AM350不鏽鋼箔片之微電漿銲接與熱處理研究

Abstract

本研究有兩大部分，第一部分是利用微電漿對厚度僅有0.076mm 之AM350 不鏽鋼箔片進行銲接，並求出AM350 箔片微電漿銲接製 程之最佳銲接參數，另外再搭配不同的銲前、銲後熱處理，可獲得 AM350 箔片銲件最佳熱處理條件。第二部分的研究則是進行AM350 波紋片之模擬試銲，並以銲接峰值電流為變數，以期求得最佳的 AM350 波紋片銲接參數。 研究結果顯示，當銲接峰值電流為2.5A，而銲接走速為7.5in/min時，可獲得最佳品質的AM350 不鏽鋼箔片銲件。另外，不論銲前熱 處理狀態為何，AM350 箔片銲件之機械性質主要取決於銲後熱處 理；若銲件未進行銲後熱處理，其拉伸強度呈現最低（僅約100MPa 左右），且熔融區內δ→γ的相變態會因為高達4.52 ×104 °C /sec 的冷卻速率，而具有Massive Transformation 的特性；若銲前及銲後皆施行SCT850 時效處理（455℃，持溫3 小時）之箔片銲件，其拉伸強度值最高（158MPa），但延伸率僅有2∼3%；當銲後時效溫度提升至535℃以上時，箔片銲件拉伸強度值會隨著之降低，但具有相當不錯的延伸率（約6∼8%）。 對於波紋片銲件的研究成果，當銲接峰值電流設定在4A~5A 間時，具有圓弧狀的銲道外觀，可獲得最佳的銲接品質。

This investigation included two major parts. The first was to develop the optimal welding parameters and heat treatment conditions for AM350 stainless steel foil welds with a thickness of 0.076mm. The second was to simulate the plasma arc welding process and establish the appropriate welding parameters for AM350 bellow weldments. Results of this investigation revealed that AM350 foil welds would have the optimum qualities as the peak current and welding speed were fixed at 2.5A and 7.5in/min respectively. The tensile properties of foil specimens, regardless of their former heat treatment conditions, were determined by the post-heat treatment. The foil weldments without post-heat treatment had the minimum tensile strength, only 100MPa, and the solid-state phase transformation of δ→γwas found to be via massive transformation due to its extremely high cooling rate of 4.52 ×104 °C /sec . The foil specimens subjected to the SCT850 heattreatment before and after welding performed the highest tensile strength of 158MPa, but with a quite low elongation. The elongation of the foil welds would be substantially increased as the aging temperature was raised to 535℃. For bellow welds, while the peak current was set between 4A and 5A, the shape of the weld pool would appear a continuous circular, which could homogeneously distribute the stress on the welds.