HARDENING OF STEEL AND CAST IRON PARTS THERMOREGULATE MIXTURES

Abstract

The actual problem is the creation of cheap termoregulyatsii mixtures can strengthen the working bodies pecoupon technology. If you have an external source of heat applied to mixtures initiated and supported exothermic reaction, resulting in stable carbides are synthesized and released iron that binds the carbides in dense and strong monolith. To determine the composition of mixtures the calculations and the results obtained thermochemical parameters for the two types of ferro-alloys at various mass contents of carbon in cast iron – from 2.2 to 6.2%..

Significantly increases the strength, hardness and wear resistance of the surface layer of the addition as an alloying element, chromium and vanadium (Cr and V), due to the formation of carbides in the exothermic reaction.

The goal of the study was to design events to create such a mixture and use it with thermal hardening of parts. The mixture powder of low-carbon ferrochromium – ground chips of white cast iron was applied to the parts in the form of dross. Layer, formed, dried, and then heated with a torch until the initiation of the exothermic reactions, and provide the liquid-solid state. These reactions significantly smooth the temperature gradient across the thickness of the layer and contribute to the full preparando latest to metal parts. The formation of two-phase mass melt–carbides with very low rdataset, compared with single-phase liquid state at normal layer coating prevents "slipping" of the masses with inclined surfaces that are strengthened (if the tilt angle is small).

The analysis of the microstructure of the deposited layer showed that he has a fine-grained structure, in line with the principle Sharpie: a mixture of solid soft iron carbides and the matrix structure of pearlite, sorbite or troostite, depending on the cooling rate. Has a high hardness in the range of HRC 52 to 63 HRC.

The se mixtures can be used in case of gas-thermal surface hardening of parts.