本文選題：窄間隙埋弧焊 + 焊接殘余應(yīng)力��； 參考：《華東理工大學(xué)》2017年碩士論文

【摘要】：轉(zhuǎn)子作為核電汽輪機(jī)組核心部件之一,其可靠性和穩(wěn)定性直接決定著汽輪機(jī)組的安全性和使用壽命。目前,焊接轉(zhuǎn)子已經(jīng)成為核電低壓汽輪機(jī)轉(zhuǎn)子的發(fā)展趨勢(shì),分析汽輪機(jī)焊接轉(zhuǎn)子焊接瞬時(shí)應(yīng)力的演化和焊接殘余應(yīng)力分布狀態(tài)對(duì)轉(zhuǎn)子設(shè)計(jì)具有重要的意義�，F(xiàn)階段通過實(shí)驗(yàn)測(cè)量與有限元相結(jié)合的研究方法是探討窄間隙埋弧焊厚壁焊件焊接瞬時(shí)應(yīng)力的演化和焊接殘余應(yīng)力分布狀態(tài)的重要手段,但對(duì)壁厚大于150mm窄間隙埋弧焊厚壁焊件的焊接殘余應(yīng)力分析的文獻(xiàn)比較少。另一方面,焊后熱處理通常作為降低或消除厚壁焊件焊接殘余應(yīng)力的重要手段,而工程中焊后熱處理參數(shù)的設(shè)定大多依靠施工經(jīng)驗(yàn),缺少一定的理論依據(jù)�；诖�,本文以焊接轉(zhuǎn)子模擬件為研究對(duì)象,采用ABAQUS有限元分析軟件,編寫FILM、DFLUX和UEXPAN子程序完成焊接轉(zhuǎn)子模擬件的焊接分析;開展熱處理過程中轉(zhuǎn)子焊接殘余應(yīng)力釋放行為的數(shù)值研究,并討論了焊后熱處理主要參數(shù)對(duì)熱處理過程中應(yīng)力釋放行為的影響。主要完成內(nèi)容及相關(guān)結(jié)論如下:(1)基于熱-力順序耦合方法,研究了焊接轉(zhuǎn)子模擬件焊接瞬時(shí)應(yīng)力的演化和焊接殘余應(yīng)力分布狀態(tài)。研究結(jié)果表明:固態(tài)相變對(duì)焊縫及其附近高應(yīng)力區(qū)焊接殘余應(yīng)力分布狀態(tài)具有明顯的影響,不僅影響該區(qū)域焊接殘余應(yīng)力數(shù)值的大小,甚至影響著焊接殘余應(yīng)力的分布方向;在平行于焊縫外表面路徑上,焊縫及其附近區(qū)域焊接殘余應(yīng)力較大,而遠(yuǎn)離該區(qū)域殘余應(yīng)力逐漸減小到忽略不計(jì);在焊縫中心線路徑上,焊接殘余應(yīng)力整體分布均勻,且應(yīng)力值較大,;無論是平行于外表面的路徑還是焊縫中心線,在焊接過程中,其路徑上的焊接應(yīng)力在后續(xù)焊道添加到一定厚度后都基本不再變化。(2)基于瞬態(tài)熱分析法,引入Norton-Bai1ey蠕變本構(gòu)方程,探討和研究了焊后熱處理過程中應(yīng)力釋放機(jī)制和演化過程。研究結(jié)果表明:焊后熱處理過程中,應(yīng)力釋放的主要機(jī)制是高溫條件下材料發(fā)生的蠕變,而非高溫導(dǎo)致的材料軟化;焊接殘余應(yīng)力的釋放主要發(fā)生在升溫階段,保溫階段應(yīng)力釋放量較小,而降溫階段應(yīng)力有所升高;在焊縫中心線路徑上,當(dāng)材料溫度由外及內(nèi)逐漸高于蠕變溫度時(shí),焊接殘余應(yīng)力表現(xiàn)出明顯的由外及內(nèi)的迅速消除過程。(3)基于控制變量法,探討了焊后熱處理參數(shù)對(duì)熱處理過程中焊接殘余應(yīng)力釋放效果的影響。研究結(jié)果表明.:焊后熱處理溫度是決定殘余應(yīng)力釋放量的關(guān)鍵因素,熱處理過程中焊件中心達(dá)到熱處理溫度是保證熱處理效果的重要環(huán)節(jié);焊后熱處理保溫時(shí)間對(duì)應(yīng)力釋放量的影響不大,在僅考慮應(yīng)力釋放的情況下,可以適當(dāng)?shù)乜s短保溫時(shí)間;通過研究不同壁厚焊件在不同升溫速率下的溫度曲線,為最大升溫速率和最短保溫時(shí)間的選擇提供了一定的理論參考。
[Abstract]:As one of the core components of nuclear turbine unit, the reliability and stability of rotor directly determine the safety and service life of steam turbine unit. At present, welding rotor has become the development trend of nuclear power low-pressure steam turbine rotor. It is very important to analyze the evolution of welding transient stress and the distribution of welding residual stress in steam turbine welding rotor. At present, the research method of combining experimental measurement with finite element method is an important means to discuss the evolution of instantaneous stress and the distribution of residual stress of thick wall welded parts in narrow gap submerged arc welding (SAW). However, there are few literatures on the residual stress analysis of thick wall welding parts with wall thickness greater than 150mm narrow gap submerged arc welding. On the other hand, post-welding heat treatment is usually used as an important means to reduce or eliminate the residual stress of thick wall welds, and the parameters of post-welding heat treatment in engineering are mostly based on construction experience and lack of certain theoretical basis. Based on this, this paper takes the welding rotor simulation as the research object, uses Abaqus finite element analysis software, compiles the FILMMU DFLUX and the UEXPAN subprogram to complete the welding analysis