Tensile properties and fracture mechanism of IN-100 superalloy in high temperature range

Milan T Jovanović,Đorđe Drobnjak,Vesna Maksimović,Ivana Cvijović‐Alagić

doi:10.30544/239

Milan T Jovanović, Đorđe Drobnjak + Show 2 more

Open Access

https://doi.org/10.30544/239

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Abstract

Tensile properties and fracture mechanism of a polycrystalline IN-100 superalloy have been investigated in the range from room temperature to 900°C. Optical microscopy (OM) and transmission electron microscopy (TEM) applying replica technique were used for microstructural investigation, whereas scanning electron microscopy (SEM) was utilized for fracture study. High temperature tensile tests were carried out in vacuumed chamber. Results show that strength increases up to 700°C, and then sharply decreases with further increase in temperature. Elongation increases very slowly (6-7.5%) till 500°C, then decreases to 4.5% at 900°C. Change in elongation may be ascribed to a change of fracture mechanism. Appearance of a great number of microvoids prevails up to 500°C resulting in a slow increase of elongation, whereas above this temperature elongation decrease is correlated with intergranular crystallographic fracture and fracture of carbides.

Highlights

Nickel-base superalloys, cast and wrought, derive their strength from the mechanism of solid-solution hardening and precipitation hardening, singly or in combination
It should be noted that the turbine blades fabricated from IN-100 by investment casting were installed in combustion chamber of Rolls Royce jet engines “RR Viper 11“(„G-4 Galeb-4“) and „RR Viper 632“(„G-4 Super Galeb“) in as cast condition, i.e. without any previous heat treatment
Strength increases with temperature up to 700 °C and suddenly decreases

Summary

Introduction

Nickel-base superalloys, cast and wrought, derive their strength from the mechanism of solid-solution hardening and precipitation hardening, singly or in combination. The predominantly solid-solution alloys, such as IN-100, contain significant amount of Al, Ti or Nb, added to promote formation of the dispersed second phase – notably ’. IN-100 belongs to a group of cast non-heat treatable superalloys. The amount of the strengthening phase ’ formed after cooling may be 60% at the maximum and cannot be increased by the following heat treatment. That is why the amount of Ti and Al in IN-100 is twice higher than in other cast, but heat treatable superalloys (see Table 2 in [7]). It should be noted that the turbine blades fabricated from IN-100 by investment casting were installed in combustion chamber of Rolls Royce jet engines “RR Viper 11“(„G-4 Galeb-4“) and „RR Viper 632“(„G-4 Super Galeb“) in as cast condition, i.e. without any previous heat treatment

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