Tensile Strength and Pseudo-elasticity of YAG Laser Spot Melted Ti-Ni Shape Memory Alloy Wires
Tensile Strength and Pseudo-elasticity of YAG Laser Spot Melted Ti-Ni Shape Memory Alloy Wires
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DOI：
10.2320/matertrans.45.1070
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发表时间：
2004-04
影响因子：
1.2
通讯作者：
Y. Ogata;Masaya Takatugu;Takeshi Kunimasa;K. Uenishi;K. Kobayashi
中科院分区：
文献类型：
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作者：
Y. Ogata;Masaya Takatugu;Takeshi Kunimasa;K. Uenishi;K. Kobayashi
为了研究激光微焊接技术在医疗器械制造中的应用，采用YAG激光对具有伪弹性的Ti-Ni形状记忆合金丝进行了微点焊。通过改变激光功率和脉冲宽度等熔化工艺参数，研究了熔凝过程中材料的显微组织、抗拉强度和伪弹性的变化规律。金属熔宽随着输入能量和脉冲宽度的减小而减小。熔化区为胞状枝晶组织，热影响区为长大胞状组织，胞状尺寸约为3 × 10 μm。点熔丝材的抗拉强度比母材低30%，断裂发生在熔化区，断裂面呈脆性。虽然熔融区域和热影响区域由于较大的晶粒尺寸而没有显示出伪弹性，但是使熔融金属的宽度最小化改善了点熔融样品的整体伪弹性。对于由冷轧丝经点焊和随后的形状记忆热处理制备的样品丝，由于热影响区再结晶形成细晶粒，因此伪弹性得到改善。
In order to investigate the applicability of laser micro welding to the fabrication of medical devices, Ti-Ni shape memory alloy wires with pseudo-elasticity were micro spot melted by using YAG laser. By changing the melting parameters, such as laser power or pulse duration, the evolution in microstructure, tensile strength and pseudo-elasticity was investigated. Melted metal width decreased with decreasing the input energy and pulse duration. The microstructure of melted areas was cellular dendrite structures and that of heat affected areas was grown cell structure with a cell size of about 3∼10 μm. Tensile strength of spot melted wires was 30% lower than that of base metal, and the fracture occurred in melted areas with a brittle fracture surface. Although melted areas and heat affected areas did not show a pseudo-elasticity due to the larger grain size, minimizing the width of melted metal improved the overall pseudo-elasticity of spot melted samples. For the sample wires that were prepared by spot melting of cold rolled wires and by the subsequent heat treatment for shape memorizing, the pseudo-elasticity was improved because heat affected zone recrystallized to form fine grains.