銲後熱處理對鍛/擠製時效鈦合金銲件之顯微組織與機械性質研究

Abstract

本研究目的主要係探討鍛造與擠製鈦合金進行銲前固溶時效熱處理與銲後應力消除及固溶時效處理對機械性質之影響。實驗材料選用目前業界普遍使用的Ti-6Al-4V合金，進行一系列的機械性質與顯微組織分析。銲接方法採用TIG自動銲接設備，並以氬氣氣氛保護，將時效後鍛造材與鍛造材、鍛造材與擠製材及擠製材與擠製材分別進行多層次的TIG對銲。 實驗結果顯示，鈦合金經過銲後固溶時效處理可以獲得最佳的抗拉強度；鍛造材約增加21.73％及擠製材約增加24.89％；延伸率卻遽降至最小值；鍛造材約降低85.27％及擠製材約降低79.05％。然而，銲後僅施以應力消除之抗拉強度(鍛造材1026.85MPa；擠製材946.59MPa)與延伸率(鍛造材8.71％；擠製材6.71％)仍可以維持與銲後不施以任何熱處理的抗拉強度(鍛造材1007.86MPa；擠製材935.78MPa)及延伸率(鍛造材8.76％；擠製材8.45％)的水準，可得到較佳的加工條件。另鍛/擠銲件試片在TIG銲前與銲後無論是否有施以熱處理，拉伸試驗的過程中，斷裂皆位於擠製件一邊，其顯示鈦合金擠製件有較低的強度。另鈦合金鍛造材與擠製材執行對接銲的抗拉強度較同種材質銲接時為低，顯示鈦合金構件必須進行異質材料銲接時，工程設計之抗拉強度值應慎重評估。

本實驗研究的貢獻為當鈦合金執行多層次TIG銲後，為得到較好的抗拉強度與延伸率時，採用應力消除，可以維持較適當的機械性質。因為銲後固溶時效處理雖可以得到最高的抗拉強度，但延伸性卻變的很差，且銲件有偏向脆性的現象。

This research goal is mainly discusses forging/ extrusion titanium alloy carries on welds melts the aging heat treatment after welding stress relieving and the melting aging treatment of metal to influence of the mechanical property. The experiment material selects the present field universal use the Ti-6Al-4V alloy, carries on a series of mechanical properties and the Microstructure analyzes. The welding method uses the TIG automatic welding equipment, and by argon atmosphere protection, after the aging, forges the material and the forging material, the forging material with extrusion material and extrusion material with to extrusion material to carry on the multi-level TIG butt welding separately. The experimental result showed that titanium alloy after the over weld melts the aging treatment of metal to be possible to obtain the best tensile strength; The forging material approximately increases 21.73% and extrusion material approximately to increase 24.89%; The elongation ratio actually suddenly drops to the minimum value; The forging material approximately reduces 85.27% and extrusion material approximately to reduce 79.05%. However, after welding, only serves with tensile strength of the stress relieving (forging material 1026.85MPa, extrusion material 946.59MPa) with the elongation ratio (forging material 8.71%, extrusion material 6.71%) still might maintain after welding does not serve with any heat treatment the tensile strength (forging material 1007.86MPa, extrusion material 935.78MPa) and the elongation ratio (forging material 8.76%, extrusion material 8.45%) the standard, may obtain the good working condition. Another titanium alloy forging material with extrusion material carries out when the butt welding tensile strength homogeneous material quality welding to lowly, demonstrated when the titanium alloy component must carry on the neterogeny material welding, tensile strength of value the engineering design should appraise prudently. This experimental study contribution, when the titanium alloy carries out multi-level TIG weld, to obtain time the good tensile strength and the elongation ratio, uses stress relieving, may maintain the suitable mechanical property. Because after welding, although melts the aging treatment of metal to be possible to obtain the highest tensile strength, but the extensibility actually changes is very bad, and the weldment has the deviation brittle phenomenon.