摘要:
针对厚度为30 mm的TA1工业纯钛试板开展电子束焊接试验。通过对焊接接头的母材、热影响区和焊缝进行微观组织及维氏硬度测试,分析焊接过程对TA1材料组织及性能的影响。将疲劳裂纹扩展特性与接头各区域组织相结合,论述微观组织分布差异对焊接试样宏观裂纹扩展路径及裂纹扩展速率的影响。结果表明:与TA1母材相比,电子束焊接头焊缝及热影响区具有更高的疲劳裂纹扩展抗力,导致疲劳裂纹扩展路径发生偏折并最终偏向母材。与具有等轴α相的母材相比,电子束焊接过程中生成的锯齿α及α柱状晶对疲劳裂纹扩展具有阻碍作用。在应力比为0.1的试验条件下,焊缝处的疲劳裂纹扩展速率最低,热影响区其次,母材最高。
Abstract:
Electron beam welding（ EBW） tests have been conducted on TA1 commercially pure titanium medium plates with a thickness of 30 mm.The effect of EBW welding process on microstructures and properties of TA1 material has been investigated by observing the microstructures and conducting Vickers hardness tests on base metal,heat affected zone and weld seam of the welded joints.The effects of microstructure distributional difference on the macroscopic crack growth path and crack propagation rate of welded specimens are discussed by combining the fatigue crack growth characteristics with the microstructures in different parts of the joint.Test results show that compared with the base metal of TA1,the weld seam and heat affected zone（ HAZ） of the welded joint have higher fatigue crack growth resistance,which leads to the deflection of fatigue crack propagation path and the paths extend to base metal finally.Compared with the base metal with equiaxed α phase,the serrated α and α columnar crystals produced by EBW welding have a restrict impact on the fatigue crack growth,which makes the fatigue crack growth rate of the HAZ and weld seam lower than that of the base metal.Under test conditions with stress ratio of 0.1,the fatigue crack growth rate of weld seam is the lowest,the fatigue crack growth rate of HAZ is the second,and the base metal showes the highest fatigue crack growth rate.
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