【摘要】：磨煤輥是煤粉制備的重要設(shè)備,其耐磨性受到廣泛關(guān)注。采用藥芯焊絲明弧自保護(hù)堆焊修復(fù)或制造磨煤輥已成為一種經(jīng)濟(jì)且可靠的提高磨煤輥使用壽命的方法。本文以鐵基高鉻明弧堆焊合金為研究對(duì)象,通過調(diào)節(jié)藥芯焊絲成分,試圖研制能滿足磨煤輥堆焊實(shí)際應(yīng)用要求的自保護(hù)耐磨堆焊藥芯焊絲。采用藥芯焊絲自保護(hù)明弧焊方法在Q235A基體上制備堆焊合金,借助光學(xué)顯微鏡、掃描電子顯微鏡及其附屬電子能譜儀、X射線衍射儀,觀察分析其顯微組織,并通過宏觀硬度測(cè)試和濕砂磨粒磨損試驗(yàn)研究其性能。首先,研究了不同碳含量的過共晶高鉻明弧堆焊合金的顯微組織及性能,結(jié)果表明,高鉻明弧堆焊合金組織由初生碳化物M7C3和共晶基體組成,隨著合金中碳含量的增加,初生碳化物M7C3數(shù)量增多,尺寸變大,組織中碳化物體積分?jǐn)?shù)顯著增加,基體數(shù)量減少,共晶碳化物連續(xù)性增強(qiáng)對(duì)基體割裂作用加劇,致使合金韌性降低。碳含量對(duì)高鉻明弧堆焊合金硬度及耐磨性影響顯著,隨著碳含量的增加,硬度升高,耐磨性反而下降。當(dāng)碳含量較高時(shí),微觀剝落成為高鉻堆焊合金耐磨性下降的主要原因,提高高鉻堆焊合金的耐磨性應(yīng)當(dāng)注重其韌性的改善。其次,分別向藥芯焊絲中加入不同含量的硼鐵、釩鐵、鎢鐵、鈦鐵和鈮鐵,研究了合金元素硼、鎢、釩、鈦和鈮對(duì)高鉻明弧堆焊合金組織和性能的影響。結(jié)果表明:硼能使共晶點(diǎn)左移,促進(jìn)初生碳化物M7C3的生成,且組織中生成高硬度的硼化物或碳硼化合物,顯著提高堆焊合金硬度,但過多的硼使合金脆性增加,耐磨性下降;釩對(duì)碳原子具有團(tuán)聚效應(yīng),可改變?nèi)垠w碳濃度分布,增加初生M7C3相體積分?jǐn)?shù),抑制脆性組織生成,適量V具有顯著改善明弧堆焊合金耐磨性的作用;鎢能使高鉻合金共晶點(diǎn)左移,增加初生碳化物M7C3體積分?jǐn)?shù),減少共晶碳化物的數(shù)量,使基體組織中奧氏體增加,有利于合金韌性的提高;鈦的加入使熔體優(yōu)先析出TiC,TiC充當(dāng)初生M7C3和γ-Fe的異質(zhì)形核核心,提高它們的形核率,起到細(xì)化初生相和基體組織的作用,有利于合金韌性的提高,但過多的鈦會(huì)使剩余熔體貧碳,反而抑制初生M7C3的生成;高鉻合金中的鈮全部以NbC的形式存在,NbC彌散分布,可以細(xì)化晶粒,增加合金韌性,對(duì)提高堆焊合金硬度和耐磨性有利。
[Abstract]:Grinding roller is an important equipment for the preparation of pulverized coal, and its wear resistance is widely concerned. It has become an economical and reliable method to improve the service life of grinding coal roller by using flux cored wire self-protection surfacing welding to repair or manufacture grinding coal roller. By adjusting the composition of flux-cored wire, a self-protective and wear-resistant surfacing flux-cored wire can be developed to meet the requirements of the practical application of the surfacing welding of grinding coal roll, taking the iron-base high-chromium bright arc surfacing alloy as the research object in this paper. The surfacing alloy was prepared on Q235A substrate by self-shielded open arc welding with flux-cored wire. The microstructure was observed and analyzed by means of optical microscope, scanning electron microscope and its subsidiary electron energy spectrometer, X-ray diffractometer. The properties were studied by macrohardness test and wet sand abrasive wear test. Firstly, the microstructure and properties of hypereutectic high chromium open arc surfacing alloy with different carbon content were studied. The results show that the microstructure of high chromium open arc surfacing alloy is composed of primary carbides M7C3 and eutectic matrix, and with the increase of carbon content in the alloy, The number and size of primary carbides M7C3 increased, the volume fraction of carbides in microstructure increased significantly, the number of matrix decreased, and the effect of eutectic carbide continuity on matrix cleavage increased, resulting in the decrease of alloy toughness. The effect of carbon content on hardness and wear resistance of high chromium bright arc surfacing alloy is significant. With the increase of carbon content, hardness increases and wear resistance decreases. When the carbon content is high, the micro-exfoliation becomes the main reason for the decrease of wear resistance of the high chromium surfacing alloy, and the improvement of the wear resistance of the high chromium surfacing alloy should pay attention to the improvement of its toughness. Secondly, the effects of the alloying elements boron, tungsten, vanadium, titanium and niobium on the microstructure and properties of high chromium bright arc surfacing alloys were studied by adding different amounts of ferric boron, ferrovanadium, tungsten, vanadium, titanium and niobium into the flux-cored wire respectively. The results show that boron can make the eutectic point shift to the left, promote the formation of primary carbides M7C3, and form high hardness boride or carboboron compounds in the microstructure, which can significantly increase the hardness of surfacing alloy, but excessive boron can increase the brittleness of the alloy and decrease its wear resistance. Vanadium has agglomeration effect on carbon atoms, which can change the carbon concentration distribution of melt, increase the volume fraction of primary M7C3 phase and inhibit the formation of brittle microstructure. Tungsten can make eutectic point of high chromium alloy move to the left, increase M7C3 volume fraction of primary carbides, reduce the amount of eutectic carbides, increase austenite in matrix structure, and improve the toughness of alloy. The addition of titanium makes the melt precipitate TiC,TiC as the heterogeneous nucleation core of primary M7C3 and 緯-Fe, increases their nucleation rate, refines the primary phase and matrix structure, and improves the toughness of the alloy. However, too much titanium can make the residual melt carbon poor and inhibit the formation of primary M7C3. All niobium in high chromium alloy exists in the form of NbC and NbC dispersion distribution can refine the grain and increase the toughness of the alloy. It is beneficial to improve the hardness and wear resistance of the surfacing alloy.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG422.3

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 牛沖;;堆焊技術(shù)在立式磨磨輥制造中的應(yīng)用淺析[J];價(jià)值工程;2012年29期

，

本文編號(hào)：2340712