發(fā)布時(shí)間：2019-02-19 08:54

【摘要】：主蒸汽管球三通作為主蒸汽管路中的一種特殊結(jié)構(gòu),在主蒸汽管路中用來分配和改變介質(zhì)的流動(dòng)方向,由于球三通結(jié)構(gòu)和功能的特殊性,使得其在管道領(lǐng)域發(fā)揮著重要的作用�？紤]到主蒸汽管球三通在主蒸汽管路中的重要性以及其發(fā)生事故的危害性,本文采用數(shù)值模擬與安全評定相結(jié)合的方法,對主蒸汽管球三通在含裂紋和挖掉裂紋情況下的安全性進(jìn)行分析與評定,分析了主蒸汽管球三通修復(fù)時(shí)的焊接溫度場以及殘余應(yīng)力場,并進(jìn)一步研究了焊接殘余應(yīng)力與工作載荷的耦合場,研究得出以下結(jié)論:(1)含裂紋主蒸汽管球三通在550℃、18.4MPa額定負(fù)荷下最小Von Mises應(yīng)力為27.3MPa,分布于球體外表面以及主管外表面部分區(qū)域;裂紋兩端處應(yīng)力峰值達(dá)到511MPa�；贕B/T 19624-2004對含裂紋主蒸汽管球三通進(jìn)行安全性評價(jià),失效評定圖與最大容許等效裂紋尺寸得出的結(jié)論一致,認(rèn)為主蒸汽管球三通是不安全的。(2)挖掉裂紋主蒸汽管球三通在550℃、18.4MPa額定負(fù)荷下最小Von Mises應(yīng)力為26.2MPa,分布于球體外表面;應(yīng)力峰值為276MPa,相比于含裂紋情況下應(yīng)力峰值降低了45.9%;按照GB/T 19624-2004對挖掉裂紋的主蒸汽管球三通進(jìn)行安全評定,其結(jié)果是滿足安全要求。(3)采用焊條電弧焊工藝修復(fù)裂紋缺陷,預(yù)熱200℃時(shí)等效殘余應(yīng)力峰值為226MPa;預(yù)熱250℃焊接時(shí),等效殘余應(yīng)力峰值位于焊縫處且達(dá)到210MPa,比預(yù)熱200℃時(shí)減小了 7.6%,等效殘余應(yīng)力分布與預(yù)熱200℃時(shí)大體一致,均關(guān)于焊縫區(qū)域基本對稱。(4)預(yù)熱200℃和250℃兩種焊接條件下的周向殘余應(yīng)力、軸向殘余應(yīng)力分布基本一致,在250℃預(yù)熱條件下焊接,應(yīng)力值有所減小,應(yīng)力梯度降低;周向殘余應(yīng)力和軸向殘余應(yīng)力峰值隨焊接電流的增大而增大,隨焊接速度的增大而減小;提高焊接電流或降低焊接速度,軸向殘余應(yīng)力的增長小于周向殘余應(yīng)力的增長。(5)預(yù)熱200℃焊接時(shí)殘余應(yīng)力與工作載荷的耦合應(yīng)力峰值為292MPa,預(yù)熱250℃焊接時(shí)殘余應(yīng)力與工作載荷的耦合應(yīng)力峰值為275MPa。對球三通在200℃和250℃預(yù)熱條件下進(jìn)行焊接修復(fù)均能夠保證球三通在550℃、18.4MPa的額定負(fù)荷下安全運(yùn)行。
[Abstract]:As a special structure in the main steam pipeline, the main steam pipe ball three-way is used to distribute and change the flow direction of the medium in the main steam pipeline. Because of the particularity of the structure and function of the ball three-way, it plays an important role in the pipeline field. Considering the importance of the main steam pipe ball three-way in the main steam pipeline and the harmfulness of the accident, the method of combining numerical simulation with safety assessment is adopted in this paper. In this paper, the safety of the main steam tube ball three-way in the case of cracks and excavations is analyzed and evaluated. The welding temperature field and residual stress field of the main steam tube ball are analyzed during the repair of the main steam tube ball. The coupling field of welding residual stress and working load is further studied. The following conclusions are obtained: (1) the minimum Von Mises stress of the main steam pipe ball with cracks is 27.3 MPA at 550 鈩，

本文編號：2426331