Effect of the Matrix, Graphite and Ferrochrome-Manganese Contents in SAW Fluxes, Obtained with Steel Slag and Rice Husk Ash, on the Chemical Composition and Hardness of the Metal Deposited in One Layer

Abstract:

The effect of the matrix, graphite and ferrochrome-manganese contents in SAW fluxes, obtained with steel slag and rice husk ash, on the composition and hardness of the metal deposited in one layer is addressed. Links were established between the flux composition variables (X₁ - Matrix (72.99% slag, 20.44% rice husk ash and 6.57% fluorite), X₂- Graphite and X₃- Ferrochrome-manganese) and the contents of carbon, chromium, manganese, silicon, the microhardness and the hardness of the deposit and metallographic images were acquired. The best flux deposit was characterized metallographically and was evaluated by a microabrasive wear test with a free rotating sphere, using a commercial reference deposit. It is concluded that the carbon content, the microhardness and the hardness of the deposited metal are ruled by graphite and that the chromium, manganese and silicon contents are governed by ferrochrome-manganese; that the best flux corresponds to 88% matrix, 7% graphite and 5% ferrochrome-manganese, with a deposit hardness of 59 HRc, and with martensite and interdendritic austenite microstructure. This behaves properly to wear, being 6% less resistant than the reference.

Key-words:
Flux; SAW; Hardfacing; Steel slags