文章信息/Info

Title:

The Dynamic Property and Microstructure Evolution of Extruded 6061 Aluminum Alloy

作者:

李落星1; 2; 葉 拓1; 2; 郭鵬程1; 2; 徐從昌1; 2

(1. 湖南大學(xué)汽車車身先進設(shè)計制造國家重點實驗室
(2. 湖南大學(xué)機械與運載工程學(xué)院

Author(s):

LI Luoxing1; 2;  YE Tuo1; 2;  GUO Pengcheng1; 2;  XU Congchang1; 2

 1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University
(2. College of Mechanical and Vehicle Engineering, Hunan University

關(guān)鍵詞:

熱處理; 鋁合金; 微觀組織; 動態(tài)力學(xué)性能

DOI:

10.7502/j.issn.1674-3962.2016.04.04

文獻標(biāo)志碼:

A

摘要:

采用分離式霍普金森壓桿(SHPB)，在應(yīng)變速率為2000 s-1和5500 s-1條件下，對不同熱處理狀態(tài)下的6061鋁合金擠壓試樣進行動態(tài)壓縮實驗。采用維氏硬度(HV)、光學(xué)顯微鏡(OM)和透射電鏡(TEM)對微觀結(jié)構(gòu)演變進行研究。實驗結(jié)果表明：隨著固溶溫度增加，材料的動態(tài)力學(xué)性能不斷增加，當(dāng)固溶溫度達到535 ℃達到穩(wěn)定，此時基體中的二次相粒子基本溶解，同時未見發(fā)現(xiàn)晶粒尺寸明顯長大現(xiàn)象。由于溶質(zhì)原子溶入基體形成置換式固溶體，金屬的晶體點陣發(fā)生畸變，固溶合金在高速沖擊下，位錯運動受到阻礙，位錯密度增加，并有位錯墻形成。將535 ℃/1 h固溶后材料在180 ℃條件下進行人工時效，6061鋁合金的動態(tài)流變應(yīng)力隨著時效時間增加，當(dāng)人工時效時間為8 h時，合金動態(tài)力學(xué)性能達峰值。時效初期形成了大量GP區(qū)，隨著時效時間增加，GP區(qū)向β″轉(zhuǎn)變，β″強化相的密度不斷增加，并在8 h達到峰值。在高速沖擊過程中，析出相有顯著的釘扎作用，阻礙了位錯的運動，導(dǎo)致大量的位錯堆積，形成大量位錯墻和位錯胞。

Abstract:

The dynamic mechanical properties of extruded 6061 aluminum alloy under different heat treatment conditions were investigated by split Hopkinson pressure bar (SHPB). The compression strain rates were 2000 s-1 and 5500 s-1. Vickers hardness, optical microscopy (OM) and transmission electron microscopy (TEM) have been used to study the microstructure evolution. The results show that the dynamic stress of extruded 6061 aluminum alloy increases with increasing solution temperature until the temperature reaches 535 ℃. Most of the phases have dissolved in the matrix, and the grain size has no obvious change. During dynamic deformation, the motion of the dislocations was impeded due to the lattice distortion, and the dislocation walls were found. The solution treated 6061 aluminum alloy was aging treated at 180℃. The dynamic stress increases with aging time. The peak stress of the alloy was obtained when the aging time was 8 h. At the beginning of artificial aging, a number of GP zones are formed. As the aging time increasing, the GP zones transform to β″. The density of strengthening precipitation reaches the peak when the aging time was 8 h. The pinning effect of the precipitation on the dislocation during dynamic deformation, results in the pile-up of dislocation, and forms a large number of dislocation walls and dislocation cells.