| SHAO Rong,LI Min,LIU Yongzhuang,CAO Jianping,HAO Yulin,CAI Ning,LI Xuetao.Surface Analysis of Advanced High Strength Steel for Vehicle and Their Bonding Performance[J],53(4):211-219 |
| Surface Analysis of Advanced High Strength Steel for Vehicle and Their Bonding Performance |
| Received:December 22, 2022 Revised:May 06, 2023 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.04.020 |
| KeyWord:advanced high strength steel surface composition wettability bonding performance |
| Author | Institution |
| SHAO Rong |
Research Institute of Technology of Shougang Group Co., Ltd., Beijing , China;Beijing Key Laboratory of Green Recyclable Process for Iron & steel Production Technology, Beijing , China |
| LI Min |
Research Institute of Technology of Shougang Group Co., Ltd., Beijing , China;Beijing Key Laboratory of Green Recyclable Process for Iron & steel Production Technology, Beijing , China |
| LIU Yongzhuang |
Research Institute of Technology of Shougang Group Co., Ltd., Beijing , China;Beijing Key Laboratory of Green Recyclable Process for Iron & steel Production Technology, Beijing , China |
| CAO Jianping |
Research Institute of Technology of Shougang Group Co., Ltd., Beijing , China;Beijing Key Laboratory of Green Recyclable Process for Iron & steel Production Technology, Beijing , China |
| HAO Yulin |
Research Institute of Technology of Shougang Group Co., Ltd., Beijing , China;Beijing Key Laboratory of Green Recyclable Process for Iron & steel Production Technology, Beijing , China |
| CAI Ning |
Research Institute of Technology of Shougang Group Co., Ltd., Beijing , China;Beijing Key Laboratory of Green Recyclable Process for Iron & steel Production Technology, Beijing , China |
| LI Xuetao |
Research Institute of Technology of Shougang Group Co., Ltd., Beijing , China;Beijing Key Laboratory of Green Recyclable Process for Iron & steel Production Technology, Beijing , China |
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| Abstract: |
| To investigate the effect of oxide morphology, composition and content on bonding properties of advanced high strength steels for automotive applications. In this study, a white light interferometer, a scanning electron microscope (SEM) and a transmission electron microscope (TEM) were used to observe the surface morphologies of different high-strength steels (DH780, DP980, DP1180, CP1180). The microstructure and phase structure of high-strength steels were analyzed with a metallography microscope and an X-ray diffractometer (XRD). The variation of surface characteristic elements content with depth and the types of surface oxides were analyzed with a direct reading spectrometer, a glow spectrometer (GDS) and an X-ray photoelectron spectroscopy (XPS). The surface wettability of different high strength steels was compared by the contact angle test of different systems, and the surface free energy was calculated. Finally, the bonding properties of high-strength steel and three different automobile welding adhesives were tested, and the influence of surface composition of high-strength steel on bonding properties was analyzed and summarized. The results indicated that there were oxides enrichment on the surface of high strength steels. The morphologies, types and content of oxides on the surface of different high strength steels were different. The surface of DH780 was mainly composed of membrane-layered Al based oxides, while the surface of DP980, DP1180 and CP1180 was mainly composed of Si, Mn and Cr granular oxides. The surface oxides content of DP steels increased with the increase of strength. CP1180 steel had the lowest oxide content on the surface and the smallest oxides particle size. The results of contact angle test and calculations showed that DH780 had the worst surface wettability and the lowest free energy (29.2 mn.m–1). Compared with DP1180, the wettability and surface free energy of DP980 decreased slightly with the increase of the steel strength. CP1180 showed the best surface wettability and the highest surface free energy (40.5 mN.m–1). For the same kind of adhesive, DH780 showed the lowest shear strength and CP1180 showed the highest shear strength. In conclusion, the surface oxides enrichment of high strength steel has an important effect on surface wettability and surface free energy. The presence of Al based oxides on the surface of high strength steel significantly reduces the shear strength of the bonded joint. On the one hand, it is due to the decrease of surface free energy, which leads to the decrease of adhesion work. On the other hand, the main compositions of welding adhesive are epoxy resin and dicyandiamide curing agent. Oxides will prevent the polar groups such as epoxy and amino groups in the adhesive from forming strong interactions (covalent or ionic bonds) with the surface of the steel matrix, and more often form weakly interacting hydrogen bonds with oxides. Compared with Si, Mn and Cr, Al has the smallest diffusion activation energy in Fe, and it is easier for Al to diffuse to the steel surface at the same temperature. Moreover, the Al based oxides cover the entire surface of the high strength steel in a thin film. Thus, DH780 adhesive joint has the lowest shear strength and the worst bonding performance. |
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