Fully Consolidated Deposits from Oxide Dispersion Strengthened and Silicon Steel Powders via Friction Surfacing

Abstract

The objective of this work is to study the ability of friction surfacing to deposit metal alloys that are difficult to process with traditional methods. Creep and neutron irradiation-resistant oxide dispersion strengthened (ODS) materials cannot be produced via the conventional casting route due to the insolubility of the oxidic and metallic alloy constituents, causing unintended inhomogeneous oxide dispersion and material behavior. Increasing the silicon content of iron–silicon (Fe–Si) improves electromagnetic properties but embrittles the material significantly, and fusion-based manufacturing methods are unable to process this steel. The solid-state nature of the friction surfacing process offers a potential alternative processing route to enable wider usage of difficult-to-process alloy systems. Both ODS and Fe–Si materials are available in powder forms. While the existing literature in friction surfacing focuses on depositing composites by incorporating small quantities of powders through holes in consumable rods, this is the first study showing that a large charge of powder can be converted to a homogeneous fully consolidated deposit in friction surfacing. A novel methodology is used that incorporates the high portion of powder feedstock into hollow consumable friction surfacing rods (up to 35% volume fraction). It was found that fully consolidated deposits can be produced with powder feedstocks using the proposed methodology. A recrystallized, homogeneous, equiaxed microstructure was observed in Fe–Si 6.8 wt% and a new-generation FeAlOY ODS alloy deposits processed with hollow stainless steel friction surfacing rods. Both powder and rod material plasticize and deposit without bulk intermixing.