石見見,鄒 群,金 旸,李良才,王興剛,吳奕初,劉向兵
高注量輻照RPV鋼的熱處理微觀結(jié)構(gòu)及其對再輻照損傷行為的影響研究
石見見1,2,鄒群1,金旸1,李良才1,王興剛1,吳奕初2,劉向兵3
(1. 中國艦船研究設(shè)計(jì)中心,湖北 武漢 430064;2. 武漢大學(xué)物理科學(xué)與技術(shù)學(xué)院湖北 武漢 430072;3. 蘇州熱工研究院有限公司江蘇 蘇州 215004)
應(yīng)用三維原子探針和納米壓痕技術(shù)研究了高溫高注量質(zhì)子初始輻照、輻照后退火及再輻照條件下核反應(yīng)堆壓力容器(RPV)鋼中的微結(jié)構(gòu)演變,及其與力學(xué)性能之間的關(guān)系。三維原子探針結(jié)果表明:初始輻照(1.6 dpa)條件下,RPV鋼中產(chǎn)生了大量的富Mn-Ni-Si團(tuán)簇;輻照后經(jīng)500 ℃ 1 h退火處理,富Mn-Ni-Si團(tuán)簇基本回復(fù),但仍然存在少量包含Mn和Ni的穩(wěn)態(tài)團(tuán)簇;再輻照(0.1 dpa和1.6 dpa)時(shí),RPV鋼中又產(chǎn)生了新的富Mn-Ni-Si團(tuán)簇,其數(shù)密度和平均尺寸隨再輻照注量的增加而增加;初始輻照和再輻照的RPV鋼中均未有富Cu原子團(tuán)簇析出。納米壓痕結(jié)果表明初始輻照、輻照后退火和再輻照的RPV鋼中均產(chǎn)生了明顯的硬化現(xiàn)象。穩(wěn)態(tài)團(tuán)簇是退火后的RPV鋼的硬度高于未輻照樣品的硬度的主要原因。富Mn-Ni-Si團(tuán)簇是高溫高注量質(zhì)子輻照國產(chǎn)低Cu含量RPV鋼的一個硬化源。
RPV鋼;三維原子探針;質(zhì)子輻照;富Mn-Ni-Si團(tuán)簇
核反應(yīng)堆壓力容器(Reactor Pressure vessel,簡稱RPV)作為一回路中不可更換的關(guān)鍵設(shè)備,長期在高溫、高壓環(huán)境下經(jīng)受高注量的中子輻照,已經(jīng)成為導(dǎo)致RPV老化的主要原因之一[1]。目前,國產(chǎn)化RPV鋼已批量化用于新建核電站的反應(yīng)堆壓力容器,其服役年限有望達(dá)到60年甚至更長。由于RPV鋼的高注量輻照數(shù)據(jù)稀少,即使匯集國際上獲得的RPV輻照性能研究的有效數(shù)據(jù),仍然無法將法規(guī)中脆化預(yù)測模型可靠地外推至新的服役條件[2]。另一方面,國內(nèi)外特別關(guān)注的到期服役核電站的延壽問題,如何利用RPV鋼熱退火措施緩解輻照脆化、實(shí)現(xiàn)核電機(jī)組延壽,已被多數(shù)國家核電站的延壽項(xiàng)目采用[3-7]。然而,RPV鋼韌性程度的恢復(fù)情況、延壽運(yùn)行期間退火處理后RPV鋼的再輻照脆化機(jī)制等問題,近年來成為研究人員關(guān)注的熱點(diǎn)[8,9]。
常規(guī)服役條件下RPV鋼輻照脆化機(jī)理的研究較多,已經(jīng)報(bào)道的脆化源主要包括了富Cu原子團(tuán)簇、基體缺陷和P、S等微量元素在晶界處的偏析等[10-17]。由于新型RPV鋼中Cu、P等元素的含量受到了嚴(yán)格控制,富Cu原子團(tuán)簇和P、S偏析的影響進(jìn)一步弱化,而基體輻照損傷的影響越來越大[15]。有研究證實(shí),低Cu含量的RPV鋼暴露在較高注量輻照條件下會出現(xiàn)富Mn-Ni-Si團(tuán)簇的新脆化源,比富Cu原子團(tuán)簇的形核率低,需要的孕育注量較高、孕育時(shí)間更長,被稱為后期激增相(Late Blooming Phase,簡稱LBP)[18]。