鍛造製程對AA6082鋁合金之顯微組織及機械性質研究

A Study of Forging Process on the Microstructure and Mechanical Properties of AA6082 Aluminum Alloy

張聖藝(S.Y. Chang) ； 張呈嘉(C.C. Chang) ； 何佳育(J.Y. Ho) ； 呂振益(C.Y. Lu) ； 廖學誠(H.C. Liao) ； 周棟勝(T.S. Chou)

《鑛冶：中國鑛冶工程學會會刊》 61卷4期 (2017/12) Pp. 77-88

https://doi.org/10.30069/MM.201712_61(4).0007

摘要

AA6082鋁合金經過熱變形（如擠型、鍛造、軋延…等）及熱處理之後，常會在其胚料表面形成晶粒粗大的再結晶層及粗細混晶現象，導致其機械性質與疲勞性質的劣化，因而影響鍛件之使用壽命。有鑑於此，本研究經由鍛造模流分析軟體進行連接座汽車底盤零件的三道次成形分析，並擷取胚料溫度場及等效應變變化，從中決定出影響粗晶生成的製程參數，接著以熱間壓扁製程探討其製程參數包括壓縮量、胚料溫度及模具溫度對熱處理後的顯微組織及機械性質之影響，並以模流分析進行溫度場及等效應變之比對。最後，利用DSC及EBSD試驗解析熱處理後粗細晶形成的原因。由研究結果顯示，粗晶區在熱處理前具有較強的立方位集合組織，(100) cube織構，與較高比例的高角度晶界的晶粒分佈型態。於熱處理後易造成異常粗晶的成長，藉此瞭解粗晶生成之主因及後續改善對策。

關鍵字

AA6082鋁合金 ； 鍛造 ； 顯微組織 ； 機械性質 ； 模擬分析

並列摘要

AA6082 aluminum alloy normally had a coarse-grained recrystallization layer and mixed grains on the surface of the workpiece after hot forming (extrusion, forging, rolling, etc.) and heat treatment. The recrystallization layer and mixed grains could degrade the mechanical and fatigue properties, thereby shorten the service life of the end products. We used Computer Aided Engineering (CAE) simulation to study the deformation behaviors of automobile chassis part via a three-step manufacturing process. We analyzed the simulation temperature field and effective strain data during the forming processes to clarify the effect of process parameters and mechanism for the growth of coarse grains. We identified the effect of the deformation ratio, material temperature, and mold temperature on the microstructure and mechanical properties of hot deformed and heat-treated samples. The EBSD revealed that deformed structure with a stronger (100) cube texture component associated with higher percentage of high-angle grain boundaries promoted the growth of coarse grains. With proper hot forming and heat treatment, the coarse grain was minimized to ensure the chassis products with the promised mechanical properties.

並列關鍵字

AA6082 Aluminum Alloy ； forging ； microstructure ； mechanical properties ； simulation analysis