使用Cu-6Sn填料真空硬銲三種基材之研究

Abstract

本實驗使用Cu-6Sn填料合金，來分別真空硬銲接合鎳基(Inconel 600)、鐵鎳基(Incoloy 800)、鐵基(316L Stainless Steel)三種基材合金，Cu-6Sn填料比起傳統接合製程常使用的Cu箔填料，擁有較高的抗腐蝕性能和機械性能，由於Sn的添加，熔點大幅降低使製程溫度下降，亦可達節省能源之效益。藉由調整硬銲製程中的硬銲溫度、持溫時間等參數來進行接合，透過掃描式電子顯微鏡觀察接合後的銲道顯微結構與析出物分布狀況，並進行EPMA成分定量分析。再將部分試片進行剪力測試，觀察破壞表面形貌和斷裂橫截面來探討顯微組織與剪力強度的關係。 實驗結果顯示Inconel 600基材接合後，銲道兩側形成Cr3C2碳化析出物，破斷面主要為滑移方式所造成的韌性破壞形貌，在硬銲條件1080°C持溫10分鐘時有最大剪力強度353±21 MPa；Incoloy 800基材接合後，銲道內並無析出物形成，由於填料中的Cu與Fe不互溶，因此可觀察到填料原子沿晶界擴散的滲透現象，破斷面為準劈裂破壞，在硬銲條件1080°C持溫10分鐘時有最大剪力強度296±25 MPa；316L不鏽鋼基材接合後，銲道介面出現固態反應所形成的擴散層，溫度升高至1080°C後，破斷面韌性特徵大幅增加，在硬銲條件1100℃持溫10分鐘時有最大剪力強度397±51 MPa。

In this research, Cu-6Sn filler metal is applied in the vacuum brazing of three substrates, Nickel-based alloy (Inconel 600), Iron-Nickel-based alloy (Incoloy 800) and Ferrous alloy (316L Stainless steel) respectively. The corrosion resistance and the mechanical properties of Cu-6Sn filler metals are much superior to those of the copper foils often utilized in traditional brazing. The reduction of melting temperature due to the addition of tin decreases the brazing temperature, which achieves economizing on heat energy as well. Brazing was performed by controlling parameters such as brazing temperature and holding time. The microstructure of brazed joints and the distribution of precipitates were observed by SEM after vacuum brazing, followed by the EPMA quantitative chemical analysis. Furthermore, selected brazed specimens were conducted in shear test. The relationship between microstructure and shear strength were discussed by means of the images of fractured surface and cross section. The experimental results show as follows. For IN-600/Cu6Sn/IN-600 brazed joint, the interface of brazing area contains Cr3C2 carbide precipitates. Its fractograph is dominated by ductile dimple fracture with sliding marks. The specimen brazed at 1080°C for 10 minutes demonstrates the best shear strength of 353±21 MPa. For IN-800/Cu6Sn/IN-800 brazed joint, there are no precipitates formed in brazing area. Grain boundary penetration of molten filler metals in IN-800 substrate is observed as a result of the insolubility between copper and iron. The specimen brazed at 1080°C for 10 minutes demonstrates the best shear strength of 296±25 MPa. For 316L/Cu6Sn/316L brazed joint, diffusion layers are formed by solid state diffusion at 316L/Cu6Sn interface. The characteristics of dimple are much evident in fractured surface as brazing temperature rises above 1080°C. The specimen brazed at 1100°C for 10 minutes demonstrates the best shear strength of 296±25 MPa.