(西北工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，西安 710072)
摘 要: 采用ANSYS有限元分析軟件，建立12 mm厚TC4鈦合金平板電子束焊接溫度場和應(yīng)力場的三維有限元數(shù)值計算模型。模型采用圓錐體熱源考慮電子束焊接時的小孔效應(yīng)；材料的熱學(xué)、力學(xué)性能參數(shù)隨溫度變化；相變和熔池內(nèi)液體的對流散熱通過比熱和熱導(dǎo)率的變化實(shí)現(xiàn)。計算結(jié)果表明：鈦合金電子束焊接時，熔池呈典型的卵形分布。高值縱向殘余拉應(yīng)力集中分布在焊縫中心線兩側(cè)距焊縫中心線4 mm的區(qū)域內(nèi)，平板內(nèi)部出現(xiàn)接近材料屈服極限的局部三維殘余拉應(yīng)力狀態(tài)。實(shí)驗(yàn)得到的焊縫宏觀形貌和小孔釋放法檢測到的焊接殘余應(yīng)力對計算結(jié)果進(jìn)行驗(yàn)證, 實(shí)驗(yàn)結(jié)果和計算結(jié)果吻合較好，證明了有限元模型的正確性。
關(guān)鍵字: 鈦合金；電子束焊接；數(shù)值模擬；小孔法；殘余應(yīng)力
（School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract: A three dimensional finite element model used for calculating electron beam welding temperature and stress fields of 12 mm-thickness TC4 titanium alloy plate was developed through employing ANSYS software code. Cone body heat source model was chosen to simulate keyhole effect of electron beam welding. Temperature-dependent thermal and mechanical properties were used. Phase change and liquid convection in molten bath were simulated by the change of specific heat and heat conductivity. The results of the simulation show that the shape of the weld pool is typically oval. The longitudinal stresses with high value mainly lie in the region which extends a distance 4 mm away from the weld centerline. The phenomenon of local three dimensions residual tensile stresses, which are equivalent to the yield stress of the material, appears in the plate center. Macrograph of the fusion zone in the transverse section obtained from experiment and residual stresses determined by hole-drilling method are used to validate the simulated results. The experimental and numerical results are in sufficient overall agreement, which proves the validity of the finite element model.
Key words: titanium alloy; electron beam welding; numerical simulation; hole-drilling method; residual stress
