【摘要】 对高镁Al-10Mg合金分别做了固溶与时效处理,固溶工艺为673 K、24 h,固溶后的高温时效工艺为573 K、24 h,并对固溶及时效态试样分别进行了两道次压缩实验。通过OM、XRD、EPMA、EBSD等分析表征手段,研究了时效析出的b相对高镁Al-10Mg合金热变形过程中的力学性能及微观组织演变的影响。结果表明,时效处理后晶粒内部析出了均匀分布的b相,两道次压缩实验后时效态试样的应力-应变曲线始终处于固溶态试样曲线的下方。第一道次压缩实验中时效态试样的硬化率低于固溶态试样的硬化率,在回复过程中固溶Mg原子对形变强化起主要作用;第二道次压缩实验中时效态试样的硬化率高于固溶态试样的硬化率,时效态试样内部的位错累积更显著并且更早地出现了再结晶软化。时效态试样压缩组织内残余了更多的形变储能,使b相激发出更多的小角度晶界,进而将变形晶粒基体切割成若干区块,促进了再结晶形核,从而细化了再结晶晶粒。时效态压缩组织各区块的Schmid因子分布更均匀,在后续变形过程中能承受更多的塑性变形。再结晶形核不再局限于晶界凸出(bulging)形核,再结晶晶粒不再具备典型的再结晶织构特性,各向异性被弱化。b相阻碍了位错的滑移,将部分变形储能累积在沉淀相周围的小角度晶界处,减少了滑移到变形晶粒晶界处的位错数量,从而减缓了变形晶粒晶格的旋转,使变形晶粒含有{001}和{101}2种面织构组分。更多还原

【Abstract】 Al-Mg series alloy plays an important role in offshore manufacturing, transportation and aerospace industries for its high strength-to-weight ratio, high corrosion resistance and good welding performance. For high magnesium Al-Mg alloy, b phase always acts as a restraint condition to the whole thermal mechanical processing(TMP) procedure. Its positive effect is still unclear. In this work, the effect of coarse b(Al3 Mg2) phase of Al-10 Mg alloy annealed at 573 K for 24 h and applied double passes uniaxial compression on microstructure evolution was studied by using OM,XRD,EPMA and EBSD.The result shows that discrete coarse b phase was precipitated in the interior of grains after 573 K and 24 h annealing treatment.The true stress-true strain curve of annealed sample was lower than that of solution treated one.Hardening rate of annealed sample was lower in first compression pass,and conversely higher than that of solution treated one in the second pass.Solution Mg atoms play an important role in strain hardening during dynamic recovery.Dislocation slipping was obstructed by coarse b phase,and then low angle boundary(LAB)was stimulated near coarse b phase.Not just bulging nucleation mechanism working,dynamic recrystallization nucleation was stimulated and microstructure was refined.Since part of deformation-stored energy was lured away by LAB,lattice rotation of deformed grains were weakened possessing{001}and{101}textures simultaneously.Schmid factors of three blocks with different lattice orientations were calculated,which suggested that alloy can load more plastic deformation after annealing treatment.Texture of recrystallized new grains was weakened at the same time.Microstructure anisotropy could be controlled by coarse b phase in TMP.更多还原