超超臨界電站用新型鎳基合金熱加工過程的再結(jié)晶機(jī)理分析超超臨界電站用新型鎳基合金熱加工過程的再結(jié)晶機(jī)理分析ANALYSIS OF RECRYSTALLIZATION MECHANISMS IN HOT WORKING PROCESSES OF A NEW NICKEL-BASED ALLOY FOR ULTRA-SUPERCRITICAL POWER PLANT 以一種超超臨界電站用新型鎳基合金為研究對(duì)象，結(jié)合合金管材的冷熱加工過程及系列壓縮熱變形與固溶退火試驗(yàn)，利用光學(xué)顯微鏡和透射電子顯微鏡等手段對(duì)該合金熱加工過程中的動(dòng)、靜態(tài)再結(jié)晶行為進(jìn)行系統(tǒng)分析。結(jié)果表明：新型鎳基合金的動(dòng)態(tài)再結(jié)晶過程以晶界弓彎方式形核的非連續(xù)動(dòng)態(tài)再結(jié)晶為主，靜態(tài)再結(jié)晶則以應(yīng)變誘導(dǎo)晶界遷動(dòng)形核機(jī)制為主。此外，動(dòng)態(tài)再結(jié)晶與靜態(tài)再結(jié)晶過程中產(chǎn)生的不同形態(tài)的臺(tái)階晶界，其本質(zhì)是實(shí)現(xiàn)表面對(duì)低指數(shù)面的偏離，保證更多晶界面為低能密排面，以使晶界界面能降低；其形態(tài)取決于晶界面的晶體學(xué)關(guān)系以及晶界位錯(cuò)的伯氏矢量；臺(tái)階晶界的存在還可以促進(jìn)晶界遷移，加速再結(jié)晶過程。而且，在再結(jié)晶過程進(jìn)行完全后，臺(tái)階晶界仍部分保留，以降低界面能并繼續(xù)促進(jìn)后續(xù)的晶粒長(zhǎng)大過程。 Nickel-based alloy is a good choice for materials used in ultra-supercritical power plant, which are subjected to high temperature of order to 700 ℃ and high pressure in service. In order to meet the requirements above, a new nickel-based alloy has been successfully designed and produced. Based on the hot/cold working process of tube components of the newly designed nickel-based alloy for ultra-supercritical power plant application, microstructural evolution behaviors, especially the recrystallization mechanisms during hot working process of the newly designed alloy were systematically investigated by using a series of hot compression tests, solution annealing tests, optical microscopy and transmission electron microscopy analysis. The results show that dynamic recrystallization is dominated by discontinuous dynamic recrystallization mechanism involving grain boundary bulging, while the nucleation mechanism of strain inducing grain boundary migration is the driving force of static recrystallization. In addition, the essence of different forms of step grain boundary producing during dynamic recrystallization and static recrystallization is to make the surface be of low exponential surface deviation, which can ensure more interface to be low energy close-packed surface, so that the energy of grain boundary interface would be reduced. The morphology of step grain boundary depends on the crystallographic relationship of crystal interface and the Burgers vector of grain boundary dislocation. And the presence of step grain boundary can also promote grain boundary migration and accelerate the recrystallization process. Moreover, when the recrystallization process is completed, step grain boundary still remains partially to minimize interfacial energy and continue to promote subsequent grain growth processes. 全文下載：http://pan.baidu.com/s/1mhLbSd6
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