细晶非调质钢紧固件生产现状

采用细晶非调质钢线材制造紧固件,不需调质处理,可避免整体的弯曲变形,节能降耗明显。细晶非调质钢紧固件材料牌号主要有MFT8,MFT9,MFT10。通过热机械轧制控温控冷生产的MFT8钢线材,组织是铁素体和珠光体,平均晶粒度为12级,尺寸约5μm。MFT8钢线材除了具有高强度、高塑性,还有优异的抗冲击韧性和抗低温疲劳性能,特别适合制造8.8级高强度螺栓。采用MFT8钢线材制造紧固件时,拉拔总压缩率控制在22%～35%,最佳总压缩率约30%,可省略前处理退火工序和调质处理工序,增加与表面处理相结合的稳定化时效处理工序,处理温度200～400℃,时间0.5～2 h。

Production present situation of fine grain non-heat treatment steel fastener

There is no need to be quenched and tempered while fastener is produced by using fine grain non-quenched and tempered steel wire rod, which can avoid overall bending deformation, energy saving and consumption reducing are obvious. The material brand of fine grain non-quenched and tempered steel fastener is mainly MFT8, MFT9 and MFT10. The microstructure of MFT8 wire rod produced by TMCP controlled temperature and controlled cooling is ferrite and pearlite, average grain size grade is 12, size is about 5 μm. MFT8 wire rod has properties of high tensile strength, high plasticity, good impact toughness and low temperature resistance fatigue properties, which is suitable for producing 8.8 grade high tensile strength bolts. The drawing total compressibility is controlled from 22% to 35%, the best is about 30%, pre-treatment process and quenched and tempered treatment process can be avoided, stabilizing aging treatment process combined with surface treatment is added, treatment temperature is 200 - 400℃, time is 0.5 - 2 h when fastener is produced by using MFT8 wire rod.