(1. 南昌航空大學(xué)材料科學(xué)與工程學(xué)院，南昌 330063；
2. 季華實(shí)驗(yàn)室，佛山 528000)
摘 要: 建立Ti-6Al-4V合金三維有限元模型，探究低功率密度下不同的激光體能量密度對(duì)選區(qū)激光熔化多層沉積成形過程熱行為及熱應(yīng)力演變的影響。本模擬采用熱-結(jié)構(gòu)間接耦合的方式計(jì)算應(yīng)力場，利用Sqarse/PCG自動(dòng)求解器增加其收斂性。結(jié)果表明：隨著低功率密度下激光體能量能量密度從37.04J/mm3增加至74.07J/mm3，溫度分布具有相似的變化趨勢，熔池深度及寬度先增大后趨于平穩(wěn)，實(shí)驗(yàn)熔寬與模擬結(jié)果基本一致。隨著激光體能量密度的增加，整體殘余應(yīng)力呈減小趨勢，降幅6.30%。表面應(yīng)力呈“條帶狀”周期性分布，應(yīng)力集中處于掃描軌道的搭接區(qū)域，基板層邊緣處應(yīng)力較大。通過對(duì)比模擬與實(shí)驗(yàn)層間殘余應(yīng)力結(jié)果，可見隨著體能量密度的增加兩者具有相同的變化趨勢，最大偏差6.28%。在能量密度為37.04~74.07J/mm3范圍內(nèi)，經(jīng)線性擬合后，模擬/實(shí)驗(yàn)層間殘余應(yīng)力與硬度值呈反比關(guān)系。
關(guān)鍵字: 激光體能量密度；SLM；Ti-6Al-4V；熱應(yīng)力演變；層間殘余應(yīng)力
（1. School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, China;
2.Jihua Laboratory, Foshan 528000, China）
Abstract:The three-dimensional finite element model of Ti-6Al-4V alloy was established to study the effect of different laser energy densities on the thermal behavior and thermal stress evolution of the selective laser melting multi-layer deposition processat low power density. In this simulation, the thermal-structural indirect coupling method was used to calculate the stress field, and the Sqarse/PCG automatic solver was used to increase its convergence. The study results show that, as the energy density of the laser body increases from 37.04J/mm3 to 74.07J/mm3 atlow power density, the temperature distributions have a similar changing trend. The depth and width of the molten pool first increase and then become stable. The experimental molten pool width and simulation results are basically the same. As the energy density of the laser body increases, the overall residual stress shows a decreasing trend, and the decrementis 6.30%. The surface stress is periodically distributed in a “Stripe” shape, the stress is concentrated in the overlap area of the scanning track, and the stress at the edge of the substrate layer is relatively large. Comparing the results of simulated with the experimental interlayer residual stress, it can be seen that as the volume energy density increases, both of them have the same changing trend, and the maximum deviation is 6.28%. Within theenergy density range of 37.04-74.07J/mm3, the simulated/experimental interlayer residual stressesare inversely proportional to the hardness values after fitting.
Key words: laser volume energy density; SLM; Ti-6Al-4V; thermal stress evolution; interlayer residual stress
