(1. 北京科技大學(xué) 材料與工程學(xué)院，北京 100083；
2. 中國(guó)電力投資集團(tuán)公司 中電投核電技術(shù)中心(北京)有限公司，北京 100044)
摘 要: 利用透射電子顯微鏡(TEM)研究Super304H奧氏體熱強(qiáng)鋼在650 ℃下不同時(shí)間(10~10000 h)時(shí)效過(guò)程中3種析出相的析出行為，并對(duì)其強(qiáng)化機(jī)理進(jìn)行分析；同時(shí)，利用三維原子探針(3DAP)研究Super304H不銹鋼在650 ℃時(shí)效1 h后富Cu相的早期析出行為。并詳細(xì)分析富Cu相共格應(yīng)變的強(qiáng)化機(jī)制。結(jié)果表明：細(xì)小彌散的富Cu相均勻且高度穩(wěn)定地分布在奧氏體基體上，當(dāng)650 ℃時(shí)效時(shí)間達(dá)到10000 h，球形的富Cu相依然保持在納米級(jí)別，直徑約為32 nm。在時(shí)效過(guò)程中，富Cu相與奧氏體基體始終保持完全共格的關(guān)系。Super304H不銹鋼顯微硬度的顯著提高是由于細(xì)小彌散的富Cu相起到共格應(yīng)變強(qiáng)化的作用，晶內(nèi)較大尺寸的MX相也能夠通過(guò)釘扎位錯(cuò)起到一定的強(qiáng)化作用；晶界上呈鏈狀分布的M23C6相亦具有輔助強(qiáng)化作用。
關(guān)鍵字: Spuer304H；富Cu相；析出相；共格強(qiáng)化
（1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China;
2. CPI Nuclear Power Institute, China Power Investment Corporation, Beijing 100044, China）
Abstract:The precipitation behavior of three precipitate phases in Super304H austenitic heat-resistant steel during long time aging (10-10000 h) at 650 ℃ was investigated by transmission electron microscopy (TEM), and the relevant strengthening mechanism was analyzed. Three dimensional atom probe (3DAP) was used to study the early stage of precipitation behavior of Cu-rich phase of Super304H aged at 650 ℃ for 1 h after solution treatment at high temperature. The coherency strain strengthening mechanism of Cu-rich phase has been investigated in detail. The results show that the dispersed fine Cu-rich precipitates exhibit spherical morphology and keep highly stable in austenite matrix, which have the size of about 32 nm in diameter, even after aging at 650 ℃ for 10000 h. The coherent relationship between Cu-rich phase and matrix is preserved during the whole aging process. Due to the coherency strain strengthening effect of Cu-rich phase, the microhardness of Super304H steel increases significantly; simultaneously, the MX phase can also pin the dislocations to induce the additional strengthening effect. Moreover, the chain-like M23C6 phase precipitated at grain boundaries can also contribute to the strengthening effect for Super304H steel.
Key words: Super304H; Cu-rich phase; precipitate phase; coherent strengthening
