The Structure and Properties of Hardening Coatings of Low-Chromium Hard Alloys for Agricultural Machine Parts

Abstract

A new surfacing material consisting of the Fe-Si-Cr-Cu-C-B system sparingly alloyed with chromium is proposed for agricultural machine parts hardening by induction surfacing method capable to replace the currently widely used materials like Sormite No. 1, 2, PG-US25/27 and those similar to them. The chromium content in the new material is 4.3 %, which is 3-8 times less than that in analogs. The new material was obtained metallurgically, its phase, chemical composition and properties were investigated. The main phase of the alloy is Ferrosilide FeSin, along the grain boundaries of which a carbide phase is precipitated represented by small particles of Cr2C3, Cr7C3 carbides of regular and acicular shapes, as well as large particles of special chromium carbides (Cr,Fe)7C3, (Cr,Fe)23C6. In terms of the relative content, the carbides present in the new material can be conventionally arranged in the following series: (Cr,Fe)23C6 > (Cr,Fe)7C3 > Cr7C3 > Cr2C3.