FeMnSi/NiTiNb复合管旋转挤压界面成形质量研究-中国材料进展

文章信息/Info

Title:: Study on the Surface Forming Quality of FeMnSi/NiTiNb Composite Pipe by Rotary Extrusion

Author(s):: SONG Sinan; JIA Xiongfei; SUN Zhichao; School of Materials Science and Engineering,Northwestern Polytechnical University，Xi’an 710072, China

Keywords:: composite pipe; rotary extrusion; numerical simulation; process parameters; deformation mode

摘要:: 旋转挤压工艺为镍基/铁基形状记忆合金复合管成形提供了可能的新途径，但由于两种材料强度、塑性等差异较大，成形过程中容易出现变形不协调和不均匀，导致界面流速差大、分层等问题。为此设计了3种变形模式，通过有限元模拟研究了坯料温度、挤压比和模具角度对复合管旋转挤压界面成形质量关键指标——界面流动速度差和径向压应力的影响规律。发现：随着坯料温度、挤压比和模具角度的增大，3种变形模式下的界面流动速度差均呈现增大趋势；随着坯料温度的降低和挤压比的增大，3种变形模式的径向压应力均呈现增大趋势；随着模具角度的增大，内定外缩和内扩外缩模式的径向压应力呈现减小趋势，而整体缩径模式的径向压应力却呈现增大趋势；综合比较后确定了旋转挤压合理的变形模式：内扩外缩模式。

Abstract:: The rotary extrusion process provides a possible new way for forming Nibased Fe-based shape-memory alloy composite pipes. However, due to the large differences in strength and plasticity between the two materials, during the forming process, the deformation is not harmonious and non-uniform,which leads to the problems of large flow velocity difference and delamination at the composite pipe interface. For this reason, this paper designed three deformation modes, the effects of billet temperature, extrusion ratio and die angle on the flow velocity difference and radial compressive stress were studied by finite element simulation. It is found that the differences of interfacial flow velocity under the three deformation modes increase with the increase of billet temperature, extrusion ratio and die angle; with the decrease of billet temperature and the increase of extrusion ratio, the radial compressive stresses increase; with the increase of die angle, the radial compressive stresses under the internal fixing and external reduction mode and the internal expansion and external reduction mode show a decreasing trend, however, the radial compressive stress under the overall reduction mode shows an increasing trend. Then the reasonable deformation mode of the rotary extrusion is determined: the internal expansion and external reduction mode.