变形量对铸锻复合成形AZ81材料组织与性能的影响

通过对AZ81镁合金挤压铸坯进行等温模锻实验,研究在铸锻复合成形工艺中,不同变形量下锻压过程中材料组织和性能的演变规律.结果表明:在不同变形量下锻压后,材料宏观组织均出现明显的流线型分布,不同变形区在微观上呈现出不同的变形组织;随着变形量的增大,流线型组织增多,大变形区的组织更加细化,动态再结晶过程更加充分,合金综合力学性能大幅提高;当变形量为60%时,材料抗托强度达到278.06MPa,屈服强度达到161.24MPa,伸长率达到11.36%.通过扫描电镜分析,试样的断口均表现为准解理断裂特征;随着变形量的增加,合金由脆性断裂特征为主发展为韧性断裂的特征为主.

Effect of Deforming Degree on. Mechanical Properties and Microstructure of AZ81 Magnesium Alloy in Casting-Forging Compound Forming Process

The microstructure and property evolution of squeeze-cast magnesium alloy AZ81 after die-forging with different compression was investigated. The results show that after forging under different deformation degree,the obvious streamline distribution exists in the macrostructure of all forging samples, and different deforming microstructure exists in different deforming zone; with the increase of deformation, the streamlined structure increases, the organization in large deformation zones even more refines, the dynamic recrystallization process gets more fully and the mechanical properties of AZ81 alloy rises notably; when the deforming degree reaches 60%, the tensile strength is 278.6 MPa, the yield strength is 161.24 MPa and the elongation can be 11.36%. Analyzed by SEM,the fracture presents quasi-cleavage feature; with the increase of deforming degree, the characteristic of fracture changes from brittleness to ductility.