Effect of a Minor Sr Modifier on the Microstructures and Mechanical Properties of 7075 T6 Al Alloys
Shaoming Ma,
Youhong Sun,
Huiyuan Wang,
Xiaoshu Lü,
Ming Qian,
Yinlong Ma,
Chi Zhang,
Baochang Liu
Affiliations
Shaoming Ma
School of Construction Engineering, Jilin University, Changchun 130026, China
Youhong Sun
School of Construction Engineering, Jilin University, Changchun 130026, China
Huiyuan Wang
Key Laboratory of Automobile Materials of Ministry of Education & School of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025, China
Xiaoshu Lü
School of Construction Engineering, Jilin University, Changchun 130026, China
Ming Qian
School of Construction Engineering, Jilin University, Changchun 130026, China
Yinlong Ma
School of Construction Engineering, Jilin University, Changchun 130026, China
Chi Zhang
School of Construction Engineering, Jilin University, Changchun 130026, China
Baochang Liu
School of Construction Engineering, Jilin University, Changchun 130026, China
The influence of a minor strontium (Sr) modifier on the microstructures and mechanical properties of 7075 Al alloys was investigated in this paper. The grain size of cast 7075 Al alloys was refined from 157 μm to 115 μm, 108 μm, and 105 μm after adding 0.05 wt. %, 0.1 wt. %, and 0.2 wt. % Sr, respectively. The extruded 7075 Al alloys was refined with different degrees of Sr modifier. The mechanical properties were optimum when adding 0.1 wt. % Sr. The ultimate tensile strength (σb) increased from 573 to 598 MPa and the elongation-to-failure (δf) was raised from 19.5% to 24.9%. The microhardness increased from 182 to 195 Hv. The tensile fracture surface via scanning electron microscopy (SEM) revealed a transition from brittle fracture to ductile fracture as Sr increased from 0 wt. % to 0.2 wt. %. The result in this paper proved that the modifier can improve the properties of 7075 Al alloy.
