6082-T6铝合金的微观组织与拉伸断裂的关系

Relationship between microstructure and tensile fracture of 6082-T6 aluminum alloy

采用静态拉伸的方法,研究了时效态6082-T6铝合金的力学性能。利用光学显微镜(OM)、透射显微镜(TEM)观察了合金的微观组织,利用扫描电镜(SEM)对拉伸断口形貌进行了研究,利用电子探针(EPMA)分析了析出相的分布。通过以上方法分析了时效态6082-T6铝合金的微观组织与拉伸断裂间的关系。结果表明:时效态6082-T6铝合金的屈强比高,抗拉强度为345 MPa,屈服强度为326 MPa;该铝合金中分布有球形凹坑状黑色的Mg2Si析出相,同时还存在白色的α-Al MnFeSi等富铁夹杂相;时效态6082-T6铝合金的拉伸断口呈明显的韧窝型断裂特征。位错塞积产生的应力集中超过弱界面结合强度时,合金的基体就会发生局部区域的断裂,从脆硬的析出相颗粒周围断裂形成坑状的韧窝,最后形成包含有硬脆夹杂相颗粒的韧窝型断裂。

Mechanical properties of the aged 6082-T6 aluminum alloy were studied by means of static tensile method.The microstructure of the alloy was observed by means of optical microscopy(OM)and transmission microscopy(TEM).The tensile fracture morphologies were studied by means of scanning electron microscopy(SEM),and precipitated phase distribution of the alloy was analyzed by means of electronic probe(EPMA).The relationship between microstructure and tensile fracture was comprehensively analyzed.The results show that the aged 6082-T6 aluminum alloy has high yield ratio,of which the tensile strength is 345 MPa and yield strength is 326 MPa.The spherical pit-like black Mg2Si precipitated phase is distributed in the aluminum alloy,meanwhile white iron-rich inclusion phase α-Al MnFeSi is also present.Tensile fracture of the aged 6082-T6 aluminum alloy has obvious dimple-type fracture characteristics.When the stress concentration caused by dislocation pile-up exceeds the weak interface bonding strength,local fracture of the alloy matrix will occur,and pit-like dimples will be formed from the fracture around the brittle precipitated phase particles,and finally dimple-type fracture will form,containing hard and brittle inclusions.