Effects of Cryogenic Forging and Anodization on the Mechanical Properties of AA 7075-T73 Aluminum Alloys

Abstract

In this study, high-strength AA7075 alloy samples were cryogenically forged after annealing and then subjected to solution and aging treatments. The cryogenically forged 7075-T73 alloy samples displayed equiaxed fine grains associated with abundant fine precipitates in their matrix. Compared with conventional 7075-T73 alloy samples, the cryogenically forged samples exhibited an 8-12% reduction in tensile strength and an increased fatigue strength and higher corrosion resistance. The fatigue strength measured at 10 7 cycles was 225 MPa in the bare samples; the strength was increased to 250 MPa in the cryogenically forged samples. The effect of anodization on the corrosion resistance of the bare samples was improved from (E corr ) 20.80 to 20.61 V.

The Optimum Process to Produce High-Strength Cast/Forged Al–8%Zn–2.5%Mg–1%Cu Alloy

“…The anodized/sealed SO sample demonstrated a relatively lower Icorr than the anodized/sealed HC sample (an SO sample of 3.29 × 10 −6 A/cm 2 compared with an HC sample of 7.97 × 10 −6 A/cm 2 ). This material also displayed corrosion resistance comparable with that of anodized/sealed extruded AA7075-T73 bar samples; Ecorr: −0.91 V for the SO sample and −0.61 for the extruded bar sample, Icorr; 3.29 × 10 −6 A/cm 2 for the SO sample and 3.9 × 10 −6 A/cm 2 for the extruded bar [11]. No pitting was observed in both anodized/sealed SO and extruded AA7075 bar samples.…”

“…Forging Al alloys could offer good tensile strength (≥300 MPa) and high elongation (≥10%) and fatigue strength (≥120 MPa at 1 × 10 7 cycles) [11][12][13]. The forged parts are widely used in the automotive industry.…”

“…The concept of the cast/forge process was proposed by Fujikawa et al [14] Chang et al introduced the cast/forge hybrid process to reduce the porosity of 7075 aluminum alloy castings [15]. The tripods produced with this process were shown at ALUMINUM CHINA 2018, Shanghai, New International Expo Centre (2018/07/ [11][12][13]. The block castings were used instead of extruded bars or plates to decrease the processing cost.…”