LBP相的出現(xiàn)引起RPV鋼的二次硬化,加速脆化現(xiàn)象(即后期激增效應(yīng))[19,20]。同時(shí),RPV鋼中的LBP相、富Cu原子團(tuán)簇和基體缺陷等微結(jié)構(gòu)在退火處理后可逐漸回復(fù),脆性也得到恢復(fù)??紤]到國產(chǎn)RPV鋼的廣泛使用情況和后續(xù)的延壽問題,研究核反應(yīng)堆國產(chǎn)RPV鋼的高注量(超過設(shè)計(jì)注量)輻照、退火處理和再輻照情況下的微觀結(jié)構(gòu)行為,及其對宏觀力學(xué)性能的影響是有必要的。
事實(shí)上,研究實(shí)際工況條件下的RPV輻照脆化機(jī)理更具實(shí)際意義,但中子輻照耗時(shí)太長,輻照成本高并且中子輻照后的樣品具有放射性,不利于后續(xù)的實(shí)驗(yàn)測試;離子輻照由于具有耗時(shí)短、經(jīng)濟(jì)安全等一系列優(yōu)點(diǎn)被廣泛的用來模擬中子輻照用于核材料輻照損傷研究[21]。本實(shí)驗(yàn)主要利用三維原子探針技術(shù)對納米級原子尺度缺陷的探測敏感性,研究高注量質(zhì)子輻照條件下國產(chǎn)RPV鋼退火處理及再輻照情況下的微結(jié)構(gòu)演變機(jī)理,結(jié)合納米壓痕技術(shù)分析微結(jié)構(gòu)缺陷與宏觀力學(xué)性能之間的關(guān)系。
本實(shí)驗(yàn)樣品為中國一重公司生產(chǎn)的國產(chǎn)A508-3型RPV鋼[Cu含量:0.01%(質(zhì)量分?jǐn)?shù))],其主要化學(xué)元素成分如表1所示。輻照前,樣品表面依次進(jìn)行機(jī)械拋光和電化學(xué)拋光處理,其中電化學(xué)拋光的目的是消除樣品表面因機(jī)械拋光引入的損傷層,輻照樣品尺寸為15 mm3×15 mm3×1 mm3。圖1是SEM和EBSD測量的RPV鋼微結(jié)構(gòu)形貌圖和全歐拉角圖。從圖1中可以看出國產(chǎn)RPV鋼的晶粒尺寸均勻,為后續(xù)輻照實(shí)驗(yàn)提供了一致的初始組織結(jié)構(gòu)。
圖1 國產(chǎn)RPV鋼微結(jié)構(gòu)形貌圖和全歐拉角圖
表1 A508-3型RPV鋼的主要化學(xué)元素成分%(質(zhì)量分?jǐn)?shù))
在中國科學(xué)院近代物理研究所的320 kV高電荷態(tài)離子綜合實(shí)驗(yàn)平臺進(jìn)行質(zhì)子輻照實(shí)驗(yàn),質(zhì)子能量為240 keV,輻照溫度為290±5 ℃[接近實(shí)際工況下RPV所在位置的環(huán)境溫度(壓水堆290 ℃)]。圖2所示為SRIM-2010程序模擬計(jì)算的240 keV質(zhì)子輻照RPV鋼的離位損傷量隨注入深度的分布圖[22]。通常核電站在其設(shè)計(jì)壽期(一般核電站運(yùn)行壽命為40年左右)內(nèi)RPV 鋼經(jīng)受的中子輻照的總注量約為 7× 1019n/cm2(>1 MeV),對應(yīng)的離位損傷量約為0.1 dpa[23]。本實(shí)驗(yàn)選取的初始質(zhì)子輻照注量為8×1017p/cm2,對應(yīng)的峰值區(qū)離位損傷量為1.6 dpa;輻照后的樣品經(jīng)500 ℃ 1 h退火處理,真空度約為2×10-4Pa;退火的樣品再次輻照,輻照注量分別為5×1016p/cm2和8×1017p/cm2,對應(yīng)的峰值處離位損傷量分別為0.1 dpa和1.6 dpa。240 keV質(zhì)子輻照的平均注量率約為1.2×10-4dpa/s。
