本文選題：SA738Gr.B鋼 + AP1000核電��； 參考：《太原理工大學(xué)》2015年博士論文

【摘要】：低合金高強(qiáng)鋼SA738Gr.B與雙相不銹鋼S32101首次應(yīng)用于三代核電AP1000建設(shè)中。SA738Gr.B主要用于鋼制安全殼拼焊，與混凝土安全殼一起組成核電安全的最后一道屏障。S32101雙相不銹鋼主要應(yīng)用于結(jié)構(gòu)模塊，，而且要和硼酸介質(zhì)接觸，對(duì)強(qiáng)度及耐蝕性有較高的要求。研究?jī)煞N鋼材的焊接性能，保證接頭在服役過(guò)程中具有良好的性能是本研究的重要任務(wù)。 本研究采用熱模擬的方法測(cè)定并繪制了SA738Gr.B的SHCCT轉(zhuǎn)化曲線。結(jié)果表明：隨著冷卻速度的降低，熱影響區(qū)組織將先后發(fā)生貝氏體、貝氏體+先共析鐵素體、貝氏體+先共析鐵素體+珠光體的組織轉(zhuǎn)變，硬度相應(yīng)降低。采用Gleeble-1500試驗(yàn)機(jī)模擬了熱影響區(qū)，分析了焊接HAZ的過(guò)熱區(qū)，正火區(qū)，不完全正火區(qū)組織、沖擊韌性的變化和多層多道焊時(shí)的熱影響區(qū)組織變化。焊接過(guò)程中當(dāng)t8/5的數(shù)值在10-15秒時(shí)，其沖擊韌性值最佳。為研究其熱影響區(qū)組織的變化規(guī)律提供了依據(jù)。 通過(guò)斜Y坡口抗裂性試驗(yàn)和插銷試驗(yàn)及Z向拉伸試驗(yàn)方法分析了SA738Gr.B鋼板的焊接性。斜Y坡口試驗(yàn)證明，當(dāng)預(yù)熱溫度超過(guò)100℃，接頭無(wú)裂紋產(chǎn)生。該鋼具有較高的抗Z向冷裂性能，Z向抗裂性試驗(yàn)的斷面收縮率大于35%。插銷試驗(yàn)在預(yù)熱和不預(yù)熱的條件下，粗晶區(qū)的抗強(qiáng)度均大于鋼材的最小抗拉強(qiáng)度，表明粗晶區(qū)亦具有較好的抗冷裂性能，SA738Gr.B具有較好的焊接性。 研究了低合金鋼SA738Gr.B配套專用焊材，成功研發(fā)了鐵粉型焊條E9018-G-H4和ER90S-G焊絲。通過(guò)實(shí)驗(yàn)研究證實(shí)，當(dāng)鐵粉含量在15%且碳酸鈣-螢石比例為1.6:1左右時(shí)，焊條具有較好的工藝性能和良好的力學(xué)性能。研究了實(shí)芯焊絲熔敷金屬碳當(dāng)量和合金元素對(duì)焊縫力學(xué)性能的影響。結(jié)果表明，隨著碳當(dāng)量的提高，熔敷金屬抗拉強(qiáng)度和屈服強(qiáng)度提高。Ni元素顯著影響熔敷金屬的低溫沖擊韌性，當(dāng)鎳元素含量在1%左右時(shí)其低溫沖擊韌性較高。該種焊條已經(jīng)應(yīng)用于AP1000鋼制安全殼的焊接，使用量已達(dá)320噸。 在鋼板焊接性及焊材研究的基礎(chǔ)上進(jìn)行了接頭力學(xué)性能的研究。研究表明，焊接線能量對(duì)接頭的沖擊韌性有著顯著影響。隨著線能量的增加，沖擊韌性值先增加后減小。SA738Gr.B鋼板合適的工藝是預(yù)熱+小線能量。焊后熱處理對(duì)接頭的性能有重要影響，在熱處理過(guò)程中，接頭會(huì)發(fā)生回復(fù)和再結(jié)晶等變化。隨著熱處理時(shí)間的延長(zhǎng)，晶粒有長(zhǎng)大的趨勢(shì)，碳化物等向晶界析出，晶內(nèi)位錯(cuò)密度下降，造成其沖擊韌性下降。 現(xiàn)場(chǎng)的工程實(shí)踐表明，研制的焊接材料和依據(jù)本研究結(jié)果確定的焊接工藝均可滿足SA738Gr.B核電安全殼的技術(shù)要求，焊接質(zhì)量達(dá)到ASME III和技術(shù)條件的要求，獲得了國(guó)內(nèi)外同行的認(rèn)可。 雙相鋼焊接對(duì)線能量敏感，出現(xiàn)熱影響區(qū)韌性降低及耐蝕性能下降。通過(guò)固溶處理可完全恢復(fù)韌性及耐蝕性能，甚至可達(dá)到與母材相接近的程度。為進(jìn)一步研究溫度對(duì)雙相鋼接頭的影響，將固溶處理后的接頭在500℃、600℃、700℃、800℃、900℃下分別時(shí)效30min，測(cè)試結(jié)果表明，沖擊韌性和耐蝕性隨時(shí)效溫度增加先降低后增加，700℃是S32101雙相不銹鋼焊接接頭性能惡化的最敏感溫度。S32l0l不銹接頭進(jìn)行700℃時(shí)效處理結(jié)果表明，Cr2N在晶內(nèi)析出及生長(zhǎng)，造成貧鉻的二次奧氏體是造成塑性、韌性降低和耐腐蝕性能的根本原因。 現(xiàn)場(chǎng)的工程實(shí)踐表明，研制的焊接材料和依據(jù)本研究結(jié)果確定的焊接工藝均可滿足AP1000核電安全殼的技術(shù)要求，焊接質(zhì)量達(dá)到ASME III和技術(shù)條件的要求，獲得了國(guó)內(nèi)外同行的認(rèn)可。
[Abstract]:Low alloy high strength steel SA738Gr.B and dual phase stainless steel S32101 are first applied to the three generation nuclear power AP1000 construction..SA738Gr.B is mainly used for the welding of steel safety shell. The last barrier of nuclear safety with concrete safety shell,.S32101 double phase stainless steel is mainly applied to the structure module, and it should be contacted with boric acid medium, strength and resistance. It is important to study the welding properties of the two steels and ensure the good performance of the joints during service.
