【摘要】：得益于Inconel 625合金良好的耐腐蝕、抗氧化性能及較高的高溫強度,其常被用于核電、化工、軍事以及海洋等領(lǐng)域。鎳基高溫合金由于合金化種類繁多,成分復(fù)雜,在高溫載荷復(fù)合作用的服役環(huán)境下,其高溫力學(xué)性能會在較窄的溫度區(qū)間內(nèi)發(fā)生明顯的變化。本課題將上述特性界定為Inconel 625合金的溫度敏感特性。本課題以Inconel 625合金溫敏特性為切入點,通過設(shè)計不同參數(shù)下的高溫拉伸實驗以及不同溫度下的高溫蠕變實驗,研究合金抗高溫拉伸與蠕變性能以及對應(yīng)的組織演化規(guī)律與溫度因素的內(nèi)在關(guān)聯(lián)機制。在不同溫度高溫拉伸實驗中發(fā)現(xiàn)Inconel 625合金抗拉強度在650~700℃溫度區(qū)間內(nèi)呈上升趨勢,異于高溫合金抗拉強度隨溫度變化的普遍規(guī)律。在隨后的微觀組織觀察中發(fā)現(xiàn),合金晶粒內(nèi)富鉻M23C6碳化物以及富鈮MC型碳化物在700℃溫度區(qū)間內(nèi)發(fā)生了分解,分別由大塊立方體和不規(guī)則塊體分解為小塊狀立方體和層片狀塊體。在700℃時,由于碳化物的分解產(chǎn)生了質(zhì)點彌散強化效應(yīng)從而導(dǎo)致合金抗拉強度提升。本課題將引發(fā)碳化物的分解的原因推斷為應(yīng)力誘導(dǎo)碳化物分解。在不同應(yīng)變速率高溫拉伸實驗中發(fā)現(xiàn),合金高溫力學(xué)性能參數(shù)與應(yīng)變速率關(guān)聯(lián)性并不高,隨應(yīng)變速率的升高,合金的屈服強度、抗拉強度等參數(shù)的變化均為表現(xiàn)出明顯的規(guī)律性。在微觀組織觀察中發(fā)現(xiàn),隨應(yīng)變速率上升,晶界處富鉻M23C6型碳化物析出形貌由不連續(xù)的球塊狀向連續(xù)的顆粒狀轉(zhuǎn)變。在Inconel 625合金固溶處理實驗中發(fā)現(xiàn),當(dāng)固溶溫度達到1170℃時,晶粒明顯長大,此時平均晶粒尺寸為79μm。在隨后的高溫拉伸實驗中發(fā)現(xiàn),隨固溶溫度升高,試樣延伸率降低,與室溫拉伸實驗結(jié)果相反。除固溶溫度1130℃下的試樣抗拉強度接近未經(jīng)固溶處理拉伸試樣外,其他固溶溫度下的試樣抗拉強度均低于未經(jīng)固溶處理拉伸試樣,且隨固溶溫度上升,試樣抗拉強度下降。在微觀組織觀察中發(fā)現(xiàn),δ相在拉伸溫度為700℃析出,隨著固溶溫度的升高,δ相尺寸及數(shù)量也隨之增加并導(dǎo)致合金高溫塑性下降。在不同溫度高溫蠕變實驗中發(fā)現(xiàn),Inconel 625合金在不同蠕變溫度下表現(xiàn)出了較為明顯的溫度敏感特性,當(dāng)蠕變溫度低于750℃時,試樣長時間處于初始蠕變階段。當(dāng)蠕變溫度高于750℃時,試樣出現(xiàn)了完整的蠕變?nèi)A段,當(dāng)蠕變溫度升至800℃,穩(wěn)定蠕變階段急劇縮短。在對微觀組織觀察中發(fā)現(xiàn),隨蠕變溫度升高,δ相析出量增大,且沿晶界向晶內(nèi)以針狀形式生長。δ相的析出及生長降低了合金的高溫抗蠕變性能,導(dǎo)致在800℃時合金抗蠕變性能急劇下降。
[Abstract]:Inconel 625 alloys are widely used in nuclear, chemical, military and marine fields due to their good corrosion resistance, oxidation resistance and high temperature strength. Because of the variety of alloying and complex composition, the mechanical properties of nickel-based superalloys will change obviously in a narrow temperature range in the service environment of high temperature load. In this paper, the above characteristics are defined as the temperature sensitive properties of Inconel 625 alloy. In this paper, the temperature sensitive characteristics of Inconel 625 alloy are taken as the breakthrough point, and the high temperature tensile test and creep experiment at different temperature are designed. The relationship between the tensile and creep properties of the alloy at high temperature and the relationship between the microstructure evolution law and the temperature factors was studied. The tensile strength of Inconel 625 alloy was found to be increasing in the temperature range of 650 ~ 700 鈩，

本文編號：2395669