Zn含量对Al-Mg-Si-Cu合金拉伸性能及晶间腐蚀敏感性的影响  

Tensile Properties and Intergranular Corrosion Sensitivity of Al-Mg-Si-Cu Alloy with Different Zn Coatents

作　　者：陈天宇 章宇豪 王芝秀 李海[1,2] 柏玉吉 王雨航[1] Chen Tianyu;Zhang Yuhao;Wang Zhixiu;Li Hai;Bai Yuji;Wang Yuhang(School of Materials Science and Engineering,Changzhou University,Changzhou 213164,China;JiangsuKey Laboratory of Materials Surface Science and Technology,Changzhou University,Changzhou 213164,China)

机构地区：[1]常州大学材料科学与工程学院,江苏常州213164 [2]常州大学江苏省材料表面科学与技术重点实验室,江苏常州213164

出　　处：《稀有金属》2023年第4期484-492,共9页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(52171029);江苏省高等学校自然科学研究重大项目(18KJA430002)资助。

摘　　要：采用拉伸测试、浸泡腐蚀试验、差示扫描量热(DSC)、扫描电镜(SEM)及透射电镜(TEM)等手段,研究了Zn含量(0~1.2%,质量分数)对自然时效(T4)和峰值时效(T6)状态Al-Mg-Si-Cu合金拉伸性能和晶间腐蚀敏感性的影响。结果表明:较低的Zn含量(0~0.8%)对T4和T6合金强度无显著影响;T4合金无晶间腐蚀敏感性,而T6合金发生严重晶间腐蚀且最大腐蚀深度随Zn含量增加而下降,并于0.8%Zn含量时降至320μm,较无Zn合金减小220μm。当Zn含量增大至1.2%,晶内预脱溶原子偏聚区(GP区)和β″相析出过程得到促进,使得合金强度显著提高,T4合金屈服强度和抗拉强度分别为196 MPa和363 MPa,较无Zn合金分别提高30 MPa和44 MPa, T6合金屈服强度和抗拉强度分别为368 MPa和443 MPa,较无Zn合金分别提高44 MPa和57 MPa,同时,两种时效状态合金均能保持较高的延伸率;T4和T6合金显著增强的晶间腐蚀敏感性应与高Zn含量加大了晶界析出相与无析出区(PFZ)之间成分差异有关。此外,实验合金拉伸断口形貌特征基本不受Zn含量影响,而与时效状态密切相关:T4合金为韧窝型穿晶断裂,T6合金为沿晶断裂与韧窝型穿晶断裂共存模式。Due to the combination of low density,medium strength,high corrosion resistance,good weldability and plastic deform⁃ability,the Al-Mg-Si-Cu alloys had found wide applications in the field of automotive,rail transportation and aviation.However,the addition of Cu element could increase the strength of the alloys in peak-aging state but at the cost of corrosion resistance.In order to im⁃prove the strength and corrosion resistance simultaneously,the effects of Zn content on the tensile properties and intergranular corro⁃sion(IGC)susceptibility of Al-1.0Mg-0.95Si-0.9Cu-x Zn-0.6Mn-0.12Zr alloys(x=0,0.4,0.8,1.2)in the natural aging(T4)state for 14 d and peak aging(T6)state at 180℃for 8 h,were investigated by Vickers hardness test,tensile test,immersion corrosion test and differential scanning calorimetry(DSC),scanning electron microscopy(SEM),transmission electron microscopy(TEM).The re⁃sults showed that the addition of low Zn contents(0~0.8%)had no significant effect on the characteristic of hardness variation and ten⁃sile properties(strength and elongation)of T4 and T6 alloys.The yield strength,ultimate tensile strength and elongation of T4 alloys were in the range of 156~163 MPa,304~308 MPa and 27.5%~28.1%,respectively,and T6 alloys had the yield strength,ultimate tensile strength and elongation in the range of 336~340 MPa,395~404 MPa and 14.4%~14.8%,respectively.Furthermore,T4 alloys almost had no IGC susceptibility,whereas serious IGC occurred in T6 alloys,which decreased with the increase of Zn content.When Zn content of the alloy was 0.8%,the maximum corrosion depth was 320μm,which was 220μm less than that of Zn-free alloy.When Zn content of the alloy increased to 1.2%,the precipitation of Guinier Prestion zone(GP zone)andβ"phase was greatly promoted within the grains and caused significant improvement of age-hardening rate and the alloy strength.The yield strength and ultimate ten⁃sile strength of T4 alloy were 196 MPa and 363 MPa,respectively,which were increased by 30 MPa and 44 MPa compared w

关 键 词：AL-MG-SI-CU合金 Zn含量 拉伸性能 晶间腐蚀敏感性 

分 类 号：TG146.21[一般工业技术—材料科学与工程]