700MPa管线钢热压缩变形及组织研究

A Study on Thermal Compression Deformation and Structure of 700 MPa Pipeline Steel

利用Gleeble-3500型热模拟机,研究700 MPa管线钢(/%:0.07C,0.90Si,0.60Mn,0.008P,0.002S,0.30Ni,0.10Cr,0.12Mo,0.06V,0.03Nb,0.28Cu,0.04Alt,0.006 0N)20 mm热轧板在850~1 250℃和应变速率0.01~1 s^(-1)下单道次热压缩变形及组织演变,得出单道次压缩变形真应力-真应变曲线,热压缩再结晶动态图和动态再结晶开始时间与变形温度关系(RTT)曲线。研究结果表明,发生再结晶由变形温度和应变速率共同决定,该700 MPa管线钢在温度1 100~1 250和应变速率0.01~0.1 s^(-1)下压缩变形时容易发生再结晶。再结晶发生机制是热压缩应变,使得原始晶粒破碎、新晶界产生迁移促使新晶核生成。

With using Gleeble-3500 thermal simulator the single pass hot compression deformation and structure evo- lution of 20 mm hot-rolled plate of 700 MPa pipeline steel （/%： 0. 07C, 0.90Si, 0. 60Mn, 0. 008P, 0. 002S, 0. 30Ni, 0. 10Cr, 0. 12Mo, 0. 06V, 0.03Nb, 0. 28Cu, 0.04Ah, 0. 006 ON） with strain rate 0. 01 - 1 s-l at 850 - 1 250 ℃ have been studied to get single pass real stress-strain curves, hot compression dynamic recrystallization diagram and relation be- tween dynamic reerystallization initial time and deformation temperature （RTF） curves. Research results show that deform- ation temperature and strain rate make certain of initial recrystallization, the 700 MPa pipe line steel easily occurs dynamic recrystallization with strain rate 0. 01 - 0. 1 s-1 at 1 100 - 1 250 ℃. the recrystallization mechanism is hot compression causing the original grain crushing and the new grain boundary migrating to prompt formation of new crystal nucleus.