圖2 SRIM-2010計(jì)算的質(zhì)子輻照RPV鋼的離位損傷量隨注入深度的分布圖
三維原子探針(Three Dimensional Atom Probe Tomography,簡稱3D-APT)表征和分析技術(shù)具有原子級空間分辨率。本實(shí)驗(yàn)采用上海大學(xué)分析測試中心的LEAP 3000 HR型3D-APT裝置對實(shí)驗(yàn)樣品的形貌進(jìn)行觀測,脈沖頻率200 kHz,離子收集速率為0.5%每次激光脈沖,數(shù)據(jù)的三維重構(gòu)和進(jìn)一步定量分析在IVAS 3.6.8分析軟件包上完成。
圖2所示,質(zhì)子輻照RPV鋼材料表面不同深度處的損傷是不同的,根據(jù)Oliver-Pharr方法[24],利用連續(xù)剛度測量技術(shù)可計(jì)算出RPV鋼材料表面不同深度處的硬度。實(shí)驗(yàn)中納米壓痕儀(型號Nano Indenter G200)選用Berkovich壓頭,壓入深度為2 μm,由于樣品的表面效應(yīng)及壓頭幾何形狀的偏差(Berkovich壓頭效應(yīng)),壓痕深度小于50 nm的數(shù)據(jù)離散性較大,本實(shí)驗(yàn)中只討論壓痕深度大于50 nm的結(jié)果。每個試樣選取5個不同的壓入點(diǎn),取平均值進(jìn)行比較,用均方差表示數(shù)據(jù)誤差。
采用3D-APT對RPV鋼中Mn,Ni,Si和Cu元素的三維分布進(jìn)行觀測,從圖3和表3中可以看出,相比于未輻照樣品[15],高注量質(zhì)子輻照的RPV鋼中形成了富Mn-Ni-Si團(tuán)簇;輻照的RPV鋼退火后,富Mn-Ni-Si團(tuán)簇的數(shù)密度明顯減小,平均尺寸變化不明顯,說明大部分富Mn-Ni-Si團(tuán)簇基本回復(fù),有少量包含Mn和Ni原子的穩(wěn)態(tài)團(tuán)簇存在;當(dāng)?shù)妥⒘吭佥椪諘r(shí),RPV鋼中主要存在包含Mn和Ni原子團(tuán)簇,隨著再輻照注量的增加,富Mn-Ni-Si團(tuán)簇的數(shù)密度和平均尺寸均隨之增大;高注量初始輻照和再輻照的RPV鋼中均未發(fā)現(xiàn)富Cu原子團(tuán)簇析出。Edmondson等[25]和Miller等[19]利用3D-APT研究了高注量中子輻照的低Cu含量[<0.1%(質(zhì)量分?jǐn)?shù))]RPV鋼中有富Mn-Ni-Si團(tuán)簇生成。Wells等[20]利用3D-APT研究的高注量中子輻照的RPV鋼中,無論RPV鋼是否含有Cu元素,都會生成富Mn-Ni-Si團(tuán)簇。Miller等[26]也研究了高Ni、低Cu[0.05%(質(zhì)量分?jǐn)?shù))和0.07%(質(zhì)量分?jǐn)?shù))]含量的VVER-1000型RPV鋼在高注量中子輻照條件下的微結(jié)構(gòu)變化,結(jié)果發(fā)現(xiàn)了富Mn-Ni-Si團(tuán)簇的生成,但是并沒有形成富Cu原子團(tuán)簇,隨著中子注量的增加,富Mn-Ni-Si團(tuán)簇的數(shù)密度也隨之增加,但是富Mn-Ni-Si團(tuán)簇的尺寸并沒有明顯的變化;當(dāng)450 ℃退火2 h后,富Mn-Ni-Si團(tuán)簇仍然存在,但450 ℃退火24 h后,富Mn-Ni-Si團(tuán)簇完全消失。