(1. 重慶理工大學(xué) 材料科學(xué)與工程學(xué)院，重慶 400054；
2. 重慶大學(xué) 材料科學(xué)與工程學(xué)院，重慶 400044)
摘 要: 為了研究漸進(jìn)擴(kuò)徑成形(Progressive expanding forming, PEF)工藝對(duì)Al/Mg雙金屬?gòu)?fù)合方形管材成形過(guò)程多物理場(chǎng)及微觀組織的影響，根據(jù)PEF工藝的特點(diǎn)，采用DEFORM-3D軟件建立了三維熱力耦合的有限元數(shù)值模型并進(jìn)行模擬，在PEF工藝實(shí)驗(yàn)中開(kāi)展了微觀組織表征及硬度測(cè)試，研究了預(yù)熱溫度對(duì)成形載荷及坯料形變的影響、擠壓速度對(duì)坯料溫度場(chǎng)及等效應(yīng)力的影響，以及不同坯料預(yù)熱溫度對(duì)Al/Mg雙金屬微觀組織的影響。結(jié)果表明：PEF工藝可以產(chǎn)生大塑性變形(Severe plastic deformation)，有效地細(xì)化雙層方管的微觀組織，并且能夠直接一次形成壁厚為3 mm的Al/Mg雙金屬?gòu)?fù)合方管；坯料預(yù)熱溫度從340 ℃上升到430 ℃時(shí)，成形載荷呈下降趨勢(shì)，下降了約28.6%；擠壓速度越快，擠壓剪切擴(kuò)徑區(qū)的等效應(yīng)力越大；在Al/Mg雙金屬?gòu)?fù)合界面過(guò)渡區(qū)會(huì)形成Mg17Al12、MgAl、Mg2Al3三種鋁鎂的化合產(chǎn)物，結(jié)合層硬度較高；當(dāng)擠壓速度為10 mm/s、擠壓溫度為400 ℃、擴(kuò)徑角為150°時(shí)，方形管材Al/Mg結(jié)合層的缺陷較小，結(jié)合層的冶金結(jié)合效果理想，硬度約為138.14 HV。
關(guān)鍵字: 雙金屬；方形管材；數(shù)值模擬；漸進(jìn)擴(kuò)徑成形；微觀組織
（1. School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054, China;
2. School of Materials Science and Engineering, Chongqing University, Chongqing 400044, China）
Abstract:In order to study the influence of progressive expanding forming (PEF) process on the multi physical field and microstructure of Al/Mg bimetallic composite square tube in the forming process, a three-dimensional thermal mechanical coupling finite element numerical model was created using DEFORM-3D, and the simulation based on the features of the PEF process was carried out. The microstructure characterization and hardness test during PEF process experiment were performed. The effects of billet preheating temperature on forming load and blank deformation, the effects of extrusion speed on billet temperature field and effective stress, the effects of different billet preheating temperatures on Al/Mg bimetallic microstructure, and the bonding layer hardness distribution were investigated. The results reveal that the PEF process can cause severe plastic deformation(SPD), efficiently improve the microstructure of a double-layer square tube, and make an Al/Mg bimetallic composite square tube with a wall thickness of 3mm in a single step. When the preheating temperature of the billet rises from 340 ℃ to 430 ℃, the forming load decreases by 28.6%. The effective stress in the extrusion shear expanding zone increases as the extrusion speed increases. Three aluminum magnesium products of Mg17Al12, MgAl and Mg2Al3 will be generated in the transition zone of the Al/Mg bimetallic composite interface, and the bonding layer will have a high hardness. When the extrusion speed is 10 mm/s, the extrusion temperature is 400 ℃ and the expansion angle is 150°, the flaws of the Al/Mg bonding layer of square tube are minor, the metallurgical bonding effect of the bonding layer is excellent, and the hardness is around 138.14 HV.
Key words: bimetallic; composite square tube; numerical simulation; progressive expanding forming; microstructure
