高强度螺栓用35CrMo免退火冷镦钢热轧盘条的研制

Development of Hot-Rolled Wire Rods of 35CrMo Annealing-Free Cold Heading Steel for High-Strength Bolts

通过入减定径温度780℃,入减定径减面率42%(Φ18.4 mm→Φ14 mm),冷却速度0.42℃/s,35CrMo钢热轧材显微组织为F+P,铁素体含量≥40%,实际晶粒度10~11级,抗拉强度≤750 MPa,断面收缩率≥60%,硬度值214~225HV,实现免退火直接进行大减面率拉拔。

By controlling billet temperature 780℃as entering sizing mill,sizing reducing rate 42%(Φ18.4 mm→Φ14 mm),cooling rate 0.42℃/s,the microstructure of 35CrMo steel hot-rolled rod is F+P,with ferrite content more than 40%,actual grain size 10-11,tensile strength 750 MPa,reduction of area≥60%,and hardness value 214-225HV,to realize annealing-free large reduction of cross-sectional area cold drawing.