7005與AZ61A拉伸、壓縮之機械性質研究; The mechanical properties of tensile and compression for 7005 aluminium alloy and AZ61A magnesium alloy

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Title:	7005與AZ61A拉伸、壓縮之機械性質研究;The mechanical properties of tensile and compression for 7005 aluminium alloy and AZ61A magnesium alloy
Authors:	郭光程;Guang-Cheng Kuo
Contributors:	機械工程研究所
Keywords:	動態回復;疊差能;7005;AZ61A;動態再結晶;stacking fault energy;7005;AZ61A;dynamic recovery
Date:	2001-07-18
Issue Date:	2009-09-21 11:36:26 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究主要探討應變速率及溫度對於六方緊密堆積結構之鎂合金AZ61A及面心立方結構的鋁合金7005之拉伸、壓縮機械性質和破斷面形態的影響。在拉伸測試方面，在低應變速率（1.85×10-4/s）及高應變速率（1.85×10-2/s）鎂合金AZ61A和鋁合金7005之抗拉強度、降伏強度均會隨著溫度上升而降低，而伸長率則是隨著溫度上升而增加。本研究發現，由於鋁合金是屬於疊差能較高的材料，當材料在低應變速率及高溫的測試條件下容易發生動態回復的現象，導致高溫時材料軟化。而鎂合金AZ61A在塑性變形過程中會形成本質型的疊差，使得鎂合金AZ61A在低應變速率及高溫的測試條件下，材料會發生動態再結晶的現象，導致材料高溫軟化。在壓縮測試方面，鎂合金AZ61A在低應變速率（1.85×10-4/s）時，其抗壓強度及降伏強度是隨著溫度上升而降低，而在高應變速率（1.85×10-2/s）則是呈相反的關係。鋁合金7005在低應變速率（1.85×10-4/s）時，其抗壓強度及降伏強度是隨著溫度上升而增加，當測試溫度超過100℃時則開始下降，而在高應變速率的機械性質則是呈現隨著溫度增加而下降。在破斷面的觀察方面，鎂合金AZ61A及鋁合金7005拉伸測試之破斷面形態都屬於延性破斷，而且當測試溫度愈高時，材料破斷面的凹洞愈大。而在壓縮測試方面，鎂合金AZ61A及鋁合金7005之破斷形態都屬於劈裂破斷形態，而且不受應變速率及溫度的影響。 This study investigated mainly about the effect of environmental temperature and strain rate on tensile, compression test and different morphology of fracture surface for two different materials: HCP structure — magnesium alloy, AZ61A and FCC structure — Aluminum alloy, 7005. Both materials were took tensile test at higher strain rate and lower strain rate and show the same trend that UTS, yield stress were decreased with increasing environmental temperature form room temperature to 300℃; elongation show oppositely trend of both materials. In this study, 7005 showed dynamic recovery while tensile tested under lower strain rate and higher environmental temperature due to its high stacking fault energy and under the same test parameters for AZ61A, magnesium alloy showed dynamic recrystallization and soften while tested at high environmental temperature due to intrinsic stacking fault during plastic deformation. For compression test of AZ61A, compression strength and yield stress decreased with increasing environmental temperature under lower compression strain rate; it showed oppositely trend under higher compression rate. For compression test of 7005, compression strength and yield stress decreased with increasing environmental temperature while over 100℃ under lower compression strain rate; compression strength and yield stress decreased with increasing environmental temperature under higher compression strain rate. For observation of morphology of fracture surface, both AZ61A and 7005 showed ductile rupture and the size of dimples on the fracture surface were enlarged with increasing environmental temperature. For compression test, both materials showed cleavage rupture regardless the strain rate and environmental temperature.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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