三維暫態模擬溫度場與應力場應用於 316L不銹鋼銲接分析之研究

Abstract

本研究利用有限元素軟體對不銹鋼板材316L 進行CO2 雷射銲接模擬 分析。模擬過程中，316L 不銹鋼的各種高溫物理參數以模擬軟體JMATPRO 分析結果所獲得，做為模擬分析的依據。本研究對板材進行銲接溫度場與 銲後應力應變場分佈的模擬分析，並考慮非線性材料特性進行熱-力結構耦 合分析過程。 溫度分析中，本研究採用67%的熱效率進行熱源模擬，銲接分析輸入 熱源的型式為高斯體熱源。使用獨立體熱源型式進行薄板材料三維模擬， 獲得的分析溫度與實驗結果僅有些許的誤差。角變形分析結果，經模擬分 析與銲接實驗發現，銲件在銲接冷卻後發生的角變形量相當小。橫向應力 分析中，因銲接熱源的高溫作用使得銲道附近有較高的溫度梯度，金屬板 材因銲接受熱而膨脹，但因遠離銲道材料的拘束，銲道附近形成壓縮應 力，也造成壓縮應變的發生。在銲接過程中，隨著熱源的消失，銲道從熔 融金屬開始凝固冷卻，此時體積產生收縮，於銲縫處存在一拉伸應力。當 板材溫度由高溫降至室溫時，體積仍持續收縮，造成銲縫處的拉伸應力向 上提升。縱向應力分析結果顯示，在銲道的起點與終點處皆有壓縮應力存 在，中間區則為拉伸應力。

This study simulated 316L stainless steel welding by ANSYS, and the welding method is CO2 laser welding. The high temperature physical properties of material are obtained by JMATPRO simulation for database establishment. The research is a simulation analysis of welding against temperature field and strain-stress field distribution. In that, nonlinear material characteristics within thermo -mechanical coupling process were considered. The 3D simulation of thin sheet metal used independent Gaussian cylinder heat source which possesses 67% thermo-efficiency. Then, one would find there exists little error between the temperature of experiment and the actual measurement. By welding experiment, it was discovered that the angular distortion of workpiece was quite small after welding. For horizontal stress analysis, high temperature of welding heat source results in a larger gradient along weld bead, where metal material expands. However, the region of surrounding metal with cold temperature restrains the expansion of welding bead, so the compressive stress and stain occur. Along with the decrease of temperature, fusing metal in weld bead starts to solidify and the volume of material shrinks continuously. Simultaneously, tensile stress increase in weld bead. For vertical stress analysis, that the compressive stress exists both ends of weld bead is contrary to the tensile stress occurs in the middle.