本文選題：鉛鉍共晶合金　切入點(diǎn)：空泡腐蝕　出處：《江蘇大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鉛鉍共晶合金(lead-bismuth eutectic,LBE)是加速器驅(qū)動(dòng)次臨界系統(tǒng)(Accelerator driven sub critical reactor system,ADS)和鉛冷快堆(Lead cooled Fast Reactor,LFR)中重要的冷卻劑候選材料,同時(shí)也是ADS系統(tǒng)的散裂靶候選材料。ADS系統(tǒng)中許多結(jié)構(gòu)部件如核主泵葉輪、管道拐彎處、管道過(guò)流部位的接合處,都采用熔化焊的方法進(jìn)行制造與裝配。而這些部位在與液態(tài)鉛鉍合金做高速相對(duì)運(yùn)動(dòng)時(shí),表面局部區(qū)域會(huì)產(chǎn)生壓力突變區(qū),引起氣泡的形成與潰滅,造成比較嚴(yán)重的空泡腐蝕。CLAM鋼是中國(guó)自主研發(fā)的低活化鐵素體/馬氏體鋼(RAFM鋼),是ADS系統(tǒng)與未來(lái)核電領(lǐng)域聚變示范堆的首選包層結(jié)構(gòu)鋼。焊態(tài)下CLAM鋼焊縫組織主要為粗大、不均勻的板條馬氏體,在整個(gè)ADS冷卻回流管道中屬于薄弱區(qū)域。因此研究CLAM鋼焊接接頭在液態(tài)鉛鉍合金中的空泡腐蝕可以為ADS系統(tǒng)及未來(lái)聚變示范堆能夠更加經(jīng)濟(jì)、安全地應(yīng)用提供理論基礎(chǔ)。本文首先利用手工TIG焊的方法,切割同批次CLAM鋼母材為填充材料,對(duì)5mm厚CLAM鋼板進(jìn)行平板對(duì)接焊,然后自主設(shè)計(jì)液態(tài)金屬空泡腐蝕裝置,將CLAM鋼焊縫與母材兩組試樣在550℃液態(tài)LBE中分別進(jìn)行不同時(shí)間的空泡腐蝕實(shí)驗(yàn)。對(duì)不同時(shí)間空泡腐蝕后的各組試樣的表面形貌、相同面積內(nèi)空蝕坑平均深度及表面粗糙度進(jìn)行分析,并且結(jié)合各組試樣的金相組織及力學(xué)性能研究其母材和焊.縫在液態(tài)鉛鉍中的空泡腐蝕過(guò)程、腐蝕機(jī)理及耐蝕性差異。結(jié)果表明CLAM鋼焊縫與母材的表面粗糙度與平均腐蝕坑深度隨著空泡腐蝕時(shí)間的延長(zhǎng)一直呈現(xiàn)加速上升趨勢(shì),焊縫試樣在液態(tài)鉛鉍中的空泡腐蝕過(guò)程僅為孕育期與加速期。在空泡腐蝕過(guò)程中,母材表現(xiàn)出的耐空蝕性能要大大優(yōu)于焊縫。通過(guò)進(jìn)行焊縫試樣研究焊縫試樣相同時(shí)間空泡腐蝕與靜態(tài)腐蝕后試樣截面的元素變化情況,發(fā)現(xiàn)液態(tài)鉛鉍合金中,溶解與氧化腐蝕和空泡腐蝕會(huì)互相促進(jìn),其聯(lián)合作用會(huì)很大程度的破壞試樣表面,這也是液態(tài)LBE中空泡腐蝕過(guò)程為孕育期、加速期的主要原因。由于焊后熱處理是提高焊縫各項(xiàng)性能最直接且最有效的方法,且不同的焊后熱處理方式會(huì)獲得不同力學(xué)性能的焊縫,因此本文制定了4種不同的焊后熱處理方案,研究其對(duì)CLAM鋼焊縫耐空蝕性的影響。試驗(yàn)結(jié)果表明:調(diào)質(zhì)處理后,CLAM鋼焊縫恢復(fù)至細(xì)小均勻的回火馬氏體組織,無(wú)δ鐵素體,且其綜合力學(xué)性能恢復(fù)至母材水準(zhǔn),耐空蝕性能最好。不同溫度的高溫回火后,其耐空蝕性都得到不同程度的改善,760℃回火后耐空蝕性能最好,其在極大提高焊縫的沖擊韌性時(shí),還保留較高的表面硬度與抗拉強(qiáng)度,綜合力學(xué)性能比較好。而710℃與810℃高溫回火后,其綜合性能都有欠缺,耐空蝕性能次之。推薦焊后回火工藝為:760℃保溫1h。
[Abstract]:Lead-bismuth eutectic LBEs are important coolant candidates for accelerator driven sub critical reactor systems and lead cooled Fast ReactorLFRs. At the same time, it is also the candidate material for spallation target of ADS system. Ads system has many structural components such as the impeller of nuclear main pump, the bend of pipeline, and the junction of pipeline flow. All of them are fabricated and assembled by melting welding. When these parts are moving at high speed with liquid lead-bismuth alloy, there will be a pressure abrupt zone in the local area of the surface, which will cause the formation and collapse of bubbles. The relatively serious cavitation corrosion. Clam steel is a low-activated ferrite / martensite steel RAFM steel developed by China, which is the preferred cladding structure steel for ADS system and future nuclear power field fusion demonstration reactor. The weld structure of CLAM steel under welding condition is mainly coarse. Inhomogeneous lath martensite is a weak area in the whole ADS cooling and reflux pipeline. Therefore, the study of cavitation corrosion of CLAM steel welded joints in liquid lead-bismuth alloy can be more economical for ADS system and future fusion demonstration reactor. In this paper, the method of manual TIG welding is first used to cut the same batch of CLAM steel as filling material, and then the 5mm thick CLAM steel plate is welded by plate butt welding, and then the liquid metal cavitation corrosion device is designed independently. The cavitation corrosion tests of CLAM steel weld and base metal samples were carried out in liquid LBE at 550 鈩，

本文編號(hào)：1619343