同時(shí),Pareige等[27]研究了VVER-440型RPV鋼(Cu含量:0.16%(質(zhì)量分?jǐn)?shù)))中子輻照、輻照后退火及再輻照條件下的微結(jié)構(gòu)演變,實(shí)驗(yàn)觀察到初始輻照條件下RPV鋼中形成富Mn-Ni-Si團(tuán)簇,其中還包含有Cu和P原子;退火(475 ℃ 150 h)后,富Mn-Ni-Si團(tuán)簇完全消失,但有少量富Cu原子團(tuán)簇長大粗化;再輻照則未發(fā)現(xiàn)新的富Cu原子團(tuán)簇形成,同時(shí)證實(shí)了再輻照條件下RPV鋼的脆化源不是該富Cu原子團(tuán)簇。結(jié)合上述中子輻照結(jié)果:說明低Cu含量的國產(chǎn)RPV鋼經(jīng)質(zhì)子加速輻照會產(chǎn)生富Mn-Ni-Si團(tuán)簇,并沒有析出富Cu原子團(tuán)簇。同時(shí)早期的TEM和慢正電子湮沒研究結(jié)果表明,高注質(zhì)子輻照的國產(chǎn)RPV鋼中還產(chǎn)生了位錯環(huán)和空位團(tuán)簇等基體缺陷[28]。高溫退火,可使富Mn-Ni-Si團(tuán)簇、位錯環(huán)和空位團(tuán)簇等缺陷回復(fù)。
在不含Cu或者含有較低Cu的RPV鋼中,富Mn-Ni-Si團(tuán)簇的形成機(jī)理除了空位導(dǎo)致的熱動力學(xué)理論之外,溶質(zhì)原子聚集理論也更重要。富Mn-Ni-Si團(tuán)簇通常沿著位錯線或是在晶界附近形成,在輻照過程中,Si和Ni原子與自間隙原子之間具有很強(qiáng)的結(jié)合作用,同時(shí)輻照產(chǎn)生的位錯環(huán)可以被認(rèn)為是Mn、Ni和Si原子聚集的位置,從而導(dǎo)致了富Mn-Ni-Si團(tuán)簇在位錯環(huán)附近形成。在低Cu含量(0.044%(質(zhì)量分?jǐn)?shù)))的RPV鋼中,富Mn-Ni-Si團(tuán)簇在位錯線附近的組分與在晶界附近的組分非常相似[29]。相比于輻照后退火的RPV鋼,低注量質(zhì)子再輻照(0.1 dpa)的RPV鋼中,富Mn-Ni-Si團(tuán)簇的數(shù)密度明顯增加,雖然質(zhì)子輻照和中子輻照的離位損傷量(0.1 dpa)大致相同,但是由于粒子種類、注量率等的不同,輻照產(chǎn)生的缺陷機(jī)理也是不同的。
圖3 質(zhì)子輻照(I-1.6 dpa)、輻照后退火(PIA)和再輻照(RI-0.1 dpa和RI-1.6 dpa)的RPV鋼中Mn、Ni、Si和Cu元素分布圖
表2 質(zhì)子輻照(1.6 dpa)、退火和再輻照(0.1 dpa和1.6 dpa)的RPV鋼中富Mn-Ni-Si團(tuán)簇的數(shù)密度、平均尺寸和體積分?jǐn)?shù)
其中0是指無限深度處的等效硬度值,*是一個特征長度,與納米壓痕儀的壓頭形狀和材料特性有關(guān),D0是指相對于未輻照樣品的硬度增量。圖5中可以看出初始質(zhì)子輻照樣品的硬度值高于未輻照樣品的硬度值,說明高溫條件下質(zhì)子輻照的RPV鋼出現(xiàn)了明顯的硬化現(xiàn)象。RPV鋼硬化的原因是質(zhì)子輻照導(dǎo)致RPV鋼的微結(jié)構(gòu)發(fā)生了變化,通常指質(zhì)子輻照RPV鋼中產(chǎn)生的微結(jié)構(gòu)缺陷(包括空位團(tuán)、位錯環(huán)、微孔洞和溶質(zhì)原子團(tuán)簇或析出相等)阻礙了位錯的運(yùn)動,從而造成了RPV鋼的硬化。退火樣品(PIA)的硬度值明顯低于初始輻照樣品的硬度值,但是又略微高于未輻照樣品的硬度值。