In this study, the SHCCT transformation curve of SA738Gr.B was measured and plotted by the method of thermal simulation. The results showed that with the decrease of cooling rate, the microstructure of the heat affected zone would occur successively, bainite + pre eutectoid ferrite, bainite + pre eutectoid and pearlite, and the hardness correspondingly decreased. The Gleeble-1500 test machine die was adopted. The heat affected zone is proposed, and the microstructure changes of the superheated zone, the normalizing zone, the incomplete normalizing zone, the impact toughness and the heat impact zone during multi-channel and multi pass welding of the welded HAZ are analyzed. In the welding process, when the value of t8/5 is 10-15 seconds, the impact toughness is the best. It provides a basis for the study of the change law of the microstructure in the thermal shadow zone.
The weldability of the SA738Gr.B steel plate was analyzed by the slanting Y slope crack resistance test, the bolt test and the Z tensile test. The slanting Y slope test proved that the joint had no cracks when the preheating temperature was over 100 C. The steel had a high anti Z cold cracking performance, and the fracture surface shrinkage rate of Z to crack resistance test was greater than that of the 35%. bolt test in preheating and not preheating. Under the heat condition, the strength of the coarse-grained region is greater than the minimum tensile strength of the steel. It shows that the coarse-grained region also has good cold cracking resistance, and SA738Gr.B has good weldability.
The special welding material for SA738Gr.B of low alloy steel was studied. The iron powder type welding rod E9018-G-H4 and ER90S-G welding wire were developed successfully. Through the experimental study, it was proved that the electrode has good technological properties and good mechanical properties when the content of iron powder is 15% and the ratio of calcium carbonate fluorite is about 1.6:1. The effect of alloy elements on the mechanical properties of the welding seam shows that with the increase of carbon equivalent, the tensile strength and yield strength of the deposited metal can significantly affect the low temperature impact toughness of the deposited metal. When the nickel content is about 1%, the toughness is higher at low temperature. The welding rod has been applied to the welding of the AP1000 steel shell. The amount of use has reached 320 tons.
The mechanical properties of the joint are studied on the basis of the weldability and welding material of the steel plate. The study shows that the welding line energy has a significant influence on the impact toughness of the joint. With the increase of the line energy, the appropriate process of the.SA738Gr.B steel plate is preheated and the small line energy is reduced with the increase of the line energy. In the process of heat treatment, there will be a change of recovery and recrystallization in the process of heat treatment. With the prolongation of the heat treatment time, the grain has a tendency to grow up, the carbide precipitates to the grain boundary, and the intragranular dislocation density decreases, resulting in the decrease of the impact toughness.
The field engineering practice shows that the welding materials developed and the welding technology determined according to the results of this study can meet the technical requirements of the SA738Gr.B nuclear safety shell, and the welding quality meets the requirements of ASME III and technical conditions, and it has obtained the approval of the domestic and foreign counterparts.
The dual phase steel is sensitive to the line energy, and the toughness and corrosion resistance of the heat affected zone are reduced. The toughness and corrosion resistance of the heat affected zone can be recovered completely by the solution treatment. It can even reach the degree of close to the parent material. In order to further study the effect of temperature on the double phase steel joint, the joints after the solution are at 500, 600, 700, 800, 900. The results show that the impact toughness and corrosion resistance increase first and then increase with the increase of aging temperature. The 700 C is the most sensitive temperature of S32101 double phase stainless steel welded joint,.S32l0l non rust joint,.S32l0l stainless steel joint carried out at 700 C, indicating that Cr2N is precipitated and grown in the crystal, resulting in two austenite of poor chromium. The root cause of plasticity, ductility reduction and corrosion resistance.
The field engineering practice shows that the welding materials developed and the welding technology determined according to the results of this study can meet the technical requirements of the AP1000 nuclear safety shell, and the welding quality meets the requirements of ASME III and technical conditions, and it has obtained the approval of the domestic and foreign counterparts.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG457.11

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