Peng Hao, Zhao Yunlong, Fu Wanwan, Chen Zhishan, Zhang Man, Liu Jiesheng, Tan Xiaoming
School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan 430023, China.
Materials (Basel). 2024 Feb 23;17(5):1022. doi: 10.3390/ma17051022.
Hot stamping (or press hardening) is a new technology that is widely used in the production of advanced high-strength steel parts for automotive applications. Electrochemical measurements, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), and accelerated corrosion tests (the neutral salt spray test and periodic immersion test) were conducted on press-hardened samples produced from uncoated (cold-rolled and cold strip production (CSP) hot-rolled) and Al-Si-coated press-hardened steels to elucidate their distinct anti-corrosion mechanisms. The cross-sectional micromorphology and element distribution of three types of press-hardened steels after a neutral salt spray test were observed using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX). The corrosion resistance of Al-Si-coated press-hardened steel was found to be significantly diminished following the hot stamping process due to the presence of microcracks and elevated iron content in the coating subsequent to austenitizing heat treatment. On the other hand, the corrosion resistance of uncoated press-hardened sheets produced from cold-rolled and CSP hot-rolled press-hardened steel was found to be proximal due to their nearly identical composition and microstructure (fully martensite) after the hot stamping process. Considering the high efficiency and energy-saving properties of hot-rolled press-hardened steel, it holds the potential to replace cold-rolled and even aluminum-silicon-coated press-hardened steel in automobile manufacturing.
热冲压(或冲压硬化)是一项新技术,广泛应用于汽车用先进高强度钢部件的生产。对由未涂层(冷轧和冷轧带钢生产(CSP)热轧)和铝硅涂层冲压硬化钢制成的冲压硬化样品进行了电化学测量,包括动电位极化和电化学阻抗谱(EIS),以及加速腐蚀试验(中性盐雾试验和周期性浸泡试验),以阐明它们独特的防腐机制。使用扫描电子显微镜(SEM)和能量色散X射线分析(EDAX)观察了三种冲压硬化钢在中性盐雾试验后的横截面微观形态和元素分布。发现铝硅涂层冲压硬化钢在热冲压过程后耐腐蚀性显著降低,这是由于奥氏体化热处理后涂层中存在微裂纹且铁含量升高。另一方面,由冷轧和CSP热轧冲压硬化钢制成的未涂层冲压硬化板材在热冲压过程后由于其几乎相同的成分和微观结构(全马氏体),耐腐蚀性相近。考虑到热轧冲压硬化钢的高效节能特性,它在汽车制造中具有取代冷轧甚至铝硅涂层冲压硬化钢的潜力。