本文關(guān)鍵詞： 電渣重熔 調(diào)質(zhì)處理 組織結(jié)構(gòu) 力學性能 電化學行為　出處：《安徽工業(yè)大學》2016年碩士論文　論文類型：學位論文

【摘要】：目前30Cr Ni3MoV鋼被廣泛應用于石油行業(yè),一般用于制造壓裂泵、汽輪機等重要零件,然而石油開采難度越來越大,開采環(huán)境越來越惡劣,對石油機械用鋼的性能要求也越來越高。本文首先對比電渣30CrNi3MoV鋼和非電渣30CrNi3MoV鋼的在不同工藝下的純凈度,并利用兩次正火+調(diào)質(zhì)處理的熱處理工藝提高其力學性能,試圖實現(xiàn)以非電渣錠代替電渣錠的目的,降低生產(chǎn)成本,減少對環(huán)境的污染;研究Mn、Si含量對非電渣30CrNi3MoV鋼組織及性能的影響;利用極化曲線和電化學阻抗測試研究非電渣30CrNi3MoV鋼在不同濃度HCl中的電化學腐蝕特征,利用金相顯微鏡、掃描電鏡對非電渣30CrNi3MoV鋼的組織及銹層形貌進行表征分析。研究結(jié)果表明:電渣重熔對30CrNi3MoV鋼的純凈度的改善效果有限,電渣錠和非電渣錠中的S、P等雜質(zhì)元素含量很低,電渣重熔對30CrNi3MoV鋼中夾雜影響較小,兩種鋼中都只有少量(1級)的環(huán)狀氧化物夾雜,未發(fā)現(xiàn)其他類型夾雜。兩次正火工藝明顯細化30CrNi3MoV鋼的原奧氏體晶粒度,并改善其組織遺傳現(xiàn)象。通過調(diào)質(zhì)工藝后的電渣和非電渣重熔30CrNi3MoV鋼的調(diào)質(zhì)組織為回火索氏體,組織較細小。電渣鋼橫縱向晶粒都有輕微的晶粒大小不均勻現(xiàn)象。非電渣鋼的強度略高于電渣鋼,橫縱向力學性能比都≥95%,兩種鋼的力學性能指標都達到了規(guī)定要求,在冶煉工藝合理的前提下,并通過兩次正火+調(diào)質(zhì)處理的熱處理工藝后,以非電渣錠代替電渣錠是基本可行的。Mn含量從0.66%增加到1.05%時,對非電渣30CrNi3MoV鋼的晶粒度、調(diào)質(zhì)組織影響不大,Mn含量的提高減小了馬氏體束尺寸,細化淬火組織,對試驗鋼的抗拉強度、屈服強度、伸長率、斷面收縮率、硬度的影響很小,但會顯著降低試驗鋼的沖擊功,降低幅度為40%;Si含量從0.26%增加到0.7%對非電渣30CrNi3MoV鋼的晶粒度級別沒有影響,Si含量的提高降低了調(diào)質(zhì)組織中碳化物的數(shù)量;增加了淬火組織中板條馬氏體數(shù)目,減少了馬氏體束以及針狀馬氏體數(shù)目;當Si含量增加時,試驗鋼的抗拉強度σb、屈服強度σ0.2、硬度HB分別提高了15.9%、13%、12%。在5%HCl溶液中,整個腐蝕過程受陽極反應控制,當Mn含量提高時,非電渣30CrNi3MoV鋼的腐蝕電流密度Icorr增大,抗腐蝕性能下降,當Si含量提高時,試驗鋼的腐蝕電流密度Icorr降低,抗腐蝕性能提高。在10%HCl、15%HCl和20%HCl溶液中,陽極反應常數(shù)βa、腐蝕電流密度Icorr、銹層電阻Rr以及極化電阻Rs等參數(shù)的變化趨勢與5%HCl溶液中的基本一致。隨著HCl溶液濃度的增大,三種鋼的抗腐蝕性能均下降,陽極反應常數(shù)βa和腐蝕電流密度Icorr增大,溶液電阻Rs也隨之變小,試樣的銹層厚度增大,當溶液濃度達到15%時,銹層厚度達到最大。當Mn含量增加時,失重量增加,失重的突變發(fā)生時間提前;當Si含量增加時,失重量減小,失重的突變發(fā)生時間推遲。
[Abstract]:At present, 30Cr Ni3MoV steel is widely used in petroleum industry, generally used to manufacture fracturing pump, steam turbine and other important parts. However, oil extraction is becoming more and more difficult, and the mining environment is getting worse and worse. The performance requirements of petroleum mechanical steel are more and more high. Firstly, the purity of electroslag 30CrNi3MoV steel and non-electroslag 30CrNi3MoV steel under different processes is compared. The heat treatment process of twice normalizing and tempering is used to improve its mechanical properties. The purpose of replacing electroslag ingots with non-electric slag ingots is attempted to reduce the production cost and to reduce the pollution to the environment. The effect of Mn-Si content on the microstructure and properties of non-electroslag 30CrNi3MoV steel was studied. The electrochemical corrosion characteristics of non-electroslag 30CrNi3MoV steel in different concentrations of HCl were studied by polarization curve and electrochemical impedance test. The microstructure and rust layer morphology of non-electroslag 30CrNi3MoV steel were characterized by SEM. The results showed that the effect of electroslag remelting on the purity of 30CrNi3MoV steel was limited. The content of impurity elements such as Schion P in electroslag ingot and non-electroslag ingot is very low. The influence of electroslag remelting on inclusions in 30CrNi3MoV steel is small, and there is only a small amount of ring oxide inclusions in both steels. No other inclusions were found. The original austenite grain size of 30CrNi3MoV steel was obviously refined by twice normalizing process. The microstructure of 30CrNi3MoV steel after quenching and tempering is tempered with Soxhlet. The microstructure is smaller and the grain size is slightly uneven in the transverse and longitudinal grains of the electroslag steel. The strength of the non-electroslag steel is slightly higher than that of the electroslag steel, and the ratio of transverse and longitudinal mechanical properties is 鈮，

本文編號：1444335