采用改进冲击摆锤，研究7075-T651合金焊缝夏比试样的力?时间曲线。考虑力?时间曲线和恒冲击速率，获得不同区域的断裂能。与焊缝金属(7.88 J)和基体金属(5.37 J(纵向)和7.37 J(横向))的断裂能相比，热影响区的断裂能更高(33.6 J)，这是由于焊接过程中，热力学不稳定的η′相发生组织转变。焊缝区的断裂能比基体合金的高，这是由于焊接凝固过程中产生大量孔洞。为从力?时间曲线中获得动态屈服力，对焊缝、热影响区和基体合金的屈服强度进行近似处理。断裂形貌表明，基体合金在纵向方向上呈现晶间断裂，而在横向方向上，主要为脆性(解理)断裂并伴有韧性断裂特征。而焊缝区和热影响区则呈现韧性断裂。
By using an instrumented impact pendulum, the force versus time curves of 7075-T651 aluminum welds were obtained from standard Charpy-V samples. Considering the force?time curves and constant impact velocity, the fracture energies for different zones were quantified. A fracture energy improvement for the HAZ (33.6 J) was observed in comparison with the weld metal (7.88 J), and base metal (5.37 J and 7.37 J for longitudinal and transverse directions, respectively). This toughness increment was attributed to the microstructural transformation caused by the thermodynamic instability of η′ precipitates during the welding. Fracture energy for weld metal was higher than that for base metal, probably due to pores created during solidification. Regarding the dynamic yielding force obtained from the force?time curves, an approximation to the dynamic yield strength for weld, HAZ and base metal was determined. Fracture surfaces revealed an intergranular failure for base metal in longitudinal direction, whereas a predominately brittle failure (cleavage) with some insights of ductile characteristics was observed for the transverse direction. In contrast, a ductile failure was observed for weld metal and HAZ.
参考文献
| [1] | B. Hu;I.M. Richardson.Microstructure and mechanical properties of AA7075(T6) hybrid laser/GMA welds[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,20071-2(1-2):94-100. |
| [2] | Christian B. Fuller;Murray W. Mahoney;Mike Calabrese;Leanna Micona.Evolution of microstructure and mechanical properties in naturally aged 7050 and 7075 Al friction stir welds[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,20109(9):2233-2240. |
| [3] | N.Alatorre;R.R.Ambriz;B.Noureddine;A.Amrouche;A.Talha;D.Jaramillo.Tensile Properties and Fusion Zone Hardening for GMAW and MIEA Welds of a 7075-T651 Aluminum Alloy[J].金属学报（英文版）,2014(4):694-704. |
| [4] | S.P.Ringer;K.Hono.Microstructural evolution and age hardening in aluminium alloys: atom probe field-ion microscopy and transmission electron microscopy studies[J].Materials Characterization,20001/2(1/2):101-131. |
| [5] | A comparative analysis of tensile and impact-toughness behavior of cold-worked and annealed 7075 aluminum alloy[J].International journal of impact engineering,20104(4):425. |
| [6] | Y. Chen;K.O.Pedersen;A.H. Clausen;O.S. Hopperstad.An experimental study on the dynamic fracture of extruded AA6xxxand AA7xxx aluminium alloys[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,20091/2(1/2):253-262. |
| [7] | S. Sahraoui;J. L. Lataillade.Analysis of load oscillations in instrumented impact testing[J].Engineering Fracture Mechanics,19984(4):437-446. |
| [8] | Nikolaos D. Alexopoulos;Antonis Stylianos;John Campbell.Dynamic fracture toughness of Al-7Si-Mg (A357) aluminum alloy[J].Mechanics of materials,2013Mar.(Mar.):55-68. |
| [9] | P. Landrein;T. Lorriot;L. Guillaumat.Influence of some test parameters on specimen loading determination methods in instrumented Charpy impact tests[J].Engineering Fracture Mechanics,200115(15):1631-1645. |
| [10] | R.R. Ambriz;C. Froustey;G. Mesmacque.Determination of the tensile behavior at middle strain rate of AA6061-T6 aluminum alloy welds[J].International journal of impact engineering,2013Oct.(Oct.):107-119. |
| [11] | P.Vijaya Kumar;G.Madhusudhan Reddy;K.Srinivasa Rao.Microstructure, mechanical and corrosion behavior of high strength AA7075 aluminium alloy friction stir welds — Effect of post weld heat treatment[J].防务技术,2015(4):362-369. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%