Sulphur distribution in K24 cast nickel-base superalloy and its influence on mechanical properties

Abstract

The distribution of sulphur (S) in K24 cast nickel-base superalloy and its influence on the tensile and stress-rupture properties have been studied. The S content varied between 0.OO2-D.12 weight %. S exists in the Yphase - a sulphocarbide of approximate chemical composition M₂SC where MC is usually Ti with a small amount of Nb, V and Mo, the amounts of Sand C being about 10-20 and 3-18 weight %, respectively - and the metal carbide (MC) phase. S segregates in the grain boundaries and interdendritic region. The amount of S in the central region of MC is higher. Some S is precipitated in the M₂₃C₆ phase during ageing. The volume % of the Y phase is directly proportional to the S content of the alloy. S degrades the tensile and stress-rupture properties of the alloy.

Keywords:

• Stress-Rupture Properties
• Tensile Properties
• Sulphur
• Nickel-Base Superalloy