退火处理时工件表面氧化皮的控制

Control of Oxide Skin on Workpieces During Annealing

一种材料为10钢的零件需进行退火处理,硬度要求≤60 HRB,且不能有氧化皮。将该零件放入箱式炉中通入氮气进行退火处理经过多次试验,得出了硬度和表面质量均符合要求的退火工艺为:零件进炉后立即通入200 L/min的氮气,当炉温达到规定的退火温度后减小氮气流量至30 L/min,同时减小炉气的排出量。

One type of part of 10 steel needs to be annealed to hardness of 60 HRB or lower without oxide skin being formed. The parts were annealed in a box furnace provided with nitrogen atmosphere. After being annealed by trial processes many times, an improved procedure by which the parts may be annealed to acceptable hardness and surface quality was follows: nitrogen is introduced at a flow rate of 200 L/min into the furnace immediately after the parts being loaded, and when furnace temperature reaches specified annealing temperature, flow rate of nitrogen is reduced to 30 L/min, and flow rate of atmosphere discharged from the furnace is reduced at the same time.