高温退火对电磁纯铁零件尺寸及矫顽力的影响

Effects of high-temperature annealing on dimension and coercivity of soft magnetic iron parts

用真空氢气退火炉对两个批次DT4C纯铁零件进行了高温退火试验,研究了1050~1150℃高温退火温度及不同冷却速度下零件尺寸及矫顽力的变化。结果表明,当采用1050~1150℃高温退火后能明显降低矫顽力,但零件外圆尺寸发生不规则变化,最大收缩率在0.20%左右,最大膨胀率在0.27%左右。矫顽力不合格的零件如尺寸误差能合要求的,可采用1050~1150℃退火降低矫顽力。矫顽力不合格的原材料,先要对毛坯料进行1050~1150℃高温退火,再对机加工后零件进行900℃中温去应力退火。采用1050~1150℃高温退火时,可以将1120℃→900℃过程的冷却速度提高至120℃/h,以缩短零件的处理周期。

High temperature annealing test of two batches of DT4 C pure iron parts was carried out in vaccum hydrogen annealing furnace.Effects of annealing temperature and cooling speed on dimension and coercivity of the parts were investigated. The results show that the magnetic coercive force decreases significantly when the annealing temperature is 1050-1150 ℃,however the dimensions change irregularly within the maximum shrink rate of 0. 20% and the maximum expansion rate of 0. 27%. For the magnetic coercive force unqualified parts,but its size error is meet the requirements,it can be annealed at 1050-1150 ℃ to reduce the magnetic coercive force. For the magnetic coercive force unqualified raw material,the blank should be annealed at 1050-1150 ℃,then the machined parts are subjected to stress relief annealing at 900 ℃. When annealing at 1050 to 1150 ℃,the cooling rate can be increased to about 120 ℃ / h between the temperature range from 1120 ℃ to 900 ℃,in order to shorten the processing cycle.