时效对铸造Al-Si-Cu-Mg合金力学性能和耐蚀性能的影响

Effect of aging on mechanical properties and corrosion resistance of Al-Si-Cu-Mg cast alloy

研究了单级、双级时效对铸造Al-Si-Cu-Mg合金显微组织、力学性能和耐腐蚀性能的影响。结果表明,铸造Al-Si-Cu-Mg合金时效后的显微组织主要由α-Al基体和共晶Si相构成。单级时效处理(170℃×10 h)后合金的峰值硬度为151.8 HV0.1,抗拉强度和屈服强度分别为287和252 MPa,伸长率为10.6%,但其耐腐蚀性能较差,最大晶间腐蚀深度达到113.3μm。与单级时效相比,双级时效(90℃×3 h+170℃×4 h)可显著改善铸造Al-Si-Cu-Mg合金的力学性能和耐腐蚀性能,其峰值硬度提高了5.7%,抗拉强度和屈服强度分别提高了4.5%和6%,伸长率提高了两倍以上。此外,合金的耐腐蚀性能也得到了改善,最大晶间腐蚀深度为60.0μm。合金获得较高力学性能和良好的耐腐蚀性能主要取决于均匀、细小的Si相,且灰黑色针状β相与黑色块状组织也相对较少。

Effect of aging treatment(single aging and two-step aging)on the microstructure,mechanical properties and corrosion resistance of Al-Si-Cu-Mg cast alloy was studied.The results show that the microstructure of the Al-Si-Cu-Mg cast alloy after aging is composed ofα-Al matrix and eutectic Si phase.After single aging at 170℃for 10 h,the peak hardness of the alloy is 151.8 HV0.1,the tensile strength and yield strength are 287 MPa and 252 MPa,respectively,and the elongation is 10.6%.However,the corrosion resistance is poor,and the maximum intergranular corrosion depth reaches 113.3μm.As compared with that after the single aging,after the optimized two-step aging at 90℃for 3 h and 170℃for 4 h,the mechanical properties and corrosion resistance of the tested alloy are greatly improved.The peak hardness is increased by 5.7%,and the tensile strength and yield strength are increased by 4.5%and 6%,respectively.Moreover,the elongation is increased more than twice.The corrosion resistance improves,and the maximum intergranular corrosion depth is reduced to 60.Oμm.The fine and uniform Si phase and relatively less gray-black acicularβphase and black block structure are responsible for the improvement of mechanical properties and corrosion resistance of the tested alloy.