(1. 蘭州理工大學(xué) 甘肅省有色金屬新材料省部共建國家重點實驗室, 蘭州 730050;
2. 青海石油管理局油田建設(shè)有限責(zé)任公司， 敦煌 736202)
摘 要: 研究了攪拌摩擦焊焊接銅合金、 鋁合金時接頭中出現(xiàn)的洋蔥環(huán)結(jié)構(gòu)， 分析其形成及影響因素。 結(jié)果表明： 洋蔥環(huán)的實質(zhì)是攪拌針旋轉(zhuǎn)前進時其帶動的軟化層與上一軟化層塑性金屬間相對移動摩擦疊加后產(chǎn)生的一種軌跡；由于攪拌針區(qū)域摩擦熱輸入不足， 層間新生成的晶核呈彌散分布， 層間與層內(nèi)晶粒形狀不同， 從宏觀上看， 接頭縱剖面上形成了結(jié)構(gòu)重疊的半圓環(huán)結(jié)構(gòu)， 而從橫剖面上就形成了獨特的“洋蔥環(huán)”結(jié)構(gòu)；焊縫中心縱剖面上出現(xiàn)環(huán)間距大小與攪拌針旋轉(zhuǎn)一周向前移動的距離基本相等。
關(guān)鍵字: 攪拌摩擦焊; 洋蔥環(huán)結(jié)構(gòu); 塑性流動; 隧道形缺陷
friction stir welding
（1. State Key Laboratory of Gansu Advanced Nonferrous Metal Materials,
Lanzhou University of Technology, Lanzhou 730050, China;
2. Qinghai Oil Field Construction of Limited Liability Corporation,
Dunhuang 736202, China）
Abstract: The onion rings structures in the joints of Cu alloy and Al alloy welded by friction stir welding were studied, and their formation and influence factors were analyzed. The results show that the key of forming onion rings structure is a trace in a way the plastic metal softened shell layers around the friction stir pin were shifted, superimposed and fractionated between the former plastic layer. The grains between the layers ware dispersed, and which are different from the grains in the layers due to low friction heating in the friction stir pin zone. From macroscopic point of view, the overlapped semicircle structures form in the longitudinal section of the joint while the special onion rings structure emerge in the cross-section. The study also discovered that the distance between the layers in the longitudinal section of the center joint nearly equals to the forward step over which the stir pin rotating a circuit are forced to move forward.
Key words: friction stir welding; onion rings structure; plastic flow; tunnel type defects
