(1. 南昌航空大學(xué) 航空制造工程學(xué)院，南昌 330063；
2. 上海航天設(shè)備制造總廠，上海 200245)
摘 要: 采用Nd:YAG激光器實(shí)現(xiàn)200 μm厚Ni47Ti44Nb9形狀記憶合金箔片的焊接，并對(duì)激光工藝參數(shù)進(jìn)行了正交試驗(yàn)。采用光學(xué)顯微鏡觀察接頭的顯微組織，用精密拉伸儀測(cè)試了接頭強(qiáng)度，并用精密硬度計(jì)測(cè)試了接頭的顯微硬度。結(jié)果表明：200 μm厚Ni47Ti44Nb9形狀記憶合金對(duì)接的最優(yōu)激光工藝參數(shù)是平均功率為16.8 W，脈寬為4.4 ms，頻率為4.5 Hz，此時(shí)，接頭的抗拉強(qiáng)度為880 MPa，達(dá)到母材強(qiáng)度的95%。水平面呈均勻的魚(yú)鱗紋狀。橫截面出現(xiàn)了分層現(xiàn)象，焊縫中心為超細(xì)等軸晶，熱影響區(qū)為柱狀組織。縱截面為等軸晶與NiTi-βNb偽共晶析出帶交替分布，焊縫區(qū)的平均硬度大于母材的平均硬度。
關(guān)鍵字: 形狀記憶合金；激光焊接；正交試驗(yàn)；顯微組織
（1. School of Aviation Manufacturing and Engineering, Nanchang Hangkong University, Nanchang 330063, China;
2. Shanghai Spaceflight Manufacture (Group) Co., Ltd., Shanghai 200245, China）
Abstract:The welding joint of Ni47Ti44Nb9 shape memory alloy with thickness of 200 μm was achieved by Nd:YAG laser, and the laser process parameters were investigated by orthogonal experiment. The welding joint microstructure was observed by optical microscopy, the strength of extension of the joint was tested by precision stretcher, and the micro-hardness of the welding joint was tested with the precision hardmeter. The results shows that the best laser parameters of jointing Ni47Ti44Nb9 shape memory alloy with thickness of 200 μm are that the average power is 16.8 W, the width of pulse is 4.5 ms and the frequency is 4.5Hz. At this time, the tensile strength is 880 MPa, reaching 95% strength of the base metal. The horizontal surfaces appear uniform scales striate. And there is a phenomenon of layering on the cross-section, the center of the welding joint is ultrafine axis crystal. The heat affected zone is the column structure. The longitudinal section is exchange distribution of equiaxed grains and pseudoeutectic of NiTi-βNb. The average hardness of the welding joint is greater than that of the base metal.
Key words: shape memory alloy; laser welding; orthogonal experiment; microstructure
