活性助銲劑對鎳基超合金Inconel 718銲道熔深能力之研究

Abstract

本研究之目的主要在探討活性助銲劑對鎳基超合金Inconel 718銲道熔深之影響。實驗材料選用鎳基超合金Inconel 718 (UNS N07718, AMS 5596-E)；活性助銲劑之選用以氧化劑為主，分別為SiO2、NiO、MoO3、Cr2O3、TiO2、MnO2、ZnO及MoS2共八種。銲接方法採用不加填料金屬，且以氬氣為保護氣體的鎢極惰氣銲(Tungsten Inert Gas, TIG)來進行Bead-on-Plate實驗。銲接過程中利用影像擷取系統(Charge-Coupled Device, CCD)記錄電弧動態影像及電弧電壓的變化；以金相實驗來觀察微觀組織；利用微硬度測定機來瞭解銲道機械性質；以實體顯微鏡來量測銲道形態，並記錄銲道熔深及寬度以計算深寬比。接下來根據所量測之深寬比，取最大值之前四種活性助銲劑，以各50%的比例來調配成六種混合型活性助銲劑，分別為SiO2-MoO3、SiO2-NiO、MoO3-NiO、SiO2-MoS2、MoS2-NiO、MoS2-MoO3，並探討混合型助銲劑對銲道熔深與深寬比之影響。實驗中發現在相同銲接參數下，不同之活性助銲劑，能有效提升鎳基超合金Inconel 718之銲道熔深達8%~63%；並提高深寬比達19%~125%。最後利用田口方法來進行最佳化實驗，以不同混合比例之SiO2與MoO3調製成混合型活性助銲劑，搭配主要之五種銲接製程參數，即銲接電流、銲槍走速、氬氣流量、鎢棒角度及電弧長度來最佳化銲接製程參數。運用田口方法所得之最佳參數，可使鎳基超合金Inconel 718銲道熔深提升135%；而深寬比提升284%。

The purpose of this study was to investigate the effect of activating fluxes to the welding penetration of nickel-base superalloy Inconel 718. Bead-on-plate argon TIG(Tungsten Inert Gas) welding process was made on Inconel 718 plate (UNS N07718, AMS 5596-E) without filling metals. The activating fluxes used in the experiment were SiO2, NiO, MoO3, Cr2O3, TiO2, MnO2, ZnO and MoS2. During the welding process, a charge-coupled device (CCD) was used to record the images of arc profile and voltage. Besides, the microstructure and morphology of the weldments were examined by the optical microscope. Furthermore, the Vickers hardness test was used to determine the mechanical properties of the weldments. According to the measurement results of the width and penetration of the weld bead, the depth to width ratio (D/W ratio) can be calculated. Based on the highest D/W ratio, four fluxes were selected to mix with each other using 50% weight percent each. The mixed fluxes were SiO2-MoO3, SiO2-NiO, MoO3-NiO, SiO2-MoS2, MoS2-NiO and MoS2-MoO3, and the mixed fluxes were used for investigating the effect to the welding penetration and D/W ratio. Under the same welding conditions, the results indicated that all fluxes did enhance the welding penetration of Inconel 718 by 8%~63%. Moreover, the D/W ratio was enhanced up to 125%. Finally, by employing the Taguchi Methods to achieve optimized welding penetration and D/W ratio, six major welding parameters were determined, which were welding current, torch moving speed, argon flow rate, vertex angle of electrode, arc length and the weight ratio of SiO2 and MoO3. The confirm experiment analysis of Taguchi Methods demonstrated that the welding penetration was enhanced 135%, and the D/W ration was also increased 284%.