溫度對Al-Zn-Mg-Cu高強(qiáng)鋁合金靜態(tài)回復(fù)力學(xué)行為的影響

溫度對Al-Zn-Mg-Cu高強(qiáng)鋁合金靜態(tài)回復(fù)力學(xué)行為的影響Influence of Temperature on Mechanical Behavior During Static Restore Processes of Al-Zn-Mg-Cu High Strength Aluminum Alloy

采用雙道次熱壓縮實(shí)驗(yàn)，研究了新型Al-Zn-Mg-Cu高強(qiáng)鋁合金鑄態(tài)試樣在溫度300~400 ℃，應(yīng)變速率0.01~0.1 s-1，變形程度33%+20%，保溫0~900 s靜態(tài)回復(fù)過程中的流變應(yīng)力行為。結(jié)果表明：溫度對該合金靜態(tài)回復(fù)力學(xué)行為影響顯著；（1）300 ℃和330 ℃溫度較低時(shí)，變形過程中回復(fù)較慢，存儲(chǔ)的變形能較高，保溫期間的回復(fù)和再結(jié)晶使第二道次流變應(yīng)力降低，表現(xiàn)為流變應(yīng)力軟化現(xiàn)象，且隨著道次間保溫時(shí)間的延長應(yīng)力的軟化程度增大；保溫過程中析出相的出現(xiàn)減緩了應(yīng)力軟化速率；（2）溫度升高到360 ℃和400 ℃時(shí)，變形過程中回復(fù)充分，存儲(chǔ)的變形能低；變形保溫后基體的固溶度高，第二道次流變應(yīng)力升高，表現(xiàn)為流變應(yīng)力硬化現(xiàn)象；360 ℃變形保溫期間的回復(fù)/再結(jié)晶使得隨著道次間保溫時(shí)間的延長應(yīng)力又逐漸降低軟化，析出相減緩了應(yīng)力的軟化速率；而400 ℃變形保溫期間沒有回復(fù)/再結(jié)晶和析出相，所以硬化后的應(yīng)力并不隨著道次間保溫時(shí)間的延長而發(fā)生變化。

Flow stress behaviors of as-cast Al-Zn-Mg-Cu high strength aluminum alloy during static restore processes were investigated by: Isothermal double-pass compression tests at temperatures of 300-400℃, strain rates of 0.01-1 s-1, strains of 33% +20% with the holding times of 0~900 s after the first pass compression. The results indicate that the deformation temperature has a dramatical effect on mechanical behaviors during static restore processes of the alloy. (1) At 300 ℃ and 330 ℃ lower temperatures, the recovery during the deformation is slow, and deformation energy stored in matrix is higher, flow stresses at the second pass deformation decreased during the recovery and recrystallization, and the stress softening phenomena is observed. Stress softening is increased with the increasing holding time; Precipitation during the holding time inhibites the stress softening. (2) At 360 ℃ and 400 ℃ higher temperatures, the recovery during deformation is rapid, and deformation energy stored in matrix is lower. Solid solubility is higher after holding, so that flow stress at the second pass deformation is increased, stress hardening phenomena is observed. Stress hardening decreased with the increasing holding time duo to the recovery and recrystallization during holding period at 360 ℃; Precipitation during holding also inhibited the stress softening. However, Stress hardening remains constant with the increasing holding time duo to the reasanenal there are no recovery and recrystallization during holding period at 400 ℃.

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