本文關(guān)鍵詞： TTP參數(shù)法 蠕變模型 應(yīng)力松弛 壽命預(yù)測(cè)　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：P92鋼是以Cr-Mo鋼為基礎(chǔ),通過添加V、Nb以及1.8%W元素使得具有高溫抗蠕變性,高熱導(dǎo)性等優(yōu)異性能,成為超(超)臨界機(jī)組主蒸汽管道的重要用材。然而P92鋼在高溫高壓長(zhǎng)期服役時(shí)會(huì)發(fā)生蠕變行為,晶界產(chǎn)生蠕變孔洞使得高溫構(gòu)件失效,因而精確預(yù)測(cè)壽命和持久強(qiáng)度對(duì)高溫爐管的使用年限和設(shè)計(jì)極其重要并從而確保高溫構(gòu)件的安全運(yùn)行。傳統(tǒng)的壽命預(yù)測(cè)TTP參數(shù)法以及基于蠕變的θ投影法和修正法均被提出,但基于TTP參數(shù)法中參數(shù)影響因素及參數(shù)值的敏感性研究關(guān)注較少,蠕變外推的壽命預(yù)測(cè)中相當(dāng)部分主要以預(yù)測(cè)方程是否與蠕變實(shí)驗(yàn)曲線吻合為判定準(zhǔn)則,而對(duì)于人們更為關(guān)注的外推效果的評(píng)述則不夠。同時(shí)基于應(yīng)力松弛方法在此鋼中壽命預(yù)測(cè)鮮有報(bào)道。本論文運(yùn)用P92鋼的數(shù)據(jù),比較分析不同的TTP參數(shù)法壽命預(yù)測(cè)精度并基于M-H參數(shù)法分析不同影響因素壽命預(yù)測(cè)之間的差異；基于蠕變曲線進(jìn)行持久壽命外推中,分析不同蠕變模型持久壽命預(yù)測(cè)的差異并分析了基于蠕變速率的分段擬合法在持久壽命預(yù)測(cè)中的結(jié)果；基于應(yīng)力松弛法轉(zhuǎn)化蠕變數(shù)據(jù)進(jìn)行壽命預(yù)測(cè)的結(jié)果分析等并客觀分析三種方法在壽命預(yù)測(cè)精度上的優(yōu)缺性。主要結(jié)論如下：(1)持久斷裂時(shí)間對(duì)持久壽命外推的精度影響不大,短時(shí)持久斷裂數(shù)據(jù)外推到10萬小時(shí)的持久壽命與所有持久斷裂數(shù)據(jù)外推結(jié)果幾乎一致。應(yīng)力影響因素對(duì)持久壽命預(yù)測(cè)精度影響較大,溫度補(bǔ)償越多的應(yīng)力數(shù)據(jù)段進(jìn)行壽命預(yù)測(cè)精度越高,反之越低且預(yù)測(cè)結(jié)果偏高。傳統(tǒng)TTP參數(shù)法均能較好的進(jìn)行數(shù)據(jù)的歸一并預(yù)測(cè),不同TTP參數(shù)法壽命預(yù)測(cè)精度相差不大,M-S常數(shù)值B的變化和OSD常數(shù)值P的變化對(duì)持久壽命外推結(jié)果影響很大。(2)綜合比較不同蠕變模型進(jìn)行持久壽命外推的分析結(jié)果,結(jié)果表明：復(fù)合模型比θ投影法更好描述P92鋼的蠕變行為；外推蠕變速率時(shí),0投影法的外推結(jié)果發(fā)生較大偏折,而復(fù)合模型的預(yù)測(cè)結(jié)果更接近實(shí)際變化趨勢(shì);5%-50%范圍內(nèi)的斷裂應(yīng)變對(duì)壽命預(yù)測(cè)結(jié)果影響較小,0投影法和復(fù)合模型預(yù)測(cè)的持久壽命值之間差距小。但均在600℃進(jìn)行持久壽命時(shí)預(yù)測(cè)值偏高真實(shí)值；基于蠕變速率與時(shí)間曲線的分段擬合結(jié)果與修正模型持久壽命外推一致；蠕變模型關(guān)聯(lián)Monkman-Grant關(guān)系持久壽命外推曲線偏高于真實(shí)值。(3)運(yùn)用應(yīng)力松弛方法并關(guān)聯(lián)TTP參數(shù)法進(jìn)行持久壽命外推,結(jié)果表明較高溫度時(shí)持久壽命預(yù)測(cè)精度越高,反之越低；在不同溫度下,Norton應(yīng)力指數(shù)大約在9.6到11.6,激活能大致為412 KJ·mol-1,蠕變微觀機(jī)制是位錯(cuò)滑移機(jī)制；通過激活體積的計(jì)算,隨著溫度的升高,激活體積增大。
[Abstract]:P92 steel is based on Cr-Mo steel. By adding VNb and 1.8W elements, P92 steel has excellent properties such as high temperature creep resistance and high thermal conductivity. It has become an important material for the main steam pipeline of supercritical unit. However, the creep behavior of P92 steel will occur during the long service at high temperature and high pressure, and the creep holes in grain boundary will lead to the failure of high temperature components. Therefore, it is very important for the service life and design of high temperature furnace tube to accurately predict the life and lasting strength and to ensure the safe operation of high temperature components. The traditional life prediction TTP parameter method and theta projection method based on creep are used. Amendments were proposed. However, based on the sensitivity study of parameter influencing factors and parameter values in TTP parameter method, less attention has been paid to the life prediction of creep extrapolation. Whether the prediction equation is consistent with the creep experimental curve is the criterion in life prediction of creep extrapolation. However, it is not enough to comment on the extrapolation effect that people pay more attention to. At the same time, there are few reports based on stress relaxation method to predict the life of this steel. In this paper, the data of P92 steel are used. The life prediction accuracy of different TTP parameter method is compared and the difference between different influencing factors is analyzed based on M-H parameter method. In the extrapolation of durable life based on creep curve, the difference of durable life prediction between different creep models is analyzed, and the results of subsection fitting method based on creep rate in durable life prediction are analyzed. The results of life prediction are analyzed based on the creep data transformed by stress relaxation method, and the advantages and disadvantages of the three methods in the accuracy of life prediction are analyzed objectively. The main conclusions are as follows: 1). The rupture time has little effect on the accuracy of the extrapolation of the durable life. The rupture life extrapolated to 100,000 hours is almost consistent with the extrapolation results of all the rupture data, and the stress influencing factors have a great influence on the prediction accuracy of the rupture life. The higher the precision of life prediction in the stress section with more temperature compensation, the lower the prediction result is and the higher the prediction result is. The traditional TTP parameter method can be used to predict the data better. The life prediction accuracy of different TTP parameter methods is not different. The variation of M-S constant B and OSD constant P have a great influence on the extrapolation results of durable life. The results show that the composite model is better than theta projection method in describing the creep behavior of P92 steel. When the creep rate is extrapolated, the extrapolation results of the projection method are deflected greatly, while the predicted results of the composite model are closer to the actual trend. The fracture strain in the range of 5- 50% has little effect on the life prediction results. There is a small difference between the value of durable life predicted by the projection method and the composite model, but the predicted value is higher than the true value when the lasting life is carried out at 600 鈩，

本文編號(hào)：1473087