【摘要】 SWRCH35K冷镦钢盘条制作高强度螺栓过程中表面出现麻点。12 mm SWRCH35K盘条金相组织为铁素体和珠光体,铁素体晶粒度8.5级,未见明显脱碳层,经765℃退火后酸洗,冷拔至11.15 mm,表面出现麻点,组织为铁素体和珠光体,铁素体晶粒度9级,边部出现深度为0.36 mm的全脱碳层。分析表明:盘条退火时温度偏高或加热时间过长,晶粒异常长大从而引起塑性变形不均匀,随后的冷拔变形量不大,使盘条表面的粗晶遗传至下道工序,冷镦时由于表面粗晶处的强度低,造成麻点。建议用户控制退火后的盘条质量,控制好晶粒度,确保正确使用和加工盘条。更多还原

【Abstract】 The pits occurred on the surface while high strength bolt was produced by using SWRCH35K cold heading wire rod.The microstructure of diameter 12 mm wire rod is ferrite and pearlite.Grain size of ferrite is grade 8.5,there isn’t obvious decarburized layer.It was drawn diameter 11.15 mm after 765 ℃ annealing and pickling.Pits occurred on the surface,microstructure is ferrite and pearlite,ferrite grain size is grade 9,complete decarburization depth is 0.36 mm occurred on edge.Analysis shows that the annealing temperature is high and heating time is too long,grain size growing caused plastic deformation uneven,next cold drawn deformation amount is small,coarse grain on the surface inherit to next procedure,the reason that strength of surface coarse grain is low causes pit.It is suggested that customers control wire rod quality after annealing,control grain size to assure the correct usage and processing of wire rod.更多还原