Effects of Heat Treatment on the Mechanical Properties and Microstructure of AA7075/AlSi10Mg Sandwich Produced by Direct Metal Laser Sintering
摘要
The present study investigates the effect of heat-treatment on the mechanical response of additively manufactured AA7075/AlSi10Mg dissimilar alloy sandwich specimens produced by Direct Metal Laser Sintering. Further, the SWS is subjected to three different heat-treatment conditions namely HT 1-SWS (Solution heat treatment 350 °C for 2 h + artificial aging 180 °C for 12 h), HT 2-SWS (Solution heat treatment 400 °C for 2 h + artificial aging 180 °C for 12 h) and HT 3-SWS (Solution heat treatment 450 °C for 2 h + artificial aging 180 °C for 12 h) and the corresponding changes in mechanical and metallurgical characteristics of the SWS is studied post heat treatment. The tensile properties, including percentage elongation and ultimate tensile strength of the as-built (AB-SWS), HT 1-SWS, HT 2-SWS and HT 3-SWS specimens were systematically evaluated and compared. Among the tested conditions, the HT 3-SWS specimen exhibited the highest yield strength compared to the AB-SWS, HT 1-SWS and HT 2-SWS samples. The ultimate tensile strength values for the AB-SWS, HT 1-SWS , HT 2-SWS and HT 3-SWS specimens were measured as 223, 198.5, 239.3 and 141.7 MPa respectively. Additionally, the HT 1-SWS specimen demonstrated the highest microhardness value of 138.4 Hv, exceeding those of the as-built, HT 2-SWS, and HT 3-SWS specimens. Overall, the results underscore a strong impact on the microstructure with the post heat treatment of the DMLS specimens. It was found that the intermediate heat treatment (350-450 °C) optimizes the compromise between strength and ductility, whereas 450 °C induced the over-aging and performance deterioration due to the grain size and Si particles precipitated inside the microstructure during the heat treatment. These results give clarification for tailoring post-processing strategies for dissimilar alloy sandwich specimen in advanced lightweight applications.