本文關鍵詞：擠壓—剪切變形鎂合金的摩擦磨損行為及機理研究　出處：《重慶理工大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 擠壓-剪切 顯微組織 變形鎂合金 磨損機制 有限元分析

【摘要】：鎂合金擠壓-剪切工藝(Extrusion-Shear,簡稱ES)是課題組開發(fā)的一種結合了正擠壓和等徑角擠壓的新型塑性變形技術。研究表明該工藝能夠有效細化鎂合金晶粒,提高鎂合金力學性能,但對鎂合金摩擦磨損性能的影響尚未研究。本文在研究ES變形鎂合金微觀組織和力學性能的基礎上,通過往復摩擦試驗,結合數(shù)值模擬對ES變形鎂合金的摩擦磨損性能進行了深入研究。對不同塑性變形方式(擠壓-剪切、正擠壓)、不同ES變形溫度和模具轉角及不同坯料原始狀態(tài)下制備的變形鎂合金進行了XRD、金相組織觀察和顯微硬度測試實驗及分析。結果表明:與正擠壓相比,擠壓-剪切變形中模具轉角的兩次剪切作用使AZ系鎂合金微觀組織更細化均勻;變形溫度為370℃時,ES變形AZ31鎂合金晶粒細小,變形溫度為400℃和420℃時,晶粒有所長大,組織不均勻;模具轉角為120°時ES擠壓制備的AZ61鎂合金微觀組織比模具轉角為135°時細小均勻。不同塑性變形參數(shù)下AZ系鎂合金的顯微硬度差異大不,但顯微硬度值較高,達到了60HV左右。對比研究了不同塑性變形方式(擠壓-剪切、正擠壓)和變形溫度下制備的AZ31鎂合金,不同模具轉角及不同原始坯料狀態(tài)下制備的ES變形AZ61鎂合金的往復滑動摩擦磨損行為,根據(jù)摩擦系數(shù)和磨損率變化探索了擠壓-剪切工藝參數(shù)對AZ系鎂合金摩擦磨損性能的影響,結合磨損表面和磨屑的SEM和EDS實驗,分析了不同摩擦工況下的磨損機制。結果表明:ES變形比正擠壓制備的鎂合金耐磨性較好;ES變形溫度為370℃,模具轉角120°下制備的AZ系鎂合金磨損性較好;坯料均勻化與未均勻化制備的ES變形鎂合金耐磨性接近。磨損機制隨法向載荷和往復頻率的增加由輕微磨損的粘著磨損、磨粒磨損和氧化磨損轉變?yōu)閲乐啬p的剝層磨損、塑性變形和熔融磨損。采用DEFORM-3D有限元軟件對擠壓-剪切和正擠壓AZ31鎂合金和不同往復頻率下ES變形AZ31鎂合金的摩擦磨損過程,及加載初期材料受力情況進行了數(shù)值模擬。應力應變場的分布和變化表明:相同摩擦條件下ES變形鎂合金和正擠壓鎂合金相比產(chǎn)生的塑性變形程度較小,耐磨性相對較好;有效應力應變往復隨頻率增加而減小,隨外加載荷增加而增大,累積應力應變可誘發(fā)塑性變形和剝層磨損的發(fā)生,增大金屬表面磨損程度。
[Abstract]:Extrusion-Shear Extrusion-Shear process of magnesium Alloy Extrusion-Shear. ESU is a new plastic deformation technology which combines forward extrusion and equal angular extrusion. The research shows that this process can refine magnesium alloy grain effectively and improve the mechanical properties of magnesium alloy. However, the effect on the friction and wear properties of magnesium alloys has not been studied. Based on the study of microstructure and mechanical properties of es wrought magnesium alloys, the reciprocating friction test is carried out in this paper. The friction and wear properties of es wrought magnesium alloy were studied by numerical simulation. The XRD, metallographic observation, microhardness test and analysis of wrought magnesium alloy prepared under different es deformation temperature, die rotation angle and different blank raw state were carried out. The results showed that the results were compared with that of positive extrusion. The microstructures of AZ series magnesium alloys are more fine and uniform due to the double shearing of die rotation angle in extrusion-shear deformation. When the deformation temperature is 370 鈩，

本文編號：1420788