Ni-Cr-Mo 저합금강에 Ta 합금이 폭발압접된 클래드 계면의 미세조직 및 기계적 특성 고찰

• Published in: 대한금속·재료학회지, 62(11) Vol. 62; no. 11; pp. 857 - 867
• Main Authors: 김시연, Si-yeon Kim, 김태경, Tae-gyeong Kim, 장성진, Sung-jin Chang, 김동훈, Dong-hoon Kim, 양성호, Sung-ho Yang, 홍현욱, Hyun-uk Hong
• Format: Journal Article
• Language: Korean
• Published: 대한금속재료학회 01.11.2024; 대한금속·재료학회
• Subjects: explosive welding; interface; microstructure; tantalum alloy; tensile test; 재료공학
• ISSN: 1738-8228; 2288-8241
• DOI: 10.3365/KJMM.2024.62.11.857

The effects of welding variables (stand-off distance and explosive thickness) on the interfacial microstructure evolution and mechanical properties of explosively welded Ta alloy to Ni-Cr-Mo low alloyed steel have been investigated. Regardless of welding conditions (a stand-off distance of 3-5 mm and explosive thickness of 40-80 mm), the Ta/steel interface consistently exhibited a wavy configuration. This wavy interface facilitated the formation of vortex, resulting in strong interlocking. The height of the vortex increased with a larger stand-off distance at a fixed explosive thickness of 60 mm. Similarly, increasing the explosive thickness at a stand-off distance of 3 mm also resulted in a greater vortex height. The explosive weldability window, plotting the collision angle (β) against the collision point velocity (v c ), was successfully established for the dissimilar Ta and steel plates. The upper limit prediction with N=0.11, as proposed by Wittman, best matched the experimental results. This guided the determination of the optimal condition, which was a standoff distance of 3 mm and an explosive thickness of 40 mm. A vortex melted zone (VMZ) was identified, which resulted from the dynamic intermixing of Ta and steel, combined with localized melting caused by high-energy collisions and heat accumulation. The VMZ surrounded by a highly deformed Ta alloy, showed the highest hardness. Near the interface on the steel side, a fine recrystallized grain structure was observed. No significant inter-diffusion was detected at the wavy Ta/steel interface. The tension-shear properties of the wavy interface, which was subjected to loading parallel to interface, showed a good balance of strength and ductility, confirming the soundness of Ta/steel interface.