本文選題：輥壓機(jī)　切入點：堆焊層　出處：《吉林大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：水泥產(chǎn)業(yè)是國民經(jīng)濟(jì)的基礎(chǔ)，而輥壓機(jī)是水泥生產(chǎn)礦石破碎系統(tǒng)和粉磨系統(tǒng)的關(guān)鍵設(shè)備。在實際工況中，輥壓機(jī)處在高磨損和高循環(huán)壓力下，輥面不僅存在磨粒磨損和摩擦磨損，同時伴隨有疲勞現(xiàn)象，最終導(dǎo)致輥面疲勞磨損失效甚至出現(xiàn)大塊剝落，故研究輥壓機(jī)輥面耐磨堆焊層的抗疲勞性能具有實際意義。 本文使用目前輥壓機(jī)常用的三種耐磨堆焊層藥芯焊絲和一種過渡層藥芯焊絲，采用熔化極自保護(hù)焊接方法在45鋼板上堆焊，分別分析這四種堆焊層的成分和微觀組織；用堆焊試板制備六種疲勞試樣，分別為三種不帶過渡層和三種帶有過渡層的疲勞試樣，采用自行設(shè)計的疲勞試驗機(jī)進(jìn)行疲勞試驗，對比三種不帶過渡層時耐磨堆焊層的抗疲勞性能差異及都帶有渡層時的抗疲勞性能差異，分析過渡層對抗疲勞性能的影響及其作用機(jī)制，最后分析疲勞試樣斷口形貌。 采用三種不同耐磨堆焊層藥芯焊絲獲得的堆焊層金屬分別為：含鈮合金鋼，其微觀組織以馬氏體和殘余奧氏體為主，還有大量NbC彌散分布在堆焊層里，其硬度較高，塑韌性相對較好；含鈮高鉻合金鑄鐵，其堆焊層下部為亞共晶組織，中部以共晶組織為主，上部為過共晶組織，也有NbC彌散整個堆焊層，硬度高，塑韌性較差；過共晶高鉻合金鑄鐵，，其堆焊層上部和中部為過共晶組織，下部以共晶組織為主，其硬度更高，塑韌性也更差。過渡層藥芯焊絲Cr和Mn含量高，堆焊層為奧氏體鋼，塑性和韌性較好。 試驗發(fā)現(xiàn)沒有過渡層的三種耐磨堆焊層金屬疲勞裂紋萌生階段差別不大，而裂紋擴(kuò)展階段差別較大；而帶有過渡層的三種耐磨堆焊層疲勞裂紋萌生階段差別大，而裂紋擴(kuò)展階段差別不大。含鈮合金鋼耐磨堆焊層抗疲勞性能最佳，母材裂紋擴(kuò)展到過渡層與耐磨層界面時停止擴(kuò)展，隨著循環(huán)應(yīng)力的加載，界面出現(xiàn)新裂紋后快速擴(kuò)展通過耐磨層；其次是含鈮高鉻合金鑄鐵耐磨堆焊層，最差的是過共晶高鉻合金鑄鐵耐磨堆焊層，母材裂紋都直接擴(kuò)展通過兩者的過渡層和耐磨層，并且都在耐磨層產(chǎn)生新裂紋，在過共晶高鉻合金鑄鐵的耐磨層和過渡層熔合區(qū)還有剝離裂紋產(chǎn)生。 過渡層使母材與耐磨層結(jié)合良好，可以有效的延長疲勞裂紋萌生階段，同時由于其塑性較好，當(dāng)母材裂紋擴(kuò)展到母材與過渡層界面時，裂紋擴(kuò)展路徑由縱向轉(zhuǎn)變?yōu)闄M向，從而提高疲勞強(qiáng)度。疲勞試樣斷口SEM分析可知，在裂紋擴(kuò)展區(qū)內(nèi)，有河流狀的疲勞花紋出現(xiàn)，略帶弧形，有較為規(guī)則的間距，與疲勞裂紋擴(kuò)展方向垂直。
[Abstract]:The cement industry is the foundation of the national economy, and the roller press is the key equipment for the crushing system and grinding system of cement production ore. There is not only abrasive wear and friction wear on the roll surface, but also fatigue phenomenon, which leads to the fatigue wear failure of the roll surface and even the appearance of the bulk spalling. Therefore, it is of practical significance to study the fatigue resistance of the wear-resistant surfacing layer on the roll surface of the roller press. In this paper, three kinds of wear-resistant surfacing flux-cored wire and one transition layer flux-cored wire are used to surfacing 45 steel plate. The composition and microstructure of the four surfacing layers are analyzed respectively. Six kinds of fatigue specimens were prepared by surfacing welding test plate. They were three kinds of fatigue samples without transition layer and three kinds with transition layer. Fatigue tests were carried out by self-designed fatigue testing machine. The difference of fatigue resistance of three kinds of wear-resistant surfacing layers without transition layer and the difference of fatigue resistance with crossing layer are compared. The influence of transition layer on fatigue resistance and its mechanism are analyzed. Finally, the fracture morphology of fatigue specimen is analyzed. The surfacing metals obtained by using three kinds of flux-cored wire with different wear-resistant surfacing layer are: niobium alloy steel, its microstructure is mainly martensite and retained austenite, and a large number of NbC dispersed in surfacing layer, its hardness is higher. The high chromium alloy cast iron containing niobium has hypoeutectic structure in the lower part, eutectic structure in the middle, hypereutectic structure in the upper part and NbC dispersion in the whole surfacing layer with high hardness and poor ductility. Hypereutectic high chromium alloy cast iron has hypereutectic structure in the upper and middle part of the surfacing layer and eutectic structure in the lower part of the cast iron. Its hardness is higher and its ductility is worse. The flux-cored wire of transition layer has high Cr and mn contents, and the surfacing layer is austenitic steel. Good ductility and toughness. The results show that the fatigue crack initiation stage of the three wear-resistant surfacing layers without transition layer is not different, but the crack propagation stage is quite different, while the fatigue crack initiation stage of the three wear-resistant surfacing layers with transition layer is different greatly. The fatigue resistance of the wear-resistant surfacing layer of niobium alloy steel is the best. When the base metal crack extends to the interface between the transition layer and the wear-resistant layer, it stops to propagate, and with the loading of cyclic stress, The wear resistant overlay of high chromium alloy cast iron containing niobium is the second, the worst is hypereutectic high chromium cast iron, and the base metal crack extends directly through the transition layer and wear resistant layer of both. New cracks were found in the wear resistant layer and exfoliated cracks in the fusion zone of the hypereutectic high chromium alloy cast iron and in the fusion zone of the transition layer. The transition layer makes the base metal and wear-resistant layer combine well, which can effectively prolong the fatigue crack initiation stage. At the same time, because of its good plasticity, when the base metal crack extends to the interface between the base metal and the transition layer, the crack growth path changes from longitudinal to transverse. In order to improve fatigue strength, SEM analysis of fracture surface of fatigue specimen shows that there are fluvial fatigue patterns, arc shape, regular spacing and perpendicular to the direction of fatigue crack propagation in the crack growth zone.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG455

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