采用HJ-III型超声冲击机对MB8镁合金焊接接头焊趾进行表面处理，就不同冲击工艺参数对焊接接头表层组织及力学性能进行测试。结果表明：经过超声冲击处理后，接头焊趾及其附近区域表层组织内的原始粗晶转变为晶界清晰、随机取向的纳米晶粒；焊趾处的应力集中系数得到有效降低，表层硬度及其抗拉强度得到提高；超声冲击前后接头拉伸试样均断于焊趾，接头的拉伸断裂机制为准解理断裂。冲击电流为1.2 A、冲击时间为6 min时，与未超声冲击试样相比，MB8镁合金接头的应力集中系数降低12.04%，焊趾表层最大硬度值提高63.2%，抗拉强度提高33.2%，接头表层金属晶粒细化以及焊趾处应力集中程度的降低是提高MB8镁合金焊接接头力学性能的主要原因。
Surface treatment was carried out on the weld toe of MB8 magnesium alloy welded joint with HJ-III type ultrasonic impact treatment equipment. The surface microstructures and mechanical properties of MB8 magnesium alloy welded joints treated by different impact parameters were investigated. The results indicate that, after ultrasonic impact treatment, the primary coarse grains in the surface layer of weld toe and adjacent area turn into randomly oriented nano-crystalline grains with explicit grain boundary. The stress concentration coefficients at weld toe reduce effectively. The surface hardness and tensile strength of joints improve. The joints before and after ultrasonic impact fracture at the weld toe with tensile failure mechanism of quasi-cleavage fracture. In the impact current of 1.2 A and impact time of 6 min, compared with untreated specimens, the stress concentration coefficients reduce by 12.04%, and the surface maximum hardness and tensile strength of treated welded joints increase by 63.2% and 33.2%, respectively. The grain refining of surface layers and the reduced stress concentration at weld toe are main factors which improve the mechanical properties of MB8 magnesium alloy welded joints.
参考文献
| [1] | 余琨;黎文献;王日初;马正青.变形镁合金的研究、开发及应用[J].中国有色金属学报,2003(2):277-288. |
| [2] | 冯吉才;王亚荣;张忠典.镁合金焊接技术的研究现状及应用[J].中国有色金属学报,2005(2):165-178. |
| [3] | 彭建;朱熹;童小山;潘复生.复合助焊剂对AZ31镁合金TIG焊接头组织与性能的影响[J].中国有色金属学报,2013(11):3141-3146. |
| [4] | 何柏林;周尚谕.镁合金焊接接头疲劳性能研究现状和发展趋势[J].热加工工艺,2012(15):185-187,191. |
| [5] | 高明;曾晓雁;唐海国.MB8镁合金CO2激光焊接工艺及接头性能[J].中国有色金属学报,2011(5):939-944. |
| [6] | 何柏林.超声冲击对镁合金焊接接头疲劳性能的研究现状[J].华东交通大学学报,2011(03):73-77. |
| [7] | 李正;吴圣川;徐道荣;王文先.激光熔修AZ31B镁合金焊趾区材料的疲劳性能[J].失效分析与预防,2011(4):209-212. |
| [8] | 张兰 .AZ31B镁合金焊接接头疲劳性能改善方法研究[D].太原理工大学,2010. |
| [9] | 何柏林;于影霞;余皇皇;江民华;史建平.超声冲击对转向架焊接十字接头表层组织及疲劳性能的影响[J].焊接学报,2013(8):51-54. |
| [10] | 解瑞军;邱小明;陈芙蓉;史志铭.超声冲击实现7A52铝合金焊接接头表面纳米化[J].焊接学报,2014(12):35-38. |
| [11] | 黄丽婷;陈明和;谢兰生;张长清.超声冲击载荷对CP3钛合金焊接接头残余应力的影响[J].航空材料学报,2014(1):52-55. |
| [12] | Brian Vilhauer;Caroline R. Bennett;Adolfo B. Matamoros;Stanley T. Rolfe.Fatigue behavior of welded coverplates treated with Ultrasonic Impact Treatment and bolting[J].Engineering structures,2012Jan.(Jan.):163-172. |
| [13] | A. Berg-Pollack;F. J. Voellmecke;C. M. Sonsino.Fatigue strength improvement by ultrasonic impact treatment of highly stressed spokes of cast aluminium wheels[J].International Journal of Fatigue,20114(4):513-518. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%