Cr、Si微量元素对钢/铝感应静压焊接接头组织及性能的影响

Cr,Si Trace Elements on Steel/Aluminium Induction Hydrostatic Welding Joint Organization and Properties of the Impact

为推进汽车车身的轻量化研究,对Q235与5052H32(1号)、40Cr与5052H32(2号)、Q235与6061-T6(3号)三组试样进行了感应静压焊接试验。结果表明:界面处生长的金属间化合物(IMC)主要包括近钢侧舌状Fe_(2)Al_(5)相和近铝侧针状FeAl_(3)相两种,Fe_(2)Al_(5)相的Gibbs自由能小于FeAl_(3)相,故界面处Fe_(2)Al_(5)相优先生长;1至3号试样Fe_(2)Al_(5)相平均厚度分别为20μm、14μm、11μm,对比1号和2号发现,40Cr钢中的Cr元素在界面处聚集并部分替换IMC中的Fe元素,降低Al在Fe中的扩散系数,抑制了Fe_(2)Al_(5)相的生成,因此2号试样中Fe_(2)Al_(5)相比1号试样薄6μm;对比1号和3号发现,6061-T6铝合金中Si元素参与界面反应,以固溶体的形式抑制了Fe_(2)Al_(5)相的生长,因此3号试样中Fe_(2)Al_(5)相比1号试样薄9μm;三种试样焊接头均为混合断裂,接头抗剪强度分别为31 MPa、68 MPa、73 MPa。

In order to promote the research on the automobile lightweighting,a induction-pressure welding method was used to join three groups of Fe/Al specimens for Q235&5052H32(No.1),40Cr&5052H32(No.2)and Q235&6061-T6(No.3).The results show that the intermetallic compounds(IMC)at the interface consists of the tongue-like Fe_(2)Al_(5)phase on the near-steel side and the needle-like FeAl_(3)phase on the near-aluminium side.The Gibbs free energy of the Fe_(2)Al_(5)is less than that of the FeAl_(3),leading to the preferentially growth for Fe_(2)Al_(5)at the interface.The average thicknesses of Fe_(2)Al_(5)for specimens 1 to 3 were 20μm,14μm and 11μm,respectively.Compared with No.1 and No.2,it was found that the Cr element in 40Cr steel gathered at the interface and partially replaced the Fe element in IMC,reducing the diffusion coefficient of Al in Fe and inhibiting the formation of Fe_(2)Al_(5),so that the thickness of Fe_(2)Al_(5)for No.2 is smaller than that of No.1 by 6μm.Compared with No.1 and No.3,it was found that the Si element in 6061-T6 aluminium alloy participated in the interfacial reaction and inhibited the growth of Fe_(2)Al_(5)in the form of solid solution,so that the thickness of Fe_(2)Al_(5)for No.3 is smaller than that of No.1 by 9μm.The fracture mode of these three specimens were all mixed and the shear strengths of Nos.1,2 and 3 were 31 MPa,68 MPa and 73 MPa respectively.