本文關(guān)鍵詞：新型高Cr鐵素體耐熱鋼的相變研究　出處：《山東理工大學》2015年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 鐵素體耐熱鋼 冷卻速度 M23C6型碳化物 蠕變強度 持久壽命

【摘要】：對9%-12%Cr鐵素體耐熱鋼進行降低C含量、增加Cr含量及添加Co、Mo、W組元的優(yōu)化調(diào)整,經(jīng)真空感應熔煉爐熔煉并澆注成型,利用差熱分析(DTA)、掃描電鏡(SEM)、X射線衍射(XRD)以及電子蠕變試驗等分析手段研究了加熱溫度、冷卻速度以及回火等熱處理工藝對高Cr鐵素體耐熱鋼顯微組織和力學性能的影響,得到如下結(jié)論:試驗鋼加熱時在600-1100℃之間依次發(fā)生磁性轉(zhuǎn)變、奧氏體形成、M23C6型碳化物溶解和奧氏體向δ-鐵素體轉(zhuǎn)變,奧氏體開始形成溫度為853℃,空冷或以40℃/min的速度冷卻時發(fā)生馬氏體轉(zhuǎn)變,馬氏體開始轉(zhuǎn)變溫度為382℃;含鈮的MC型碳化物非常穩(wěn)定,在試驗加熱溫度范圍不能完全溶解到奧氏體中。1050℃×1h固溶處理后的掃描電鏡顯示試驗鋼組織為典型板條狀馬氏體,在馬氏體板條界及原奧氏體晶界上分布著顆粒狀碳化物,以不同冷卻速度處理后試樣的顯微組織顯示隨著冷卻速度的降低,馬氏體板條逐漸變粗,碳化物的析出相逐漸增多,并在晶界處發(fā)生了聚集長大,X射線衍射分析表明碳化物為M23C6型碳化物,隨著冷卻速度的增大,硬度呈現(xiàn)逐漸升高的趨勢。經(jīng)過1100℃×1h空冷后的組織為典型板條馬氏體和少量δ鐵素體,有MX型未溶碳化物NbC分布在基體中。經(jīng)過1100℃×1h空冷+780℃×2h空冷處理試樣的組織為典型回火馬氏體,基體中主要析出相為M23C6型碳化物。馬氏體-δ鐵素體晶界處的碳化物較粗大成連續(xù)狀分布,馬氏體板條界的析出相較細小。經(jīng)過1100℃×1h空冷+780℃×2h空冷處理后的試驗鋼具有較高蠕變強度,650℃/200MPa的持久壽命為411.4h,650℃/170MPa的持久壽命為1499.1h,持久性能較NIMS公布的T/P92、P/T122耐熱鋼有較大提升。
[Abstract]:The 9%-12%Cr ferritic heat resistant steel for reducing the content of C, increase the content of Cr and Co added, Mo, W group optimization element, by vacuum induction melting furnace smelting and casting, using differential thermal analysis (DTA), scanning electron microscopy (SEM), X ray diffraction (XRD) and electronic creep test the analysis means of heating temperature of heat treatment, cooling rate and tempering process of steel microstructure and mechanical properties of Cr heat resistant high iron, we get the following conclusions: the test steel is heated in the magnetic transition in 600-1100 DEG M23C6 type carbide Austenite Formation, dissolution and austenite to ferrite transformation Austenitic, began to form a temperature of 853 DEG C, air cooling or cooling speed to 40 DEG /min when the martensite transformation occurs, the martensite start temperature is 382 DEG C; MC type carbide containing niobium is very stable in the test temperature range does not dissolve to Scanning electron microscopy.1050 c * 1h after solution treatment of austenitic steel is shown in the test typical lath martensite and granular carbides distributed in martensite lath boundaries and the grain boundaries, the microstructure of the specimens with different cooling rates after the treatment showed that with the decrease of cooling rate, the martensite becomes thick, carbide the precipitates gradually increased, and the coarsening occurs at the grain boundaries, X ray diffraction analysis showed that the M23C6 type carbide carbide, with the increase of cooling rate, the hardness increased gradually. After 1100 DEG C * 1H air cooling after the organization is typical of lath martensite and less ferrite, MX undissolved carbide NbC distributed in the matrix. After 1100 DEG C * 1H air-cooled +780 c * 2H air cooling treatment the microstructure of typical martensite matrix, the main precipitation phase was M23C6 type martensite - Delta iron carbide. The ferrite grain boundary carbide coarsening into a continuous distribution, precipitation of martensite lath boundaries compared to small. After testing steel 1100 c * 1H air cooling +780 c * 2H air cooling after treatment with high creep strength, creep rupture life at 650 for /200MPa 411.4h, lasting life at 650 for /170MPa 1499.1h, durable the performance is published by NIMS T/P92, has greatly improved P/T122 heat resistant steel.

【學位授予單位】：山東理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG142.73

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本文編號：1374273