(中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用拉伸力學(xué)性能測(cè)試、電導(dǎo)率測(cè)定、晶間腐蝕實(shí)驗(yàn)及透射電鏡分析等手段研究雙級(jí)時(shí)效處理?xiàng)l件下6156鋁合金的力學(xué)性能、電導(dǎo)率、晶間腐蝕和顯微組織結(jié)構(gòu)，采用正交實(shí)驗(yàn)優(yōu)化雙級(jí)時(shí)效工藝。結(jié)果表明：在本研究范圍內(nèi)，6156鋁合金雙級(jí)時(shí)效的四因素中第一級(jí)時(shí)效制度對(duì)合金的力學(xué)性能和電導(dǎo)率影響不大，第二級(jí)時(shí)效溫度和時(shí)間是影響合金最終性能的主要因素。對(duì)于6156鋁合金，最佳雙級(jí)時(shí)效工藝為(175 ℃，6 h)+(210 ℃，5 h)，相對(duì)于T6態(tài)，合金強(qiáng)度稍有降低，電導(dǎo)率上升，腐蝕類型也由晶間腐蝕轉(zhuǎn)變?yōu)辄c(diǎn)蝕，腐蝕深度明顯變淺。電鏡觀察結(jié)果表明：雙級(jí)時(shí)效處理后，晶內(nèi)析出大量的Q′相，晶界析出相球化且析出相之間的間距增大，呈斷續(xù)分布，無沉淀析出帶(PFZ)變寬，這種微觀結(jié)構(gòu)能有效提高6156合金的電導(dǎo)率和腐蝕性能，同時(shí)使合金具有較高的強(qiáng)度。
關(guān)鍵字: 6156鋁合金；雙級(jí)時(shí)效；力學(xué)性能；電導(dǎo)率；晶間腐蝕；微觀組織
microstructure and properties of 6156 aluminum alloy
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effects of two-step aging treatment on the mechanical properties, electrical conductivity, intergranular corrosion and microstructure of 6156 aluminum alloy were investigated by means of tensile, conductivity measurement, intergranular corrosion experiments and transmission electron microscopy (TEM). The orthogonal test results show that the pre-aging has no obvious effect on the mechanical properties and electrical conductivity, and the second step aging temperature and time are the key factors in double aging parameters, which mainly decide the final properties of 6156 alloy. Under the optimum two-step aging treatment of (175 ℃, 6 h)+(210 ℃, 5 h), the ultimate strength decreases slightly and the electrical conductivity increases. The mode of corrosion changes from intergranular corrosion to pitting corrosion while the corrosion depth decreases obviously. The TEM observation results show that after two-step aging treatment, there are plenty of Q′ precipitates in matrix, and the coarse and isolate precipitates present in grain boundaries and the PFZ is broaden, which contribute to improve the electrical conductivity and corrosion resistance while the tensile strength decreases a little.
Key words: 6156 aluminum alloy; two-step aging; mechanical properties; electrical conductivity; intergranular corrosion; microstructure
