退火对Ni47Ti44Nb9合金激光焊接接头力学性能与形状记忆效应的影响

为了降低镍钛铌(NiTiNb)宽滞后记忆合金紧固环的制备成本,研究了退火对激光焊接接头力学性能和记忆效应的影响。焊接接头在850℃进行了退火处理。结果表明:焊接接头的组织粗大且不均匀,抗拉强度与延伸率均显著低于母材。经过退火后,再结晶导致焊接接头组织更加均匀;母材与焊接接头抗拉强度均大幅度下降,但延伸率均得到较大提高,尤其是焊接接头的延伸率可以提升到28.57%。退火态焊接接头在-40℃变形13%时表现出接近于母材的形状恢复率。

Influences of annealing on mechanical properties and shape memory effects of laser welding joints of Ni47Ti44Nb9 alloy

In order to reduce the manufacturing cost of fastening rings made of NiTiNb wide hysteresis memory alloy,the influences of annealing on mechanical properties and shape memory effects of laser welding joints were investigated.The welding joints were annealed at 850 oC.The results show that the microstructure of the welding joints is coarse and uneven.The tensile strength and elongation of the joints are significantly lower than those of the base metal.After annealing,recrystallization leads to more uniform microstructure of welding joints.The tensile strength of base metal and welding joints decreases substantially,but the elongation increases greatly.The elongation of welding joints has increased to 28.57%.After 13%bending deformation at-40 oC,the shape recovery rate of the annealed welding joints is close to that of the matrix.