說明質(zhì)子輻照的RPV鋼經(jīng)退火處理后,輻照產(chǎn)生的缺陷基本回復(fù),同時(shí),退火后的樣品中仍然存在一些穩(wěn)態(tài)的缺陷(比如3D-APT結(jié)果給出的富Mn-Ni-Si團(tuán)簇)。再輻照樣品的硬度值隨輻照注量的增加而增加,說明再輻照的樣品中又產(chǎn)生了新的缺陷,包括空位、空位團(tuán)、溶質(zhì)原子/H-空位復(fù)合體和位錯環(huán)等基體缺陷以及溶質(zhì)原子團(tuán)簇(比如富Mn-Ni-Si團(tuán)簇)等。高注量再輻照(RI-1.6 dpa)樣品的硬度值高于初始輻照(I-1.6 dpa)樣品的硬度值,但二者中富Mn-Ni-Si團(tuán)簇的平均尺寸基本相同,且前者的富Mn-Ni-Si團(tuán)簇的數(shù)密度低于后者,說明高注量再輻照條件下RPV鋼中形成了新的更多或更大的基體缺陷(如大尺寸的空位團(tuán)、位錯環(huán)等)[8,28]。綜上所述,除了位錯環(huán)、空位型團(tuán)簇等基體缺陷導(dǎo)致RPV鋼硬化[28],富Mn-Ni-Si團(tuán)簇也是高注量質(zhì)子輻照低Cu含量RPV鋼的一個硬化源。
圖4 質(zhì)子輻照(I-1.6 dpa)、輻照后退火(PIA)、再輻照(RI-0.1 dpa和RI-1.6 dpa)和未輻照(Unirr.)的RPV鋼的平均硬度隨壓痕深度的分布圖
圖5 初始輻照(I-1.6 dpa),輻照后退火(PIA)及再輻照(RI-0.1 dpa和RI-1.6 dpa)RPV鋼的硬度增量變化趨勢
通過3D-APT和納米壓痕技術(shù)對高注量輻照條件下國產(chǎn)RPV鋼退火及再輻照的微結(jié)構(gòu)及宏觀力學(xué)性能研究表明:
(1)高溫高注量質(zhì)子輻照條件下低Cu含量RPV鋼中產(chǎn)生了LBP相-富Mn-Ni-Si團(tuán)簇,并沒有形成富Cu原子團(tuán)簇。
(2)退火處理能夠使RPV鋼中的富Mn-Ni-Si團(tuán)簇回復(fù),硬度降低,但存在少量包含Mn和Ni原子的穩(wěn)態(tài)團(tuán)簇。再輻照時(shí),富Mn-Ni-Si團(tuán)簇的數(shù)密度和平均尺寸均隨再輻照注量的增加而增加。
(3)高注量再輻照RPV鋼的硬度值高于初始輻RPV鋼的硬度值,歸因于高注量再輻照條件下RPV鋼中形成了新的更多或更大的基體缺陷。
(4)富Mn-Ni-Si團(tuán)簇是高溫高注量輻照條件下國產(chǎn)低Cu含量RPV鋼的一個硬化源。
[1] 喬建生,尹世忠,楊文.反應(yīng)堆壓力容器材料輻照脆化預(yù)測模型研究[J].核科學(xué)與工程,2012,32(02):143-149.
[2] Ballesteros A,Ahlstrand R,Bruynooghe C,et al. The role of pressure vessel embrittlement in the long term operation of nuclear power plants[J].Nuclear Engineering and Design,2012,243:63-68.
[3] 張敬才.先進(jìn)壓水堆反應(yīng)堆壓力容器面臨的脆化問題[J].核科學(xué)與工程,1987(02):184-187.
[4] Eason E D,Wright J E,Nelson E E,et al. Embrittlement recovery due to annealing of reactor pressure vessel steels[J].Nuclear Engineering and Design,1998,179(3):257-265.
