接頭的組織與性能
(湖南大學 材料科學與工程學院, 長沙 410082)
摘 要: 以AM60變形鎂合金薄板為研究對象，分析CO2激光焊后接頭的組織和性能，探討鎂合金激光焊接的工藝特點。結果表明：在合適的工藝參數(shù)下，能獲得表面成型良好、變形小的焊接接頭。金相觀察分析發(fā)現(xiàn)接頭中熱影響區(qū)不明顯，焊縫區(qū)組織致密，晶粒細小，晶界上均勻分布著脆性相(Mg17Al12)，但內部易產生氣孔、裂紋等微觀缺陷。硬度測試結果顯示，焊縫硬度略高，母材和熱影響區(qū)硬度相當。在本實驗條件下采用CO2激光焊能實現(xiàn)AM60鎂合金的焊接，抗拉強度可達母材的94%，斷口表現(xiàn)為混合斷裂。
關鍵字: 變形鎂合金AM60；激光焊接；微觀組織；力學性能
wrought magnesium alloy
AM60 plates welded by laser beam welding
（School of Materials Science and Engineering, Hunan University,Changsha 410082, China）
Abstract:The CO2 laser beam was used to weld the wrought magnesium alloy AM60 plates, the microstructure and mechanical properties of the joints were studied, and the technical characteristics of magnesium alloy laser welding were discussed. The results show that a favorable weld without obvious distortion can be obtained under the suitable parameters. By metallurgical analysis it is found that the heat affected zone is not distinct, and the microstructure in fusion zone presents compact fine grains with brittle intergranular precipitates (Mg17Al12), which often accompanies with micro defects such as porosity and cracking. The result of hardness test shows that the hardness of the weld is slightly high, while the hardness of the base metal is equivalent to that of the HAZ. Under this experimental condition, the wrought magnesium alloy AM60 can be welded by CO2 laser beam welding, and the joint strength is up to 94% of the base metal. The fracture surface is characterized by mixture fracture.
Key words: wrought magnesium alloy AM60; laser beam welding; microstructure; mechanical property
