(天津大學(xué) 材料科學(xué)與工程學(xué)院，天津 300072)
摘 要: 利用自行研制的超聲沖擊實(shí)驗(yàn)裝置，對(duì)提高LF21鋁合金焊接接頭的疲勞強(qiáng)度進(jìn)行了研究，進(jìn)行了TIG焊LF21鋁合金非承載十字與T型接頭的焊態(tài)及沖擊處理態(tài)對(duì)比疲勞試驗(yàn)。結(jié)果表明：使用TIG焊獲得的LF21鋁合金原始焊接接頭的疲勞強(qiáng)度與其它焊接方法得到的同樣接頭的疲勞強(qiáng)度基本相當(dāng)，試圖采用更高強(qiáng)度級(jí)別的S-N曲線對(duì)其進(jìn)行設(shè)計(jì)時(shí)應(yīng)持慎重態(tài)度。在應(yīng)力比 R=0.5時(shí)，超聲沖擊處理使LF21鋁合金非承載十字焊接接頭(拉伸載荷)的疲勞強(qiáng)度提高了26%，接頭壽命延長(zhǎng)了2～4倍。在應(yīng)力比 R=0.1時(shí)，超聲沖擊處理使T型接頭(三點(diǎn)彎曲載荷)的疲勞強(qiáng)度提高了37%，接頭壽命延長(zhǎng)了4～8倍。在應(yīng)力比 R=-1時(shí)，超聲沖擊處理使T型接頭(三點(diǎn)彎曲載荷)疲勞強(qiáng)度提高了44%，接頭壽命延長(zhǎng)了5～10倍。
關(guān)鍵字: 鋁合金； 疲勞強(qiáng)度； 焊接接頭； 超聲沖擊
LF21 aluminum alloy by ultrasonic peening method
CHEN Jun-mei， LIU Yun-hui
（College of Materials Science and Engineering，
Tianjin University， Tianjin 300072， P.R.China）
Abstract:The ultrasonic peening method was used to improve the fatigue strength of welded joints of aluminum. The S-N curves and fatigue limits ofTIG cruciform and T-shape joints of LF21 aluminum were obtained at both as weldedand peening conditions. The results show that it should be more careful to design according to high strength classic S-N curves， for the tests reveal little difference of the fatigue strength between TIG and other welding methods as in the same form of welded joints. The fatigue strength of cruciform joints of LF21 by ultrasonic peening treatment have been increased by 26% (tension) under the stress ratio R =0.5 and the fatigue life is 2～4 times longer than that of the aswelded ones. When the stress ratio R =0.1， the fatigue strength of T-shape joints havebeen improved by 37% and fatigue life is 4～8 times longer. When R =-1， thefatigue strength of T-shape joints have improved by 44% and fatigue life is5～8 times longer.
Key words: aluminum alloy; fatigue strength; welded joints; ultrasonic peening
