) and directionally solidified (DS) polycrystalline, and single crystal (SC) IN-738 LC subjected to two preweld heat treatments. Weldability was assessed by measuring the total crack lengths in HAZ. The influence of grain boundaries and heat treatment on extent of cracking in IN-738 LC was studied.

Identiferoai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/24056
Date17 September 2014
CreatorsSanghvi, Jinal Nithin
ContributorsChaturvedi, M.C. (Mechanical Engineering) Ojo, O.A. (Mechanical Engineering), Richards, N.L. (Mechanical Engineering) Shalaby, A. (Civil Engineering)
Source SetsUniversity of Manitoba Canada
Detected LanguageEnglish

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