Comparative Analysis of the Microstructural Features of 28 wt.% Cr Cast Iron Fabricated by Pulsed Plasma Deposition and Conventional Casting
Abstract
The effect of pulsed plasma deposition (by an electrothermal axial plasma accelerator) followed by post-heat treatment on the structure and microhardness of a 28 wt.% Cr white cast iron is analyzed and discussed with respect to the microstructure of the conventionally cast monolithic counterpart. The cast iron (as deposited on a 14 wt.% Cr cast iron substrate) had a microhardness of 630-750 HV0.05; it had layered light contrast/dark contrast structure where dark contrast layers contain fine carbide network. Pulsed plasma deposition followed by heat treatment resulted in a substantial refinement of the microstructure: eutectic M7C3 coarse acicular plates in the conventional cast iron were replaced by fine M7C3, M3C2, M3C particles (Cr depleted in favor of Fe), while the initial carbide particle of 2-3 μm was reduced to 0.6 μm. Secondary dendrite arm spacing decreased from 15 to 1.3 μm, accordingly. The carbide volume fraction in the post-heat-treated coating remarkably increased with respect to the conventional counterpart resulting in a substantial increase in the coating hardness (1300-1750 HV0.05). The heat-treated coating displayed higher resistance to three-body abrasion than the as-deposited coating and similar resistance with that of the conventionally cast iron.
- Publication:
-
Journal of Materials Engineering and Performance
- Pub Date:
- February 2018
- DOI:
- 10.1007/s11665-017-3102-z
- Bibcode:
- 2018JMEP...27..379C
- Keywords:
-
- abrasive wear;
- high-chromium cast iron;
- microhardness;
- microstructure;
- post-heat treatment;
- pulsed plasma deposition