本文選題：P92鋼　切入點(diǎn)：多軸蠕變　出處：《華北電力大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著環(huán)境逐漸惡化和能源格局的變遷,國家對發(fā)電企業(yè)的節(jié)能減排能力提出了更高的要求,發(fā)展高蒸汽參數(shù)的高效超超臨界機(jī)組成為未來火電廠建設(shè)和改造的目標(biāo)。隨著蒸汽參數(shù)的提高,電站鍋爐高溫受熱面對材料的性能提出了進(jìn)一步的要求,蠕變性能作為材料的特性之一是影響高溫高壓管道壽命的重要因素。目前,國內(nèi)外的許多學(xué)者對P92等高溫受熱面鋼材進(jìn)行了蠕變性能的研究,這些研究多是在單軸蠕變試驗(yàn)的基礎(chǔ)上進(jìn)行,考慮到電廠實(shí)際運(yùn)行的狀況,部件多處于多向應(yīng)力狀態(tài),隨即又進(jìn)行了大量缺口試樣的多軸蠕變試驗(yàn)。盡管缺口試樣可以在缺口處形成一定的多軸應(yīng)力狀態(tài),但是所形成的應(yīng)力多軸度在缺口處分布不均程度大,可控性差,對于探究多軸應(yīng)力狀態(tài)下材料的蠕變壽命未能提供充分有效的實(shí)驗(yàn)結(jié)果,所以在單軸和缺口試驗(yàn)的基礎(chǔ)上,本文以P92鋼為研究對象,在650℃的條件下,進(jìn)行了內(nèi)壓條件下的蠕變試驗(yàn)實(shí)驗(yàn)臺搭建,設(shè)計(jì)適當(dāng)?shù)膶?shí)驗(yàn)參數(shù)并與單軸及缺口試驗(yàn)對比,分析其軸向和環(huán)向的蠕變發(fā)展。觀察內(nèi)壓試樣的斷口形貌和微觀組織并與單軸和缺口試驗(yàn)結(jié)果對比,得出內(nèi)壓條件下的多軸蠕變規(guī)律。在試驗(yàn)結(jié)果的基礎(chǔ)上,建立耦合損傷參數(shù)的K-R蠕變模型,通過單軸蠕變試驗(yàn)結(jié)果擬合得出相關(guān)參數(shù),結(jié)合內(nèi)壓實(shí)驗(yàn)結(jié)果分析等效應(yīng)力、第一主應(yīng)力、應(yīng)力多軸度和損傷隨時(shí)間的分布和演變。利用有限元分析多軸度因子和內(nèi)壓管幾何尺寸條件改變對內(nèi)壓條件下多軸試驗(yàn)結(jié)果的影響,并在有限元分析的基礎(chǔ)上提出內(nèi)壓厚壁管道的壽命評估方法。結(jié)果表明:內(nèi)壓條件下的蠕變試驗(yàn)形成的應(yīng)力多軸度范圍在1/3到2/3之間,在相近應(yīng)力水平下內(nèi)壓試樣的壽命小于單軸和缺口試樣,與缺口呈現(xiàn)的缺口增強(qiáng)效應(yīng)相反。由于多軸應(yīng)力對空洞生長的約束作用,內(nèi)壓試樣的應(yīng)變值介于單軸和缺口試樣之間。內(nèi)壓試樣斷裂后的斷口形貌韌窩較淺,呈準(zhǔn)解離特征,微觀形貌下觀察到的孔洞和裂紋多分布于與軸向應(yīng)力垂直方向的晶界及板條界上。在損傷模型的基礎(chǔ)上利用有限元分析得出的斷裂應(yīng)力可以在一定范圍內(nèi)預(yù)測內(nèi)壓管道的壽命。
[Abstract]:With the gradual deterioration of the environment and the change of energy pattern, the state has put forward higher requirements for the energy saving and emission reduction capacity of power generation enterprises. The development of high-efficiency ultra-supercritical units with high steam parameters has become the goal of construction and transformation of thermal power plants in the future. With the increase of steam parameters, the high temperature heating surfaces of power plant boilers have put forward further requirements for the performance of materials. As one of the characteristics of materials, creep property is an important factor affecting the life of high temperature and high pressure pipeline. At present, many scholars at home and abroad have studied the creep property of high temperature heating surface steel such as P92. Most of these studies are carried out on the basis of uniaxial creep tests. Considering the actual operation of the power plant, most of the components are in multidirectional stress state. The multiaxial creep tests of a large number of notched specimens were carried out immediately. Although the notched specimens can form a certain state of multiaxial stress at the notch, the stress multiaxial degree formed by the notched specimen has a large uneven distribution at the notch, and the controllability is poor. The creep life of the material under multiaxial stress can not provide sufficient and effective experimental results. Therefore, on the basis of uniaxial and notch tests, this paper takes P92 steel as an object of study at 650 鈩，

本文編號：1648606