Abstract

In this work, results of an investigation of the microstructure evolution in Haynes® 230® alloy are presented. The morphological and chemical compositions of the chosen microstructure’s constituents, such as the primary and secondary carbides, were analyzed based on tests in the temperature range 700–800 °C for 1000–3000 h. The prediction of phase evolution within the microstructure was proposed based on the analysis of mutual replacement of carbide-forming elements at the carbide/matrix interface. Based on the results, some complementary markers were considered to describe Haynes® 230® microstructure evolution. Qualitative markers, i.e., defined morphological features, were related to the shape and distribution of microstructure constituents. The study also used quantitative markers related to the local chemical compositions of carbide particles, determined as the ratio of the concentrations of carbide-forming elements Crc/Wc, Crc/CrM and Wc/WM. Microstructure maps created on the basis of these complementary markers for the successive annealing stages reflected the course of its morphological evolution.

Highlights

  • Structural components made of nickel-based heat-resistant alloys such as Haynes® 230® are subjected to the effects of high temperature and load simultaneously during exploitation

  • Microstructure of the examined alloy, Haynes® 230®, was revealed on the microscope images consisting of grains of solid solution γ(Ni)+γ’ and particles of the second phase, i.e., carbides, which were inside grains and in the form of the network on grain boundaries (Figures 2–7)

  • Seven morphological patterns were revealed, in classes predefined in a natural language: compact/monophase, compact/two-phase (M), eutectic (E), filigree (F), dispersed particle in matrix (DM), dispersed particles on grain boundary (DG), and plate (P) (Table 3)

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Summary

Introduction

Structural components made of nickel-based heat-resistant alloys such as Haynes® 230® are subjected to the effects of high temperature and load simultaneously during exploitation. In order to avoid the influence of the size of the excitation zone in the X-ray point microanalysis, an adequate coefficient will be searched for, such as the ratio of the local concentration of carbide-forming elements. In this way, based on a set of visual and chemical features of carbides which result from the annealing time and temperature, it will be possible to develop maps for a specific state of the alloy microstructure

Material for Examinations
II III IV V VI
Microstructure Characterization
Plate P
Conclusions
Full Text
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