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  本文關(guān)鍵詞：擠壓態(tài)Mg-1Zn-2Y鎂合金高應變率變形行為　出處：《沈陽工業(yè)大學》2017年碩士論文　論文類型：學位論文

  更多相關(guān)文章： Mg-1Zn-2Y鎂合金 分離式霍普金森桿 高應變速率 動態(tài)力學性能 失效機制

【摘要】：鎂合金在地面交通、航空、航天等工程領(lǐng)域有著廣泛的應用,但目前針對鎂合金在高溫高應變率下動態(tài)壓縮力學行為的研究還不是很多,大多數(shù)的研究主要是針對高溫低應變速率條件。可是,在一些諸如廠房爆炸、爆恐襲擊、突發(fā)性火災等場合,金屬材料有可能受到高溫高應變率條件下的沖擊載荷,所以不同溫度下高應變率動態(tài)力學性能的研究極為重要。為此,本文采用分離式霍普金森壓桿對Mg-1Zn-2Y鎂合金的室溫及高溫高應變率力學行為,及其變形與失效機制進行了深入的研究。本文分別對溫度為室溫、100℃、150℃、200℃加載方向為ED和ERD的擠壓態(tài)Mg-1Zn-2Y鎂合金進行了高速沖擊壓縮試驗,應變率范圍為1290-3047s~（-1）;分別使用光學顯微鏡(OM)和掃描電鏡(SEM)對材料在變形前和變形后的金相組織進行了分析;使用χ-ray對合金的織構(gòu)進行分析;使用掃描電鏡(SEM)對沖擊試驗后的斷口進行分析。據(jù)此,探討了Mg-1Zn-2Y鎂合金的變形及斷裂機制。本文實驗結(jié)果表明:室溫時,Mg-1Zn-2Y鎂合金擠壓態(tài)試樣在ED及ERD方向都發(fā)生了屈服(ERD方向屈服點不明顯)。室溫時,ED方向試樣體現(xiàn)出正的應變率強化效應,ERD方向試樣只在1290-1552s~（-1）范圍內(nèi)為正的應變率強化效應,在1552-2602s~（-1）應力對應變速率的變化不敏感,沿ERD方向壓縮的應變率敏感性低于ED方向。相比而言,ED方向的屈服強度較ERD方向低,應變率強化效應比ERD方向更為顯著,斷裂強度較ERD試樣高,但其斷裂應變較ERD方向低。此外,ED方向真應力應變-曲線先下凹再上凸,ERD方向則沒有拐點,曲線上凸。高溫下Mg-1Zn-2Y鎂合金擠壓態(tài)試樣的屈服強度對應變速率的變化不敏感。相比而言,ED方向的塑性會更好一些,ED方向的沖擊吸收功大于ERD,表現(xiàn)出較為穩(wěn)定的應變率強化效應,但ERD方向的應變率強化效應和絕熱剪切敏感性大于ED方向。無論在室溫還是高溫下,Mg-1Zn-2Y鎂合金擠壓態(tài)試樣沿ED方向進行壓縮時的流變應力要高一些,這與織構(gòu)有關(guān),室溫及100℃時高應變率沖擊下的Mg-1Zn-2Y鎂合金的斷裂為韌脆共存的斷裂特征,為解理斷裂,不同加載方向解理斷裂程度不同。
[Abstract]:Aviation magnesium alloy on the ground, transportation, aerospace and other engineering fields are widely used, but for the magnesium alloy in high temperature and high strain rate on dynamic compressive mechanical behaviors are not much, most of the research is mainly aimed at high temperature and low strain rate conditions. However, in some areas such as plant explosion, explosion of terrorist attacks. The sudden fire and other occasions, metal materials are likely to be in high temperature and high strain rate impact load condition, so different temperature under high strain rate on the dynamic mechanical properties is very important. Therefore, this paper adopts the split Hopkinson pressure bar of Mg-1Zn-2Y magnesium alloy at room temperature and high temperature and high strain rate mechanical behavior and deformation mechanism. The failure is studied. Based on the temperature at room temperature, 100 degrees, 150 degrees, 200 degrees of high speed impact loading direction compression test for the extruded Mg-1Zn-2Y magnesium alloy ED and ERD, The strain rate range of 1290-3047s~ (-1) respectively; using optical microscope (OM) and scanning electron microscopy (SEM) on the microstructure of materials in deformation before and after deformation were analyzed using X -ray alloys; texture analysis; using scanning electron microscopy (SEM) on fracture impact test was analyzed. Accordingly, to investigate the deformation and fracture mechanism of Mg-1Zn-2Y magnesium alloy. The experimental results showed that at room temperature, the Mg-1Zn-2Y magnesium alloy extruded samples in ED and ERD direction (ERD direction happens to yield the yield point is not obvious). At room temperature, the ED sample shows the positive strain strengthening effect of ERD in the direction of the specimen only 1290-1552s~ (-1) in the range of positive strain strengthening effect in 1552-2602s~ (-1) is not sensitive to the change of stress and strain rate, compression along the ERD direction of the strain rate sensitivity is lower than that of ED direction. In contrast, the ED direction ERD direction is low yield strength, Strain rate than ERD direction is more significant strengthening effect, fracture strength is ERD samples of high, but its fracture strain is ERD direction ED direction is low. In addition, the stress-strain curve under the first concave to convex, ERD direction is no inflection point, convex curve is not sensitive. Mg-1Zn-2Y magnesium alloy extruded samples under high temperature the yield strength and strain rate changes. In contrast, the plastic will be better in the ED direction, ED direction of the impact absorbing energy is greater than ERD, showed a relatively stable strain rate strengthening effect, but the direction of the ERD strain rate strengthening effect and adiabatic shearing sensitivity of greater than ED. No matter at room temperature or high temperature state the sample along ED direction compression stress rheology to the high number of extruded Mg-1Zn-2Y magnesium alloy, and the texture of the high strain rate of fracture of Mg-1Zn-2Y magnesium alloy under the impact of room temperature and 100 DEG C for fracture characteristics of ductile brittle cleavage fracture for coexistence, The fracture degree of cleavage in different loading directions is different.

【學位授予單位】：沈陽工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG146.22

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