Mo-Fe-B系堆焊合金组织与性能的研究

发布时间：2018-01-19 06:12

本文关键词： Mo-Fe-B系合金 TIG堆焊 Mo_2FeB_2 组织硬度耐磨性　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：Mo-Fe-B系堆焊合金具有优异的力学性能、耐磨性能和耐腐蚀性能,可用于在高温高压、承受较大载荷及氧化、腐蚀等苛刻工况条件下运行工件的表面堆焊。本文设计并制备了 Mo-Fe-B系堆焊合金粉块,采用TIG堆焊工艺在Q235母材上制备堆焊合金层,采用光学显微镜、扫描电镜(SEM)、X射线衍射、显微硬度计、洛氏硬度计和磨损试验等方法,研究了 Mo、B、N加入量对堆焊合金组织和性能的影响;设计并制备不同B源的堆焊合金粉块,探究不同B源对堆焊层组织与性能的影响。Mo加入量为30%和25%时,堆焊合金中除了主要的Mo2FeB2硬质相和Fe-Cr之外,还有少量的Cr2B3、MoB等二元硼化物。Mo加入量为30%时,堆焊合金中有大量的长条状硬质相,Mo加入量为25%时,硬质相的数量有所减少,形态则变为面积较小的方形以及不规则多边形。Mo加入量低于20%时,堆焊合金中无明显的硬质相生成。堆焊合金的硬质相和共晶组织中,均含有Mo、Fe、Cr,Mo富集在硬质相中,Fe富集在共晶组织中,而Cr的分布比较均匀。Mo加入量为25%时,堆焊合金的硬度达到最大值,其微观硬度和宏观硬度分别为1053HV0.5、58.6HRC,增加或降低Mo含量,硬度均有所降低。随着Mo加入量的减少,堆焊合金的耐磨性能变差。增加B的加入量,可以改善脱渣性和焊缝成型。在Mo加入量为15%不变的情况下,当B加入量为6%时,堆焊合金中出现了 Mo2FeB2硬质相,且随着B加入量的增加,堆焊合金中硬质相的数量明显增多。随着B加入量的增加,堆焊合金的显微硬度和宏观硬度都随之提高,B加入量为10%时,显微硬度为1266HV0.5,宏观硬度为70.1HRC。堆焊合金的耐磨性能随着B加入量的增加而提高。合金粉块中N加入量为0%时,堆焊合金中的硬质相呈方形及长条状;N加入量为1%时,硬质相形态为较小的方形;当N加入量为2%时,硬质相呈不规则的形状且数量明显减少。没有加入N时,堆焊合金中的物相除了 Fe-Cr、Mo2FeB2之外,还有MoB、Cr2B3等二元硼化物,N加入合金粉块之后,堆焊合金中的N主要以Cr2N的形式存在。堆焊合金的微观硬度和宏观硬度,都随着N加入量的增加而减小,耐磨性变差。研究了合金粉块中作为B源的硼铁粉、硼粉以及钼铁硼粉三种原材料对堆焊合金组织性能的影响。结果表明,硼铁粉和钼铁硼粉作为B源的堆焊合金中有大量的三元硼化物硬质相形成,加入硼铁粉的堆焊合金主要由复合硼化物Mo2FeB2、y-FeCr和二元硼化物的共晶组织组成,硬质相大多呈长条状,其显微硬度和宏观硬度分别为830HV0.5、54.5HRC;加入钼铁硼粉的堆焊合金硬质相多呈方形,数量多于加硼铁粉的,其显微硬度和宏观硬度分别为1136HV0.5和56.8HRC。加硼粉的堆焊合金主要由Fe-Cr,σ-FeMoCr及少量的Mo2FeB2组成,其显微硬度和宏观硬度较低,分别为368HV0.5、37HRC。
[Abstract]:Mo-Fe-B surfacing alloys have excellent mechanical properties, wear resistance and corrosion resistance, can be used in high temperature and high pressure, large load and oxidation. In this paper, Mo-Fe-B surfacing alloy blocks were designed and prepared, and TIG surfacing technology was used to prepare surfacing alloy layer on Q235 base metal. Mohlb was studied by means of optical microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), microhardness meter, Rockwell hardness tester and wear test. Effect of N addition on microstructure and properties of surfacing alloy; The effect of different B sources on the microstructure and properties of the surfacing layer was investigated. The addition of Mo was 30% and 25% respectively. In addition to the main Mo2FeB2 hard phase and Fe-Cr, there is also a small amount of Cr _ 2B _ 3O _ (MoB) and other binary boride. Mo when the addition amount is 30. When there are a large number of long stripe hard phase Mo in the surfacing alloy, the number of hard phase decreases when the addition amount of Mo is 25. On the other hand, when the shape is small square and irregular polygon. Mo content is lower than 20, there is no obvious hard phase in the surfacing alloy. Mo is found in both hard phase and eutectic structure of surfacing alloy. Fe and Fe in hard phase are enriched in eutectic structure, and the hardness of surfacing alloy reaches the maximum when the distribution of Cr is uniform and the addition of Mo is 25. The microhardness and macroscopic hardness were 1053HV0.5C58.6HRCrespectively, increasing or decreasing the content of Mo, the hardness decreased, and with the increase of Mo content, the hardness decreased. The wear resistance of the surfacing alloy becomes worse. With the addition of B, the slagging and weld forming can be improved. When the amount of Mo is 15%, the addition of B is 6. The hard phase of Mo2FeB2 appeared in the surfacing alloy, and with the increase of B content, the number of hard phase in the surfacing alloy increased obviously, and with the increase of the content of B addition. The microhardness and macroscopic hardness of the surfacing alloy are increased with the addition of 10 B, the microhardness is 1266HV0.5. The hardness of surfacing alloy is 70.1 HRC. The wear resistance of the surfacing alloy increases with the increase of B content. When the N content in the alloy powder is 0, the hard phase in the surfacing alloy is square and long. When N addition is 1, the hard phase is a small square. When N content is 2, the hard phase is irregular in shape and the number is obviously reduced. Without N addition, there is MoB in the surfacing alloy in addition to Fe-Cr-Mo _ 2FeB2. After the addition of Cr2B3 and other binary boride N into the alloy powder, the N in the surfacing alloy mainly exists in the form of Cr2N. The microhardness and macroscopic hardness of the surfacing alloy are obtained. The effect of three raw materials, iron boron powder, boron powder and molybdenum ferroboron powder, on the microstructure and properties of surfacing alloy was studied. There are a large number of ternary boride hard phases in the surfacing alloy of iron boron powder and ferromolybdenum boron powder as B source. The surfacing alloy with iron boron powder is mainly composed of compound boride Mo2FeB2. The eutectic structure of y-FeCr and binary boride, the hard phase is mostly long stripe, its microhardness and macroscopic hardness are 830HV0.5 / 54.5HRC, respectively. The hard phase of surfacing alloy with ferro-molybdenum and boron powder is square, and the quantity is more than that of iron powder with boron. The microhardness and macroscopic hardness are 1136HV0.5 and 56.8 HRC, respectively. The surfacing alloys with boron powder mainly consist of Fe-Cr, 蟽 -FeMoCr and a small amount of Mo2FeB2. Its microhardness and macroscopic hardness are lower, which are 368HV0.5 and 37HRC, respectively.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG455

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