Continuous Casting of Incoloy800H Superalloy Billet under an Alternating Electromagnetic Field

Fei Wang,Xiujie Xu,Engang Wang,Anyuan Deng,Lintao Zhang

doi:10.3390/met6010002

Abstract

We experimentally investigate the influence of an alternating electromagnetic field on the surface and internal qualities of Incoloy800H superalloy billets. The electromagnetic continuous casting experiments for Incoloy800H superalloy were successfully conducted and the billets (0.1 m × 0.1 m × 1.2 m) were obtained. We figure out that the high frequency (20.4 kHz) electromagnetic field which is applied in the mould region can improve the surface quality of Incoloy800H superalloy billet remarkably; the depth of oscillation mark decreases from 1.2 mm (without electromagnetic field) to 0.3 mm (with electromagnetic field). The internal quality of the billet was studied using a variety of characterization techniques. The low frequency (5 Hz) electromagnetic field which is applied in the second cooling region can improve the internal quality; the region of the equiaxed grain increases from 2.45% (without electromagnetic field) to 41.45% (with electromagnetic field). Furthermore, macro- and micro-segregation are suppressed and the TiN inclusion number is decreased as well.

Highlights

Incoloy800H superalloy (UNS N08810) is an austenitic Fe-Ni-Cr superalloy with excellent strength and resistance to oxidation and carburization, under high-temperature conditions
The alloy is widely used in equipment that experiences long-term exposure to high temperatures and corrosive atmosphere, e.g., pigtails, radiant tubes and intermediate heat exchangers (IHX)
The results showed that the oxidation kinetics of three different zones followed the parabolic-rate law in dry and wet air

Summary

Introduction

Incoloy800H superalloy (UNS N08810) is an austenitic Fe-Ni-Cr superalloy with excellent strength and resistance to oxidation and carburization, under high-temperature conditions. The corrosion behavior of Incoloy800H superalloy in supercritical water (374 ̋ C, 22.1 MPa) was investigated [1] and the results showed that an oxidation process was observed as the primary corrosion behavior. Further research on this oxidation behavior, along with its mechanisms, in the vicinity of three different zones (containing the substrate, heat-effected zone and the melt zone) in dry and wet air conditions was conducted [2]. The results showed that the oxidation kinetics of three different zones followed the parabolic-rate law in dry and wet air. The neutron diffraction method was used to determine the residual stresses [4], e.g., for an 8 mm Incoloy800H weld

Methods

Results

Conclusion