Screw &barrel of an extruder machine 1,Hardness After Hardending&Tempering : HB240~280 2,Nitrided Hardness 1,Standards of single screw and cylinder of exturder machine:20mm--300mm,2,Ratio of length to siameter :L/D=15--55Technical Specification1,Hardness After Hardending&Tempering : HB240~2802,Nitrided Hardness : HV900~9503,Nitrided Case Depth : 0.55~0.7mm4,Nitrided Brittleness :Less Than Grade ...