Study on the Weldability of Ni Base Superalloy (Part 5)

Inquiring into Causes of Weld Crakcings in Inconel 713

Abstract

In this report, the presumption of crack initiation temperature was attempted first.
The hot ductility behaviors during cooling process of weld thermal cycle in hot crack sensitive Inconel 713C and insensitive Inconel 713C were investigated.
The causes of hot crackings in Inconel 713C were clarified in conformity to the experimental results with crack initiation temperature and hot ductility behaviors, and general consideration with the relation between hot crack sensitivity and hot ductility behavior during cooling process of weld thermal cycle or local melting phenomenon in an alloy.
The conclusions obtained in this study are as follows;
1) It is presumed that weld crackings in the heat affected zone of Inconel 713C initiates at the temperature more than 1200°C at least.
2) Nil-ductility temperature ranges of the alloy containing white constituents (Heat V-3) and the alloys containing no white constituents (Heat V-11, V-32, V-34) are about 100°C and 10-30°C respectively. The extensive nil-ductility temperature range of Heat V-3 is due to low melting point white constituents.
3) Hot crack sensitive Inconel 713C contains white constituents and its nil-cuctility temperature range is wide.
The main cause of hot crackings in the heat affected zone of Inconel 713C is white constituents considering the fact that low melting point white constituents is the dominant cause to spread nil-ductility temperature range.