[5] 王英杰,趙宇強(qiáng).影響反應(yīng)堆壓力容器鋼輻照脆性的因素及控制措施[J].核科學(xué)與工程,2011,31(04):327-330+344.
[6] Vassilaros M G,Mayfield M E,Wichman K R. Annealing of nuclear reactor pressure vessels[J].Nuclear Engineering and Design,1998,181(1):61-69.
[7] 張敬才.在役反應(yīng)堆壓力容器延壽探討[J].核動力工程,2003,24(04):293-296.
[8] Toyama T,Kuramoto A,Nagai Y,et al. Effects of post- irradiation annealing and re-irradiation on microstructure in surveillance test specimens of the Loviisa-1 reactor studied by atom probe tomography and positron annihilation[J].Journal of Nuclear Materials,2014,449(1-3):207-212.
[9] Kuramoto A,Toyama T,Nagai Y,et al. Microstructural changes in a Russian-type reactor weld material after neutron irradiation,post-irradiation annealing and re-irradiation studied by atom probe tomography and positron annihilation spectroscopy[J].Acta Materialia,2013,61(14):5236-5246.
[10] Buswell J T,Phythian W J,McElroy R J,et al. Irradiation-induced microstructural changes,and hardening mechanisms,in model PWR reactor pressure vessel steels[J].Journal of Nuclear Materials,1995,225:196-214.
[11] Odette G R,Alinger M J,Wirth B D. Recent developments in irradiation-resistant steels[J].Annual Review of Materials Research,2008,38:471-503.
[12] Nishiyama Y,Onizawa K,Suzuki M,et al. Effects of neutron-irradiation-induced intergranular phosphorus segregation and hardening on embrittlement in reactor pressure vessel steels[J].Acta Materialia,2008,56(16):4510-4521.
[13]萬強(qiáng)茂,束國剛,王榮山,等.法國900 MWe壓水堆RPV中子輻照脆化壽命管理策略研究[J].核科學(xué)與工程,2011,31(04):372-384.
[14]Liu X B,Wang R S,Ren A,et al. Positron annihilation study of proton-irradiated reactor pressure vessel steels[J].Radiation Physics and Chemistry,2012,81(10):1586-1592.
[15]Jiang J,Wu Y C,Liu X B,et al. Microstructural evolution of RPV steels under proton and ion irradiation studied by positron annihilation spectroscopy[J].Journal of Nuclear Materials,2015,458:326-334.
[16]Nagai Y,Tang Z,Hassegawa M,et al. Irradiation-induced Cu aggregations in Fe:An origin of embrittlement of reactor pressure vessel steels[J].Physical Review B,2001,63(13):134110.
[17]徐遠(yuǎn)超,賈學(xué)軍,張長義,等.低銅壓力容器鋼輻照脆化效應(yīng)實(shí)驗(yàn)研究[J].核科學(xué)與工程,1998(02):3-5.
[18]Odette G R,Nanstad R K,Predictive Reactor Pressure Vessel steel irradiation embrittlement Models:issues and opportunities. JOM,2009;61(7):17-23.
[19]Miller M K,Powers K A,Nanstad R K,et al. Atom probe tomography characterizations of high nickel,low copper surveillance RPV welds irradiated to high fluences[J].Journal of Nuclear Materials,2013,437(1):107-115.
[20]Wells P B,Yamamoto T,Miller B,et al. Evolution of manganese-nickel-silicon-dominated phases in highly irradiated reactor pressure vessel steels[J].Acta Materialia,2014,80:205-219.
[21]Was G S,Busby J T,Allen T,et al. Emulation of neutron irradiation effects with protons:validation of principle[J].Journal of Nuclear Materials,2002,300(2-3):198-216.
[22]Ziegler J F,Ziegler M D,Biersack J P. SRIM-The stopping and range of ions in matter(2010)[J].Nuclear Instruments and Methods in Physics Research Section B:Beam Interactions with Materials and Atoms,2010,268(11-12):1818-1823.
