本文選題：壓鑄鋁合金 + 壓鑄工藝　； 參考：《東南大學》2017年碩士論文

【摘要】：隨著汽車輕量化的快速發(fā)展,壓鑄技術(shù)及高強韌壓鑄鋁合金在汽車關(guān)鍵零部件上的應(yīng)用一直是壓鑄領(lǐng)域研發(fā)的熱點之一。本文系統(tǒng)了研究壓鑄過程中工藝參數(shù)對試樣性能的影響,以及組織變化、缺陷控制對試樣性能的影響,同時探討了壓鑄合金在熱處理過程中組織和性能變化規(guī)律,對壓鑄鋁合金生產(chǎn),提高產(chǎn)品質(zhì)量具有重要的理論及實際意義。結(jié)合壓力鑄造的特點,本論文研究了在高壓鑄造下工藝參數(shù)對鋁合金鑄件的組織特征、力學性能和缺陷控制的影響。實驗采用了正交試驗設(shè)計和分析方法,通過優(yōu)化壓鑄工藝實驗參數(shù):澆注溫度、高速切換點位置和壓射速度,探討了不同壓鑄工藝條件下ADC12合金顯微組織和力學性能的關(guān)系。研究結(jié)果表明:鑄件的綜合力學性能受澆注溫度影響最大,臨界壓射速度、高低速切換點位置次之。當澆注溫度為680 ℃,快壓射臨界速度為3.0 m/s,高速切換點位置440 mm時,鑄件中顯微組織α-Al枝晶細小且分布均勻,微孔缺陷較少,合金密度達到最大值2.73 g/cm3,其綜合力學性能最好,其最大抗拉強度達到235.5 MPa,斷后延伸率2.8%,高于標準鑄態(tài)ADC12鋁合金的力學性能。從拉伸試樣的宏觀端口分析得到,試樣斷裂機制是脆性斷裂。為進一步控制壓鑄件內(nèi)部孔洞缺陷,來提升其力學性能,本文采用超低速慢壓射工藝,考慮到壓鑄機、壓鑄模具與壓鑄合金的有機結(jié)合,改用AC4CH合金能較好的匹配本實驗用的壓鑄機的技術(shù)參數(shù)與壓鑄模具,得到的壓鑄件壓鑄缺陷更少、性能更高,在此基礎(chǔ)上從熔體凈化處理和優(yōu)化壓射速度工藝參數(shù)兩個方面分析AC4CH合金的顯微組織、力學性能和缺陷控制的關(guān)系。結(jié)果表明,當精煉劑添加量為0.3 wt%,靜置時間30 min,鋁熔體獲得較佳的精煉凈化效果,鋁熔體含氫量控制在0.30 ml/100 g以下;再通過工藝的優(yōu)化,當慢壓射臨界速度為0.18 m/s時,壓鑄件中微觀組織枝晶α-Al相對細小致密,孔洞缺陷明顯減小,合金密度達到最高,鑄態(tài)下其綜合性能達到最大,即抗拉強度、斷后延伸率分別達到 267.5 MPa、15.4%。對超低速慢壓射的壓鑄鋁合金AC4CH進行了固溶和時效工藝的優(yōu)化,以進一步提高合金的力學性能。實驗結(jié)果表明,采用低溫固溶和時效工藝(510 ℃×6 h+170℃×3 h),合金的抗拉強度和延伸率可分別達到334.7MPa和9.5%,同時大幅度地減少了鑄件表面"起泡"缺陷,降低了產(chǎn)品的廢品率。
[Abstract]:With the rapid development of automobile lightweight, the application of die casting technology and high strength and toughness die casting aluminum alloy in automobile key parts has been one of the hot spots in the field of die casting. In this paper, the influence of the process parameters on the properties of the samples during die casting, the change of the microstructure and the effect of the defect control on the properties of the specimens are studied systematically. The changing rules of the microstructure and properties of the die casting alloys during the heat treatment are also discussed. It has important theoretical and practical significance for die-casting aluminum alloy production and improving product quality. Combined with the characteristics of pressure casting, the effect of process parameters on the microstructure, mechanical properties and defect control of aluminum alloy castings under high pressure casting was studied in this paper. The orthogonal experimental design and analysis method were adopted. The relationship between microstructure and mechanical properties of ADC12 alloy under different die casting conditions was discussed by optimizing the parameters of die casting process, such as pouring temperature, position of high speed switching point and injection speed. The results show that the comprehensive mechanical properties of the castings are most affected by the pouring temperature, the critical injection speed and the position of the high and low speed switching point are the second. When the casting temperature is 680 鈩，

本文編號：1842819