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Ti6321钛合金焊接接头高温-中应变率力学性能及微观组织

Mechanical properties and microstructure of Ti6321 titanium alloy welded joints at high temperature and medium strain rate

  • 摘要: 采用Gleeble热模拟试验机对焊接接头不同区域进行了高温-中应变率压缩试验,研究了焊接接头不同区域组织对其力学性能的影响,分析了温度和应变率对其变形过程的影响。结果表明,在高温-中应变率压缩时,热影响区强度最高,母材区较差,焊缝区强度最差。高温下(350℃和550℃),随应变率增加(1 s-1和10 s-1),变形主导因素由应变硬化效应转变为热软化效应。母材绝热剪切敏感性较低,在高温-中应变率压缩变形时沿剪应力最大方向发生大范围晶粒协调变形。由于热影响区组织均匀,应变率的增加相对于温度的增加,更能促进热影响区绝热剪切带的生成。焊缝区压缩时,应力易于在晶界处集中,此时温度对其压缩变形时绝热剪切带的生成更为有利。

     

    Abstract: The Gleeble thermal simulation testing machine was used to conduct high-temperature and medium strain rate compression tests on different areas of the welded joint. The impact of the structure of different areas of the welded joint on its mechanical properties was studied,and the effects of temperature and strain rate on its deformation process were analyzed. The results show that during medium strain rate compression at high temperatures,the heat affected zone exhibits the highest strength,followed by the base metal and the weld metal with relatively lower strength. At high temperatures (350℃ & 550℃),as the strain rate increases (1 s-1 & 10 s-1),the dominant factor in deformation changes from the strain hardening effect to the thermal softening effect. At 350℃,as the strain rate increases,the strength increases;at 550℃,as the strain rate increases,the strength decreases. The base metal has low adiabatic shear sensitivity,and a large range of grain coordinated deformation occurs along the direction of maximum shear stress during the process. Since the microstructure of the heat affected zone is uniform,the increase in strain rate relative to the increase in temperature can promote the generation of adiabatic shear bands in the heat affected zone. When the weld metal is compressed,stress tends to concentrate at the grain boundaries,and the temperature at this time is more favorable for the generation of adiabatic shear bands during compression deformation.

     

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