本文選題：CLAM鋼 + TIG焊��； 參考：《江蘇大學(xué)》2016年碩士論文

【摘要】：中國低活化馬氏體CLAM鋼因其優(yōu)良的熱物理特性以及成熟領(lǐng)先的技術(shù)基礎(chǔ),被普遍認(rèn)為是未來聚變反應(yīng)堆示范電站及商業(yè)化聚變電站的首選包層結(jié)構(gòu)材料。針對CLAM鋼結(jié)構(gòu)材料的工作環(huán)境,研究其焊縫在高溫運(yùn)行條件下的力學(xué)性能變化,對提高其蠕變持久強(qiáng)度及蠕變壽命有著十分重要的理論和現(xiàn)實價值。數(shù)學(xué)建模及合理、正確預(yù)測參數(shù)的選擇將有效地預(yù)測其實際服役條件下的蠕變性能和持久斷裂強(qiáng)度。本文在綜合參考了國內(nèi)外對多種典型RAFM鋼研究方法的基礎(chǔ)上,制定了實驗方案:利用自制焊絲作為填充材料,采用TIG焊工藝對5 mm厚的CLAM鋼板進(jìn)行雙層對接焊。并將焊件分為兩組,其中一組焊后進(jìn)行760℃/30 min的回火處理,另一組不進(jìn)行熱處理,進(jìn)行對比分析。利用現(xiàn)代分析測試手段,觀察兩組焊接接頭的微觀組織形態(tài),測試分析其顯微硬度,沖擊吸收功以及高溫瞬時拉伸強(qiáng)度。另外,利用電子蠕變持久試驗機(jī),對經(jīng)過回火處理的接頭進(jìn)行高溫蠕變試驗,研究分析其蠕變曲線變化規(guī)律及蠕變參數(shù);利用SEM,TEM電子顯微鏡分別觀察蠕變斷口形貌以及蠕變過程中不同時間點焊接接頭微觀組織中的位錯分布;最后根據(jù)Larson-Miller參數(shù),對焊接接頭的長期蠕變斷裂強(qiáng)度進(jìn)行預(yù)測。試驗結(jié)果表明,CALM鋼TIG焊焊接接頭符合正常蠕變規(guī)律,包括瞬時、穩(wěn)態(tài)、快速三個蠕變階段,在溫度一定的情況下,隨著應(yīng)力水平的提高,穩(wěn)態(tài)蠕變速率ε不斷增大,蠕變斷裂時間逐漸縮短。通過冪律方程得到的焊接接頭穩(wěn)態(tài)蠕變階段的應(yīng)力因子n值為15,大于合金材料的典型值3~7。另外,CLAM鋼的激活能Q約為436 KJ/mol.K大于鐵的自擴(kuò)散激活能(300KJ/mol.K),說明在目前應(yīng)力條件和溫度范圍內(nèi),焊接接頭穩(wěn)態(tài)蠕變階段的蠕變變形機(jī)制為位錯蠕變。通過對焊接接頭TEM微觀形貌的觀察發(fā)現(xiàn),在550℃、180 MPa的條件下,隨著蠕變時間的不斷增加,板條馬氏體晶界處的位錯逐漸增多,聚集并產(chǎn)生塞積,阻礙位錯運(yùn)動,減緩蠕變變形,從而使得穩(wěn)態(tài)蠕變階段的蠕變速率減小。借助于斷口形貌學(xué)理論對CLAM鋼焊接接頭的蠕變斷裂行為進(jìn)行分析,斷裂方式為典型的韌性斷裂。此外,韌窩中分布著大小不等的球形顆粒,說明其為等軸韌窩。利用Larson-Miller參數(shù)方程對CLAM鋼TIG焊焊接接頭在550℃/100000 h的服役條件下的高溫蠕變斷裂強(qiáng)度進(jìn)行預(yù)測,其預(yù)測值為106 MPa,接近于母材CLAM鋼140 MPa的服役條件,說明焊接接頭的高溫蠕變性能合格。
[Abstract]:Low activation martensitic clam steel in China is widely considered as the preferred cladding structure material for future fusion reactor demonstration power station and commercial substation due to its excellent thermo-physical properties and mature leading technical foundation. In view of the working environment of clam steel structure material, it is of great theoretical and practical value to study the change of mechanical properties of weld seam under high temperature operation condition, which is of great theoretical and practical value to improve the creep rupture strength and creep life of clam steel structure material. The selection of mathematical modeling and reasonable prediction parameters will effectively predict the creep performance and rupture strength under the actual service conditions. On the basis of comprehensive reference to the research methods of several typical RAFM steels at home and abroad, the experimental scheme has been established in this paper: the 5mm thick clam steel plate was welded by TIG welding process using self-made welding wire as filling material. The welds were divided into two groups. One group was treated with tempering at 760 鈩，

本文編號：2005020