of the welding rotor simulation. Numerical study on residual stress release behavior of rotor during heat treatment was carried out, and the influence of main parameters of post welding heat treatment on stress release behavior during heat treatment was discussed. The main contents and related conclusions are as follows: (1) based on the thermo-mechanical sequential coupling method, the transient stress evolution and residual stress distribution of welded rotor simulators are studied. The results show that the solid phase transformation has an obvious influence on the welding residual stress distribution in the weld and its surrounding high stress zone, which not only affects the magnitude of the welding residual stress value, but also affects the distribution direction of the welding residual stress. On the path parallel to the outer surface of the weld, the welding residual stress in the weld and its adjacent area is larger, but the residual stress in the weld far away from this area is gradually reduced to neglect, and the welding residual stress distributes uniformly on the path of the weld centerline. And the stress value is large, whether the path parallel to the outer surface or the weld centerline, in the welding process, the welding stress on the path is basically no longer changed after the subsequent welding pipe is added to a certain thickness) based on transient thermal analysis, Norton-Bai1ey creep constitutive equation was introduced to study the stress release mechanism and evolution process during post-welding heat treatment. The results show that the main mechanism of stress release during post-welding heat treatment is the creep of the material at high temperature, not the softening of the material caused by high temperature, and the release of residual stress of welding occurs mainly at the stage of heating up. The stress release in the heat preservation stage is small, but the stress in the cooling phase is increased, and in the path of the center line of the weld, when the material temperature is gradually higher than the creep temperature from the outside and inside, Based on the control variable method, the influence of welding parameters on the release effect of welding residual stress during heat treatment was discussed. The results show that: the temperature of post-welding heat treatment is the key factor to determine the amount of residual stress release, and it is an important link to ensure the heat treatment effect that the center of the welding piece reaches the heat treatment temperature during the process of heat treatment. The heat preservation time of post-welding heat treatment has little effect on the stress release amount, and the heat preservation time can be shortened properly by considering only the stress release. The temperature curves of different wall thickness welds at different heating rates are studied. It provides a theoretical reference for the selection of the maximum heating rate and the shortest heat preservation time.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG404;TG441.8

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