热轧变形量对Ti551合金再结晶与织构演化的影响OA

As a representative thermomechanical processing step,hot rolling can generate texture evolu-tion that is critical to the strength-ductility synergy of titanium alloys.Ti551 is a newly developed medi-um-strength,high-toughness alloy designed for deep-sea service;however,its texture-evolution behavi-or during rolling remains unclear.In this work,Ti551 as-forged billets were hot rolled at near β-transus temperature region(Tβ,950℃)with reductions from 5%to 50%.Electron backscatter diffraction(EBSD)was used to quantitatively analyze the fractions of low-angle grain boundaries(LAGBs),grain orientation spread(GOS)and the evolution of α{0001}texture.The results show that,taking the an-nealed condition(0 reduction)as the reference,when the cumulative reduction increases from 0 to 30%,the area fraction of recrystallized/strain-relieved regions decreases from～55%to～36%,and remains nearly unchanged as the reduction is further increased to 50%.In addition,hot rolling develops a basal texture,but its overall intensity decreases with increasing reduction(i.e.,the peak intensity drops and the texture becomes more diffuse).These finds indicate that under near Tβ condition,when the rolling direction is perpendicular to the dominant texture direction of the forged billet,a higher cumulative re-duction is more effective in weakening the basal texture and dispersing the orientation peaks.This can help select the final-pass reduction to obtain a basketweave microstructure with smaller orientation-cluster length scales and improved microstructural uniformity.