本文選題：埋弧焊 + 焊后熱處理��； 參考：《青島科技大學(xué)》2017年碩士論文

【摘要】：用中頻感應(yīng)加熱技術(shù)對厚壁埋弧焊工件進(jìn)行焊后熱處理能夠消除焊接過程中產(chǎn)生的殘余應(yīng)力,降低焊接結(jié)構(gòu)變形或開裂的傾向。本文采取實驗研究和數(shù)值模擬相結(jié)合的方法,對厚壁件埋弧焊接過程中以及焊前或焊后中頻感應(yīng)預(yù)熱或熱處理過程中工件的耦合溫度和應(yīng)力場進(jìn)行分析,研究焊接和感應(yīng)加熱工藝參數(shù)對焊后和熱處理后工件殘余應(yīng)力場的影響。首先利用ANSYS軟件對埋弧焊焊接過程中厚板工件的溫度和應(yīng)力場進(jìn)行了模擬計算。選用雙橢球熱源建立了厚板埋弧堆焊的熱力耦合數(shù)值模型,利用“生死單元”法模擬了焊接過程中工件的瞬態(tài)溫度變化情況,獲得了厚板不同位置處溫度隨時間的變化曲線。利用彈塑性理論,模擬了焊接過程中的應(yīng)力場及焊后殘余應(yīng)力分布情況,獲得了不同方向殘余應(yīng)力的分布規(guī)律。結(jié)果表明,熔合區(qū)等效殘余應(yīng)力最大,熱影響區(qū)次之,母材區(qū)最小,其最大數(shù)值分別為234 MPa、188 MPa和50 MPa。對工件焊接過程中的溫度變化及焊后殘余應(yīng)力進(jìn)行了實驗測試,實驗結(jié)果與模擬結(jié)果較為吻合。其次建立了電磁-熱-應(yīng)力耦合模型,模擬了中頻感應(yīng)熱處理過程中厚板工件的電磁場、溫度場及應(yīng)力場,分析了感應(yīng)加熱熱處理后殘余應(yīng)力的分布。結(jié)果表明,感應(yīng)加熱焊后熱處理能明顯降低焊接接頭殘余應(yīng)力值,其中熔合區(qū)減小幅度最大。感應(yīng)熱處理后熔合區(qū)、熱影響區(qū)和母材區(qū)的最大殘余應(yīng)力分別降低到142MPa、134 MPa和36 MPa。利用盲孔法對焊后和熱處理后焊接接頭的殘余應(yīng)力進(jìn)行了測量,實驗結(jié)果與模擬結(jié)果較為吻合。最后利用建立的電磁-熱耦合數(shù)值模型,對大直徑321不銹鋼圓筒件的焊前感應(yīng)預(yù)熱瞬態(tài)溫度場進(jìn)行了模擬分析。研究了感應(yīng)線圈中不同電流大小、頻率以及不同感應(yīng)加熱方式作用下工件的溫度分布情況,通過調(diào)節(jié)電流參數(shù)和感應(yīng)加熱作用方式使得感應(yīng)預(yù)熱后工件加熱區(qū)溫度達(dá)到120±10℃的預(yù)熱工藝要求。結(jié)果表明,最佳感應(yīng)預(yù)熱工藝為采用頻率為10 KHz、大小為750 A的感應(yīng)電流,加熱10 s后停止20 s的間隔加熱模式。
[Abstract]:Post-welding heat treatment of thick wall submerged arc welding workpiece with medium frequency induction heating technology can eliminate the residual stress in welding process and reduce the tendency of deformation or cracking of welding structure. In this paper, the coupling temperature and stress field of thick wall parts during submerged arc welding and in the process of induction preheating or heat treatment with intermediate frequency before or after welding are analyzed by means of experimental study and numerical simulation. The effect of welding and induction heating process parameters on residual stress field of workpiece after welding and heat treatment was studied. At first, the temperature and stress field of plate during submerged arc welding are simulated by ANSYS software. A thermal-mechanical coupled numerical model of thick plate submerged arc surfacing welding was established by using double ellipsoid heat source. The transient temperature variation of workpiece during welding was simulated by "birth and death element" method, and the temperature variation curves at different positions of thick plate with time were obtained. The stress field in welding process and the distribution of residual stress after welding are simulated by using elastic-plastic theory, and the distribution of residual stress in different directions is obtained. The results show that the equivalent residual stress in the fusion region is the largest, the heat affected zone is the second, the base metal region is the smallest, and the maximum values are 234MPA ~ 188 MPa and 50 MPA, respectively. The temperature change and residual stress after welding are tested experimentally. The experimental results are in good agreement with the simulation results. The electromagnetic field, temperature field and stress field of medium frequency induction heat treatment are simulated, and the distribution of residual stress after induction heat treatment is analyzed. The results show that the residual stress of welded joints can be significantly reduced by induction heating post-welding heat treatment, and the fusion zone is the largest. After induction heat treatment, the maximum residual stresses of fusion zone, heat affected zone and base metal region are reduced to 142 MPA ~ 134 MPa and 36 MPA / a respectively. The residual stresses of welded joints after welding and heat treatment were measured by blind hole method. The experimental results are in good agreement with the simulation results. Finally, the transient temperature field of pre-welding induction preheating of large diameter 321 stainless steel cylinder is simulated and analyzed by using the electromagnetic and thermal coupling numerical model. The temperature distribution of the workpiece under the action of different current size, frequency and different induction heating mode in the induction coil is studied. By adjusting the current parameters and the action mode of induction heating, the temperature of the heating zone of the workpiece after induction preheating can reach 120 鹵10 鈩，

本文編號：1830963