本文選題：焊縫成形　切入點：晶間腐蝕　出處：《蘭州交通大學(xué)》2015年碩士論文

【摘要】：奧氏體不銹鋼因具有優(yōu)良的力學(xué)性能和耐腐蝕性能,以及突出的焊接性能和生物相容性,在核島工業(yè)、航空航天、生物醫(yī)學(xué)等諸多領(lǐng)域中得到了廣泛的應(yīng)用。然而,在工程應(yīng)用方面,由于受傳統(tǒng)焊接方法在控制線能量方面的局限性,使得奧氏體不銹鋼焊接接頭極易出現(xiàn)因晶界貧鉻而導(dǎo)致的晶間腐蝕,從而顯著降低接頭的耐蝕性能。超窄間隙焊接方法(UNGW)由于側(cè)壁間距不大于6mm,極大地降低了焊接線能量,在改善奧氏體不銹鋼焊接性及接頭耐晶間腐蝕具有獨特的優(yōu)勢。論文采用Φ2.0mm焊絲,利用超細顆粒焊劑熔化后形成的熔渣殼對焊接電弧的約束作用,進行了一系列超窄間隙焊接1Cr18Ni9Ti奧氏體不銹鋼的試驗,并分別研究了焊接電流和電弧電壓對焊縫成形規(guī)律、焊縫組織以及接頭耐晶間腐蝕性能的影響。試驗結(jié)果表明,能夠獲得成形良好焊縫的電弧電壓與焊接電流的匹配區(qū)間分別為25V~33V和210A~320A,而在這個范圍之外的其它參數(shù)匹配情況下,焊縫成形情況分別為“側(cè)壁熔合不良”和“電弧攀升”。觀察不同線能量雙道焊接頭的組織表明,當(dāng)線能量為0.84kJ/mm時,第一道焊縫的組織為均勻等軸晶,第二道焊縫的組織為方向性很強的粗大柱狀晶;當(dāng)線能量為1.13 kJ/mm時,第一道焊縫的組織同樣為等軸晶,而第二道焊縫的柱狀晶組織發(fā)生細化,且夾雜有少量近似等軸晶的晶粒;當(dāng)線能量為1.28 kJ/mm時,第一道焊縫組織仍為等軸晶組織,但第二道焊縫的組織由柱狀晶向等軸晶過渡。掃描電鏡下觀察接頭的浸泡腐蝕微觀形貌表明,隨著焊接線能量的增大,試樣焊縫區(qū)的腐蝕由不均勻腐蝕向均勻腐蝕轉(zhuǎn)變;而相比之下,不同試樣焊縫區(qū)兩側(cè)的熱影響過熱區(qū)的腐蝕形貌無太大差異。計算接頭腐蝕速率表明,試驗所得接頭,其耐蝕性優(yōu)于母材。綜上所述,在匹配合理的焊接參數(shù)下,采用Φ2.0mm焊絲在超細顆粒焊劑約束電弧超窄間隙焊接1Cr18Ni9Ti奧氏體不銹鋼可獲得焊縫成形良好、耐晶間腐蝕和點蝕性能優(yōu)良的超窄間隙焊接接頭。
[Abstract]:Austenitic stainless steel has been widely used in many fields such as nuclear island industry, aerospace, biomedicine and so on because of its excellent mechanical and corrosion resistance, outstanding welding properties and biocompatibility. In engineering application, due to the limitation of conventional welding method in control line energy, austenitic stainless steel welded joints are prone to intergranular corrosion caused by chromium deficiency in grain boundary. Therefore, the corrosion resistance of the joints is significantly reduced. The ultra-narrow gap welding method UNGW has greatly reduced the welding line energy because the side wall spacing is not greater than 6 mm. In order to improve the weldability of austenitic stainless steel and the intergranular corrosion resistance of the joints, 桅 2.0mm wire is used in this paper, and the slag shell formed by the melting of superfine particle flux is used to restrain the welding arc. A series of experiments on ultra-narrow gap welding of 1Cr18Ni9Ti austenitic stainless steel were carried out, and the effects of welding current and arc voltage on weld formation, weld microstructure and intergranular corrosion resistance of joints were studied respectively. The matching ranges of arc voltage and welding current for well-formed weld are 25V~33V and 210A320A, respectively. The weld formation conditions are respectively "bad side wall fusion" and "arc climbing". The microstructure of the double pass welding joint with different wire energy is observed. When the line energy is 0.84kJ/mm, the structure of the first weld is uniform equiaxed crystal. The structure of the second weld is a coarse columnar crystal with strong directionality, and when the linear energy is 1. 13 kJ/mm, the structure of the first weld is equiaxed, while the columnar structure of the second weld is refined, with a small amount of grains approximately equiaxed. When the line energy is 1. 28 kJ/mm, the structure of the first weld is still equiaxed, but the structure of the second weld is transferred from columnar to equiaxed. The corrosion of the weld zone of the specimen changed from non-uniform corrosion to uniform corrosion, but the corrosion morphology of the heat-affected superheated zone on both sides of the weld zone of different specimens was not much different. The calculation of the corrosion rate of the joints showed that the joints obtained from the tests showed that, The corrosion resistance of the stainless steel is superior to that of the base metal. To sum up, under the reasonable welding parameters, 桅 2.0mm wire can be used to weld 1Cr18Ni9Ti austenitic stainless steel in ultra-narrow gap of ultra-narrow arc confined by superfine particle flux. Ultra narrow gap welded joints with excellent resistance to intergranular corrosion and pitting.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG457.11

【共引文獻】

相關(guān)期刊論文 前4條

1 房菲;李靜媛;王一德;;18Mn18Cr高氮鋼析出相特征及形成機制[J];北京科技大學(xué)學(xué)報;2014年06期

2 房菲;李靜媛;王一德;;含氮不銹鋼凝固模式及顯微組織研究[J];北京科技大學(xué)學(xué)報;2014年11期

3 陳雨來;房菲;李靜媛;王一德;;C含量對高氮奧氏體不銹鋼18Mn18CrN析出行為的影響[J];材料熱處理學(xué)報;2015年09期

4 Yu-ping LANG;Hua-peng QU;Hai-tao CHEN;Yu-qing WENG;;Research Progress and Development Tendency of Nitrogen-alloyed Austenitic Stainless Steels[J];Journal of Iron and Steel Research(International);2015年02期

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本文編號：1680161