低碳鋼與不□鋼異種材料MIG-Flux 接合製程參數最佳化之研究

Abstract

本研究目的主要在探討助銲劑添加對異種材料銲道熔透深度與機械性質之影響。銲接方式採用不開槽對接，且以氬氣為保護氣體的惰性氣體金屬極電弧銲接法來進行Butt joint實驗。實驗材料選用SAE 1020低碳鋼及AISI 304不□鋼，活性助銲劑之選用以氧化劑為主，分別為MnO2、MgCO3、Cr2O3、MoS2、NiO、MoO3、MgO、Fe2O3、ZnO、SiO2及TiO2共十一種。實驗中發現，當採用銲接速度346 mm/min及銲接電壓23.3 V組合時，將可得到較佳的銲件機械性質。其中添加MnO2單一型助銲劑時，可提升銲道深寬比及降低銲道中肥粒鐵含量，當添加MoS2-MoO3混合型助銲劑時，可提高銲道熔深及熔融面積，對於銲道中肥粒鐵含量及銲道微硬度表現皆有極佳效果。最後利用田口方法，以不同混合比例之MoS2與MoO3調製成混合型助銲劑，搭配銲接電壓、氬氣流量、銲接速度針對銲接製程進行最佳化實驗。經田口方法可得，當製程參數設定值為銲接電壓21.4 V、氬氣流量8 l/min、銲接速度403 mm/min且混合型助銲劑粉末比例為20%MoS2+80%MoO3時，為SAE 1020低碳鋼與AISI 304不□鋼之MIG-Flux接合之最佳參數。透過變異數分析(ANOVA)可知，影響銲道深寬比的重要參數，依序為銲接電壓、混合型助銲劑粉末比例、銲接速度、氬氣流量。

The purpose of this research is to study the effect of adding several fluxes on the weld penetration and mechanical properties of SAE 1020 low-carbon steel and AISI 304 stainless steel. Butt joint argon MIG(Metal Inert Gas) welding process was made on low-carbon steel SAE 1020 and stainless steel AISI 304 plate. The activating fluxes used in the experiment were MnO2, MgCO3, Cr2O3, MoS2, NiO, MoO3, MgO, Fe2O3, ZnO, SiO2 and TiO2. The experiment found that when using torch moving speed of 346 mm/min and welding voltage of 23.3 V, it will be better mechanical properties. The flux MnO2 is the best of all fluxes according to the weld depth/width ratio(D/W ratio) and reduce the weld FN(ferrite content). The mixed fluxes MoS2-MoO3 can enhance the welding penetration and fusion zone, and it can improve the mechanical properties of the weld micro-hardness and FN. Finally, by employing the Taguchi Methods to achieve optimized welding penetration and the D/W ratio, which were welding voltages, argon flow rate, welding torch travel speed and the weight ratio of MoS2 and MoO3. From the results of Taguchi Methods experiment, the optimal welding parameters for joining of the SAE 1020 carbon steel and the AISI 304 austenitic stainless steel are (1) welding voltages of 21.4 V; (2) argon flow rate of 8 l/min; (3) welding torch travel speed of 403 mm/min; and (4) mixed powder combination of 20% MoS2 and 80% MoO3. Beside, from the results of analysis of variance (ANOVA), the orders of the importance on the D/W ratio of weld pool geometry within the four control factors are (1) welding voltages; (2) mixed powder; (3) welding torch travel speed; and (4) argon flow rate.