【摘要】 对常规压铸(DC)和真空压铸(VDC)Al-Mg-Si-Mn合金平板铸件的微观组织、力学性能和疲劳性能进行研究,并且用SEM和EDS等手段分析了断口形貌。结果表明:Al-Mg-Si-Mn合金的微观组织主要由初生α-Al,[Al+Mg2Si]共晶区以及Al15(Fe,Mn)3Si2颗粒构成。常规压铸试样和真空压铸试样的抗拉强度(Rm)、屈服强度(Rp 0.2)、弹性模量(E)和伸长率(A)分别为321 MPa,205 MPa,54 MPa和3.9%,以及331 MPa,210 MPa,55 MPa和4.4%。真空压铸试样的裂纹扩展速率曲线斜率(2.824)低于常规压铸试样(3.693),因而真空压铸试样的抗疲劳性能较好。试样的拉伸断口显示出大量脆性断裂特点即解理平面,而疲劳断口则可清晰观察到疲劳条纹和撕裂棱。更多还原

【Abstract】 Microstructure,mechanical properties and fatigue crack growth of die cast( DC) and vacuum die cast( VDC) thin-walled AlMg-Si-Mn alloy samples were studied. Results indicate that microstructure of the alloy consists of primary α-Al,eutectic [Al + Mg2Si] and Al15( Fe,Mn)3Si2particles. Tensile strength,yield strength and elongation of DC and VDC samples are 321 MPa,205 MPa,3. 9% and 331 MPa,210 MPa,4. 4%,respectively. Crack growth rate of the VDC samples is slightly lower than that of DC samples,thus the fatigue resistance of VDC samples is superior. Numerous cleavage facets are observed in tensile fracture surface. Fatigue striations and tear ridges are widely observed in fatigue fracture surface.更多还原