抗應(yīng)力腐蝕性能的影響
(中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用光學(xué)顯微分析、掃描電鏡及透射電鏡觀察、慢應(yīng)變速率拉伸測(cè)試等研究2056鋁合金在T6、T851及T351熱處理狀態(tài)下的微觀組織和抗應(yīng)力腐蝕性能。結(jié)果表明：2056合金在T6態(tài)下，晶內(nèi)析出相主要為粗大的S′相和少量粗大的含錳相，抗拉強(qiáng)度為445.13 MPa，晶界析出相粗大且呈非連續(xù)分布，無沉淀析出帶(PFZ)為0.1~0.2 µm，應(yīng)力腐蝕敏感性最大；T851態(tài)下，晶內(nèi)析出相主要為細(xì)小彌散的S′相，合金具有最高的抗拉強(qiáng)度，達(dá)到502.01 MPa，晶界析出相呈離散狀分布，PFZ較窄，約為0.02 µm，抗應(yīng)力腐蝕性能優(yōu)于T6態(tài)的；T351時(shí)效狀態(tài)下，晶內(nèi)觀察到大量的位錯(cuò)和位錯(cuò)塞積以及少量GPB區(qū)，抗拉強(qiáng)度為469.73 MPa，介于T6和T851之間，晶界無粗大平衡相析出，無明顯PFZ，抗應(yīng)力腐蝕性能最好。
關(guān)鍵字: 2056鋁合金；熱處理；微觀組織；應(yīng)力腐蝕開裂敏感性
stress corrosion cracking of aluminum alloy 2056
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The microstructure and stress corrosion cracking (SCC) sensitivity of aluminum alloy 2056 were investigated using OM, SEM and TEM observations and slow strain rate tension testing (SSRT) in T6, T851 and T351 conditions. The results show that, in T6 aging condition, the coarsening S′ phase and small amount of coarsening Mn-containing phase are mainly observed in matrix, the ultimate strength of 2056 alloy is 445.13 MPa. The grain boundary precipitates are coarsely and sparsely distributed, and the precipitate free zone (PFZ) is 0.1−0.2 µm. In T6 condition, the stress corrosion cracking sensitivity of 2056 alloy is the largest. In T851 condition, the precipitates are high density of S′ phase in matrix, the ultimate strength of 2056 alloy is 502.01 MPa. The grain boundary precipitates are smaller obviously and discretely distributed, and the PFZ is about 0.02 µm, the corrosion resistance is higher than that in T6 condition. In T351 aging condition, the dislocation pile-up and small amount of GPB zones are observed in matrix, and there are no precipitates and PFZ in grain boundaries. In T351 condition, the ultimate strength of the 2056 alloy is between those of T6 and T851, reaching 469.73 MPa, and the alloy possesses the best resistance to SCC.
Key words: 2056 aluminum alloy; heat treatment; microstructure; stress corrosion cracking susceptibility
