冷镦线材的退火工艺

介绍紧固件用冷镦线材的退火工艺。退火工艺控制要点:(1)完全退火需加热至Ac3以上28℃,碳素钢选用Ac3以上30～50℃,合金结构钢选用Ac3以上50～80℃。(2)球化退火将中碳钢、低合金钢加热到Ac1以上20～40℃或Ac1以下13～26℃,保温后缓冷至550℃以下、空冷或在Ar1以下长时间等温后冷却。(3)中间退火。再结晶退火是将钢材加热至Ac1以下约13℃,碳素钢一般为650～700℃;去应力退火一般将钢材以100～150℃/h的速度升温至500～650℃,保温2～4 h,随炉缓冷至200～300℃出炉。球化退火工艺节能、环保、生产周期短,是未来紧固件生产和研究的主要方向。

Annealing process of cold heading wire rod

To introduce the annealing process of cold heading wire rod for fastener.The main points of annealing process control are as follows:(1)for full annealing it need heat to above Ac3 28 ℃,carbon steel selects above Ac3 30~50 ℃,alloy structure steel selects above Ac3 50~80 ℃;(2) for spheroidizing annealing,the medium carbon steel and low alloy steel need heat to Ac1 20~40 ℃ or below Ac1 13~26 ℃,then slow cooling to below 550 ℃,air cooling or below Ar1 long time isothermal then to cooling;(3) intermediate annealing,recrystallization annealing is to heat steel below Ac1 about 13 ℃,carbon steel usually about 650~700 ℃,stress relieving is usually to rise temperature to 500~650 ℃ in speed of 100~150 ℃/s,holding 2~4 hours,then cool slowly in furnace to 200~300 ℃ and discharge.Spheroidizing annealing process has the advantage of environmental protection and energy saving,production period short,is main direction of future fastener production and research.