[23]Lambrecht M,Malerba L,Almazouzi A. Influence of different chemical elements on irradiation-induced hardening embrittlement of RPV steels[J].Journal of Nuclear Materials,2008,378(3):282-290.
[24]Oliver W C,Pharr G M. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments[J].Journal of Materials Research,2011,7(6):1564-1583.
[25]Edmondson P D,Parish C M,Nanstad R K. Using complimentary microscopy methods to examine Ni-Mn- Si-precipitates in highly-irradiated reactor pressure vessel steels[J].Acta Materialia,2017,134:31-39.
[26]Miller M K,Chernobaeva A A,Shtrombakh Y I,et al. Evolution of the nanostructure of VVER-1000 RPV materials under neutron irradiation and post irradiation annealing[J].Journal of Nuclear Materials,2009,385(3):615-622.
[27]Pareige P,Radiguet B,Krummeich-Brangier R,et al. Atomic-level observation with three-dimensional atom probe of the solute behaviour in neutron-,ion-or electron- irradiated ferritic alloys[J].Philosophical Magazine,2005,85(4-7):429-441.
[28]Shi J J,Zhao W Z,Wu Y C,et al. Evolution of microstructures and hardening property of initial irradiated,post-irradiation annealed and re-irradiated Chinese-type low-Cu reactor pressure vessel steel[J].Journal of Nuclear Materials,2019,523:333-341.
[29]Fukuya K,Ohno K,Nakata H,et al. Microstructural evolution in medium copper low alloy steels irradiated in a pressurized water reactor and a material test reactor[J].Journal of Nuclear Materials,2003,312(2):163-173.
[30] Nix W D,Gao H. Indentation size effects in crystalline materials:A law for strain gradient plasticity[J].Journal of the Mechanics and Physics of Solids,1998,46(3):411-425.
[31]Kasada R,Takayama Y,Yabuuchi K,et al. A new approach to evaluate irradiation hardening of ion-irradiated ferritic alloys by nano-indentation techniques[J].Fusion Engineering and Design,2011,86(9-11):2658-2661.
Study on Post-irradiation Annealing Microstructure and its Effect on Re-irradiation Damage of Highly Irradiated RPV Steel
SHI Jianjian1,2,ZOU Qun1,JIN Yang1,LI Liangcai1,WANG Xinggang1,WU Yichu2,LIU Xiangbing3
(1.China Ship Development and Design Center,Wuhan of Hubei Prov. 430064,China;2.School of Physics and Technology,Wuhan University,Wuhan of Hubei Prov. 430072,China;3.Suzhou Nuclear Power Research Institute,Suzhou of Jiangsu Prov. 215004,China)
Three-dimensional atomic probe tomography(3D-APT)and nanoindentation techniques were used to study the evolution of microstructures and hardening property of high-dose initial proton-irradiated,post-irradiation annealed and re-irradiated reactor pressure vessel(RPV)steel under high temperature. The 3D-APT results indicated Mn-Ni-Si-enriched clusters were produced in initial-irradiated(1.6 dpa)RPV steel. After post-irradiation annealed at 500 ℃ for 1 h,some Mn-Ni-Si-enriched clusters recovered,but a small amount of stable clusters containing Mn and Ni still remained. The Mn-Ni-Si-enriched clusters were formed and their number density and average size increased with the increasing of re-irradiation dose up to 1.6 dpa. No Cu-enriched clusters were precipitated in initial and re-irradiated RPV steels. The nanoindentation results identified that the obvious hardening phenomena were found in the initial irradiated,post-irradiation annealed and re-irradiated RPV steels. The stable clusters were responsible for that the hardness of the post-irradiation annealed RPV steel was higher than that of the unirradiated sample. The Mn-Ni-Si-enriched cluster was an irradiation hardening source of highly irradiated Chinese-type low-Cu RPV steel.
RPV steel;3D-APT;Proton irradiation;Mn-Ni-Si-enriched clusters
TL351+.6
A
0258-0918(2021)05-1060-07
2020-11-02
國家自然科學(xué)基金項(xiàng)目(11675132)
石見見(1990—),男,湖北武漢人,工程師,現(xiàn)主要從事核反應(yīng)堆輻照防護(hù)方面研究