16Crステンレス鋼とアルミニウムとの圧延クラッド材の熱処理によるピール強度変化と強度発現機構

• Published in: 鉄と鋼 Vol. 105; no. 4; pp. 462 - 470
• Main Authors: 奥井, 利行, 潮田, 浩作
• Format: Journal Article
• Language: Japanese
• Published: 一般社団法人 日本鉄鋼協会 2019
• Subjects: aluminum; bonding strength; clad sheet; interfacial structure; peel strength; roll bonding; stainless steel
• ISSN: 0021-1575; 1883-2954
• DOI: 10.2355/tetsutohagane.TETSU-2018-133

The peel strength of 16Cr-ferritic stainless steel / aluminum rolled clad sheet is improved by heat treatment at 300 to 500 °C after clad rolling. The joint mechanism was studied by analyzing the fracture surface after the peel test, taking into account the characteristics of the peel test method.The detailed investigation into the fracture surface after peel test allows us to classify fracture sites into three categories: 1) ductile fracture in aluminum base material, 2) flake-like fracture in 16Cr-stainless steel, and 3) fracture in the intermediate interface layer between aluminum and 16Cr-stainless steel. It was revealed that the intermediate layer breakage mainly occurs in the as-rolled clad sheet; whereas after heat treatment at 300 to 500°C, the aluminum base material breakage predominantly occurs.Close observation into the state of deformation at the crack tip of the peel tested specimen leads us to conclude that clad rolled and subsequently annealed aluminum undergoes plastic deformation during the peel test because significant softening easily takes place preferentially in aluminum during low temperature heat treatment. This might imply the decrease in peel strength by heat treatment, which is different from the fact. However, the load area responsible for peeling force during the peel test is inferred to substantially increase, which gives rise to the increase in peel strength. This is because the peel strength is simply evaluated by dividing the peel force by the width of the specimen.