Influence of heat treatment and its sequence on elevated-temperature properties of Al-Mn-Mg 3004 alloy

Abstract

Various heat treatments with different sequences between the peak precipitation treatment (375°C/48h, referred to as "P") and the high temperature treatment (450-600 °C, referred to as "H") were performed in Al-Mn-Mg 3004 alloys to simulate their thermal treatments during thermomechanical fabrication processes in the present work. Their influences on the dispersoid precipitation and elevated-temperature properties (yield strength and creep resistance at 300 °C) were investigated. The results indicate that the size of dispersoids increased while the volume fraction of dispersoids decreased with increasing "H" temperature when "P" was performed either prior to or after "H" (denoted as "PH" and "HP", respectively), which results in the reduction of the elevatedtemperature properties. However, the yield strength and creep resistance after "PH" treatments were always higher than those after "HP" treatments at the same "H" temperature. When the "H" temperature during "PH" treatments is controlled below 500°C, the materials can still maintain the appropriate yield strength and creep resistance, providing the possibility for Al-Mn-Mg 3004 alloy to adapt to the conventional fabrication processes but still maintain high elevated-temperature properties.

Improvement of elevated-temperature strength and recrystallization resistance via Mn-containing dispersoid strengthening in Al-Mg-Si 6082 alloys

“…For Alloy B (0.5% Mn), the highest value of YS is 55 MPa at 400 ℃/2 h and 450 ℃/2 h. For Alloy C (1%Mn), the highest YS is 70 MPa under 350 ℃/24 h and 400 ℃/2 h conditions compared to 30 and 28 MPa for Alloy A under such conditions, which represents a more than 130% improvement in the YS at 300 ℃, confirming the essential contribution of the precipitation of dispersoids on the elevated-temperature strength [14] . With the increasing heat treatment temperature, a gradual decrease in YS is observed for Alloy C at 450 ℃/2 h and 450 ℃/16 h, whereas the YS of Alloy B decreases slightly at 450 ℃/16 h due to the coarsening of dispersoids at high temperature [5,23] . On the other hand, the difference in YS between Alloy B and Alloy C also changes with the precipitation treatment conditions.…”

Evolution of Elevated-Temperature Strength and Creep Resistance during Multi-Step Heat Treatments in Al-Mn-Mg Alloy

“…It is reported that the yield strength of 3003 at room temperature (RT) after 375°C/24h has been improved to 80 MPa compared with 52MPa after 600°C/24h due to precipitation of dispersoids [7]. Recently, present authors have systematically studied the evolution of dispersoids at relative lower heat treatment temperature (300-425°C) and their influence on elevated-temperature properties in AlMn-Mg 3004 alloys [6,[8][9][10][11][12]. It is found that high volume fraction and well distributed α-Al(MnFe)Si dispersoids are observed after treated at 375°C for 48h, leading to the remarkable improved YS and creep resistance at elevated-temperature.…”

Enhanced dispersoid precipitation and dispersion strengthening in an Al alloy by microalloying with Cd

“…With a comparable thermal stability to the expensive Sc-containing dispersoids, the nano-sized Mn(Fe)-containing dispersoids have the potential to be developed as a cheaper solution for designing high-temperature Al alloys [17,18]. AA3xxx and some Mn-containing 5xxx and 6xxx Al alloys are normally supersaturated with Mn in the as-cast state [19][20][21].…”

“…In recent years, the dispersion hardening effect of Mn(Fe)-containing dispersoids has been re-assessed. It is found that a proper heat treatment can produce a higher number density of nano-sized α-Al(Mn,Fe)Si dispersoids and therefore a significant dispersion hardening [17][18][19]27,[33][34][35]. For example, by an isothermal annealing at 375 °C for 24 h, the yield strength of AA3003 alloy could be increased by 53.8% in comparison to the as-homogenized sample (600 °C, 24 h) [19].…”