Using modern concepts in the design of extrusion dies to improve the mechanical extrusion and fatigue properties for AA1100

Abstract

In this research work a direct extrusion unit has been designed and manufactured for circular section using the theoretical die design concepts for designing of the die profile, as constancy of the ratio of successive generalized homogeneous strain increment (CRHS). This was carried out by studying the final mechanical properties of the direct extruded products through dies with theoretical concept (ACRHS) and (UCRHS). Commercial alloy AA1100 round section billets was subjected to uniform extruded compressive load using two types of extrusion dies i.e. (ACRHS) and (UCRHS) at room temperature. The product of these dies with as received were conducted to testing under tensile and fatigue tests without corrosion and with corrosion of 90 days fully submersed in 0.35 % NaСl solution. The experimental results show that the reduction percentage (RP) in the main mechanical properties, UTS, YS and BHN due to corrosion were 14.28 %, 5.88 % and 12.12 % for as received samples, 2.74 %, 5.08 % and 6.12 % for the ACRHS samples and 7.79 %, 6.86 % and 8.88 % for UCRHS samples respectively. It was concluded that the less reduction percentage was occurred in the ACRHS samples compared to other samples. Corrosion fatigue testing of the above three samples were made and compared to the same samples without corrosion. The testing results revealed that the corrosion is significantly reduce the fatigue strength at 107 cycles from 40 to 33.65 MPa for as received samples, from 49.47 to 46.73 for ACRHS samples and from 49.5 to 45.89 MPa for UCRHS samples. The results may be lead to the best mechanical and fatigue properties under corrosion action are the ACRHS samples. The obtained results show that the extrusion die (ACRHS) is the most efficient die design

Identifying regularities of high temperature on constant and variable fatigue life of AA7075-Al2O3 nanocomposite fabricated by stir casting method

“…The high temperature reduced the mechanical properties, the (UTS) reduced from 233 MPa to198 MPa showing 15 % reduction percentage while the Al 2 O 3 improved (UTS) from 198 MPa to 236 MPa showing 16 % improvement and 15.7 % enhancement for (YS) at (150 °C), The same results were found by [6,8]. The improvement in the mechanical properties of the 6 wt % nanocomposite may be related to the less amount of porosity and uniformly distributed of nanocomposite into the matrix [8].…”

“…The papers [5][6][7] focus on the use of ceramic particles, namely SiC and Al 2 O 3 , as reinforcement in aluminum alloys. These studies investigate the effect of particle size and temperature on the behavior and mechanical properties of high-cycle fatigue.…”

“…Increase in wt % of nanoparticles enhanced the mechanical properties of AA7075 when added Al 2 O 3 using stir casting method. The reduction in porosity, grain size and increase in mechanical properties contribute for improvement the fatigue strength and life [6].…”