What are the basic processes involved in producing high speed steel rolls?

The production of HSS composite rolls includes melting, molding, casting, heat treatment and machining of roll body and core. The roller body is composed 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 respectively melted by electric furnace, and are usually formed by centrifugal casting method. The process steps are as follows:

1. Molten steel smelting of roller height carbon high speed steel.

1) Put ordinary scrap steel, pig iron, ferro molybdenum, ferro niobium and ferrochrome into the furnace according to the required roll composition, heat and melt, add ferrosilicon and ferromanganese after molten steel, add ferrovanadium before baking.

2) Before the furnace adjust the composition qualified after the temperature rose to 1520-1600℃, add 0.10%-0.30% of the weight of molten steel aluminum deoxidization, and then out of the oven.

3) The modifier, rare earth ferrosilicon and ferrotitanium were broken to small pieces with particle size less than 20mm, dried at 240℃, placed at the bottom of the ladle, and compound metamorphic treatment of molten steel was carried out by the ladle punch method.

2. Roll core high strength nodular cast iron smelting.

1) Put ordinary scrap steel, ferrosilicon, ferromanganese, nickel plate, ferromolybdenum and ferrochrome into the furnace to heat and melt according to the required components of the roller core, and use graphite or pig iron to carburize.

2) Before the furnace, adjust the composition and raise the temperature to 1420-1480℃.

3) The rare-earth magnesium spheroidizing agent is broken to small pieces with particle size less than 18mm, dried below 180℃, and placed at the bottom of the ladle. The molten iron is spheroidized by the ladle thrusting method. When the molten iron is poured into the ladle, 75% ferrosilicon alloy less than 1.5% is added for flow inoculation treatment.

3. The process steps of the roller composite by centrifugal casting method are:

1) First, the high carbon high speed steel molten steel is poured into the casting mold rotating on the centrifuge. The casting temperature of molten steel is 1420-1450℃, the casting profile is HT200, the wall thickness is 80-200mm, the preheating temperature is greater than 200℃, and the coating is sprayed at this temperature, the coating thickness is less than 4mm, and the casting mold temperature is not less than 120℃.

2) Casting speed

The HSS composite roller is placed in the annealing furnace, heated to 880-920℃ after heat preservation, the furnace is cold, the hardness is less than HRC35, and the rough processing is carried out directly. Then, it is kept at 1000-1080℃ for 3-8h, then cooled by air or fog, and tempered twice at 500-550℃ for 4-12h. Finally, the roller is finished to the specified size.