Electron microscopy study of carbides precipitated during destabilization and tempering heat treatments of 25 wt.%Cr-0.7 wt.%Mo high chromium cast irons

Amporn Wiengmoon; John T H Pearce; Sankum Nusen; Torranin Chairuangsri

doi:10.1016/j.micron.2021.103025

Electron microscopy study of carbides precipitated during destabilization and tempering heat treatments of 25 wt.%Cr-0.7 wt.%Mo high chromium cast irons

Micron. 2021 Apr:143:103025. doi: 10.1016/j.micron.2021.103025. Epub 2021 Jan 27.

Authors

Amporn Wiengmoon¹, John T H Pearce², Sankum Nusen³, Torranin Chairuangsri³

Affiliations

¹ Department of Physics, Faculty of Science, Naresuan University, Phitsanulok, 65000, Thailand. Electronic address: ampornw@nu.ac.th.
² Panyapiwat Institute of Management, Nonthaburi, 11120, Thailand.
³ Department of Industrial Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand.

PMID: 33549852
DOI: 10.1016/j.micron.2021.103025

Abstract

The effect of a 0.7 wt.%Mo addition on the microstructure and hardness of a heat treated 25 wt.%Cr-2.4 wt.%C cast iron has been studied via comparison with a Mo free reference 25 wt.%Cr-2.4 wt.%C iron. Destabilization led to precipitation of M₇C₃ and M₂₃C₆ secondary carbides in the reference iron, whereas M₂₃C₆ secondary carbide was found in the iron with 0.7 wt.%Mo. Tempering resulted in additional secondary carbide precipitation and formation of ferrite. Secondary hardening was found in the iron with 0.7 wt.%Mo. For the destabilized + tempered condition the macro-hardness of the iron with 0.7 wt.%Mo addition was higher than the reference iron due to a finer and denser distribution of secondary-carbides.

Keywords: Destabilization; Electron microscopy; Hardness; High chromium cast irons; Secondary carbides; Tempering.