A novel traditional technique: Study on microstructure and performance of copper inlay decorative treatment on steel blades

Abstract

In the generational inheritance of traditional crafts, a great deal of important technique information is not directly recorded in literature or archaeological materials. This study analyzes the traditional copper inlay technique used on Longquan Blades, including the inlaying of pure copper and brass on both sides of the steel blade. The main findings of this study are presented as follows based on the use of OM, SEM, EDS, microhardness testing, and electrochemical measurements: (1) Copper is inlaid through a solid-liquid-solid phase transition, successfully bonding the copper decoration with the steel blade matrix, thereby forming a stable inlay interface, demonstrating the feasibility of the liquid copper inlay technique for metal ware decoration. However, the metallurgical bond was not formed at the interface. (2) Hardness test results show that the surface hardness of the steel blade matrix (167.5∼206.3 HV) > copper/steel bonding interface (152.3∼183.9 HV) > copper decoration zone (76.4∼91.9 HV). This hardness gradient is likely to exacerbate stress concentration at the bonding interface. (3) Further electrochemical analysis reveals that the corrosion resistance of the samples follows the order: L01-A < L02-A < L01-C < L02-B < L01-B. This indicates that the composite material interface with inlaid copper has a greater corrosion tendency than single materials. Additionally, the corrosion rate at the bonding interface of brass-inlay samples is lower than that of pure copper-inlay samples. Therefore, this study provides a practical method for reconstructing endangered craftsmanship and technical pathways, underscoring the broader significance of this study.