The production of high-speed steel composite rolls includes smelting, molding, pouring, heat treatment, and mechanical processing of the roll body and roll core. The roller body is made of wear-resistant high-carbon high-speed steel, and the roller core material is high-strength ductile iron. The roller body and the roller core are smelted in an electric furnace separately and are usually compounded by centrifugal casting. The process steps are:
1. Molten steel smelting of high-carbon high-speed steel for rolls.
1) Mix ordinary steel scrap, pig iron, ferromolybdenum, Ferro niobium, and ferrochrome according to the required composition of the roll body, put them into the furnace for heating and melting, add ferrosilicon and ferromanganese after the molten steel is melted, and add ferrovanadium before leaving the furnace.
2) After adjusting the ingredients before the furnace, raise the temperature to 1520-1600°C, add 0.10%-0.30% of the weight of molten steel to deoxidize aluminum, and then take it out of the furnace.
3) Break the modifier, rare earth ferrosilicon, and ferrotitanium into small pieces with a particle size of less than 20mm. After drying below 240°C, place them at the bottom of the ladle and use the method of pouring into the ladle to carry out compound modification treatment on molten steel.
2. Hot metal smelting of high-strength nodular cast iron for roller cores.
1) Put ordinary steel scrap, ferrosilicon, ferromanganese, nickel plate, ferromolybdenum, and ferrochrome into the furnace for heating and melting according to the required composition of the roller core, and add carbon with graphite or pig iron.
2) After adjusting the ingredients before the furnace passes the temperature, raise the temperature to 1420-1480°C and release it from the furnace.
3) Break the rare earth magnesium spheroidizer into small pieces with a particle size of less than 18mm, dry it below 180°C, place it at the bottom of the ladle, and use the method of pouring into the ladle to spheroidize the molten iron. When the molten iron enters the ladle, Add less than 1.5% of 75% ferrosilicon alloy for flow inoculation treatment.
3. The technological steps of the roll compounding by centrifugal casting method are:
1) First, pour high-carbon high-speed steel molten steel into the mold rotating on the centrifuge. The pouring temperature of the molten steel is 1420-1450°C, the mold material is HT200, the wall thickness is 80-200mm, the preheating temperature is greater than 200°C, and Spray the paint at this temperature, the thickness of the paint is less than 4mm, and the mold temperature is not lower than 120°C when pouring.
2) Mold speed
Put the high-speed steel composite roll into the annealing furnace, heat it to 880-920°C and keep it warm, and then cool it in the furnace. The hardness is less than HRC35, and then rough machining directly; Temper twice at 500-550°C, hold for 4-12 hours and finally finish the roll to the specified size.