用低碳—Si—Mn—V系热轧双相钢棒材生产高强度紧固件的研究

A Study of Using ■ Rolled Dual Phase Steel of Low Carbon-Si-Mn-V Series to Make High Strength Fastening Piece

本文对低碳—Si—Mn—V 系热轧双相钢经冷变形强化代替中碳钢经热处理强化生产高强度紧固件进行了研究.试验结果指出,采用1200℃加热,1150℃初轧,900～950℃终轧后空冷可得到 F+M 及 B 双相组织,第二相的体积分数约占15～20%,热轧态σ_b>550Mp_a, ψ >64%,δ为26—37%.经29～33%的冷拨变形σ_b 可达800～1100Mp_a,ψ >61%,δ>10%.该钢在热轧态可直接冷镦10级螺母;经适当冷拨强化后可生产8.8级螺栓和螺柱.

It was studied that the.high strenggh fastening piece is made of hot rolled dual phase steel of low carbon-Si-Mn-V series by cold deformation to substitute mid carbon strengthened by heat treatment.The experimental results show that the structure of the steel is ferrite plus martensite and bainite when it was rolled by heating to 1200℃,first-rolling at 1150℃,last- rolling at 900 to 950℃ then in air cooling to get F+M and B dual phase structure.The volume fraction,of second phase is about 15 to 20%,σ_b>550 Mpa, Ψ>64%,δ equals 26 to 37% for heat rolling condition.After 29 to 33% of cold deformation,σ_b can attain 800 to 1100 Mpa,Ψ>61%,δ>10. The 10 grade high-strength nuts can be made of the steel bar by cold-heading directly and 8.8 grade high-strength bolt and screw column can be made by proper cold drawing.