【摘要】：5xxx系鋁合金具有較高的比強度和較好的成形性能,成為汽車輕量化材料的首選。合金的成形性能與塑性各向異性密切相關,而塑性各向異性從本質上又決定于晶體學織構。為了進一步提高合金的使用性能,更好的滿足汽車輕量化的需求,本文在商用5182鋁合金的基礎上,進一步提高合金中的Mg含量,控制其它合金元素的含量,優(yōu)化軋制及退火工藝,同時改善了合金的力學性能和成形性能。本文系統(tǒng)研究了Mg、Cu、Zn合金元素以及軋制和再結晶退火工藝對合金組織性能及織構的影響。同時針對室溫變形時A1-Mg合金中的鋸齒屈服效應,詳細分析了合金成分、加工參數(shù)、加載應變速率等條件對鋸齒屈服效應的影響,并結合動態(tài)應變時效微觀機制,對上述現(xiàn)象進行了解釋。得到了以下結論： 獲得了一種高強度易成形的5xxx系鋁合金,其成分如下：Al-6.1Mg-0.15Cu-0.2Mn-0.1Si-0.2Fe-0.05Cr(wt%),該合金經(jīng)兩次冷軋、中間退火及450℃/1h再結晶退火后,與商用5182鋁合金相比,在保持合金成形性能基本不變的前提下,大幅度提高了合金的力學性能。 合金的成形性能隨Mg和Cu含量的增加均呈現(xiàn)“∧”型變化。合金元素含量沒有改變合金的織構組分,但對織構密度及其體積分數(shù)產生了較大影響。粒子激發(fā)形核作用大大降低了合金的織構密度,再結晶退火后的合金通過應變誘導晶界遷移機制保留了部分軋制織構取向,提高了合金的成形性能。隨最終冷軋壓下率的增加,合金的成形性能下降,較高的中間退火溫度和再結晶退火溫度有利于提高合金的成形性能。 合金在較寬的加載應變速率范圍內都具有鋸齒屈服效應。隨著應變速率的減小,拉伸曲線上的鋸齒越來越強烈,高Mg合金呈現(xiàn)從A類到B類再到C類鋸齒的轉變,并且出現(xiàn)臨界應變。應力跌幅和再加載時間隨應變和Mg含量的增加而增大,并且其增大的速率也隨固溶Mg原子濃度的增加而增大。退火態(tài)的合金中,應力跌幅和再加載時間隨晶粒尺寸的增大而減�。豪滠垜B(tài)的合金由于具有較高的晶界和位錯密度,其鋸齒屈服效應最為強烈。
[Abstract]:5xxx aluminum alloy has high specific strength and good formability, so it is the first choice of automotive lightweight materials. The formability of alloys is closely related to plastic anisotropy, which is essentially determined by crystallographic texture. In order to further improve the performance of the alloy and better meet the requirement of automobile lightweight, this paper, on the basis of commercial 5182 aluminum alloy, further increases the content of Mg in the alloy and controls the content of other alloy elements. The rolling and annealing processes were optimized and the mechanical properties and formability of the alloy were improved. The effects of elements of Mg,Cu,Zn alloy, rolling and recrystallization annealing on the microstructure and texture of the alloy have been studied systematically in this paper. Aiming at the sawtooth yield effect of A1-Mg alloy during room temperature deformation, the effects of alloy composition, processing parameters and strain rate loading on the sawtooth yield effect are analyzed in detail, and the dynamic strain aging microcosmic mechanism is combined. The above phenomena are explained. The following conclusions are obtained: a kind of 5xxx aluminum alloy with high strength and easy forming has been obtained. The composition of the alloy is as follows: Al-6.1Mg-0.15Cu-0.2Mn-0.1Si-0.2Fe-0.05Cr (wt%), which has been cold-rolled twice. After intermediate annealing and recrystallization annealing at 450 鈩，

本文編號：2375552