高强高韧性耐磨钢板的冲击磨料磨损性能研究

发布时间：2018-08-02 09:23

【摘要】：磨损是材料失效的主要形式之一。80%上的机械材料消耗于磨损,上的装备恶性事故起因于过渡的磨损和润滑失效。因此,开发高性能的耐磨钢铁材料,对减少材料磨损过程中的损失、提高机械装备的使用寿命有着至关重要的意义。低合金耐磨钢板作为一种重要的耐磨钢铁材料,合金含量低、综合性能良好、生产灵活方便及价格便宜等持点,被广泛的应用于工程机械、矿山机械及冶金机械等设备的生产制造。本文主要以Cr-Ni-Mo、Mo-Ti-B高强韧性马氏体钢、不同形变强化的高氮奥氏体钢为研究对象,通过对实验材料最大变形区域垂直切表面金相组织、显微硬度与磨损面的SEM、TEM组织及EBSD大小角晶界取向分布特征等进行研究,综合讨论了材料强化硬化及磨损失效机理。(1)对Cr-Ni-Mo、Mo-Ti-B马氏体钢进行冲击磨损实验,并对磨损亚表面硬化程度进行表征。结果表明:随着冲击时间的增加,在2.5J的冲击功作用下,Mo-Ti-B钢耐磨性逐步下降,在3.5J的冲击功作用下,Cr-Ni-Mo钢耐磨性比Mo-Ti-B钢的耐磨性要好。在低中冲击载荷作用下,Cr-Ni-Mo钢在较硬硬质磨料(白刚玉)磨损量较大,而在高冲击载荷下其磨损量相当。亚表层的硬度明显高于基体的硬度,随亚表层深度增加,加工硬化程度逐渐降低。(2)通过对材料基体以及2.5J冲击时间为2h的冲击磨损试验EBSD研究分析,实验结果表明:Cr-Ni-Mo钢的大小角度晶界冲击前后分别63.6%、36.4%,47.4%、52.6%;Mo-Ti-B钢的大小角度晶界冲击前后分别59.1%、40.9%,61.2%、38.8%。Cr-Ni-Mo钢小角度密度晶界提高导致材料强度不断提高,使材料的耐磨性提高。而Mo-Ti-B钢的大小角度晶界变化不明显。(3)在3.5J冲击功作用下,Cr-Ni-Mo钢耐磨性呈现先降低后增加的趋势,对亚表面最大变形区进行SEM、TEM观察,实验结果表明:基体组织呈现低温回火特性,马氏体组织逐步分解成为铁素体基体以及大量的尺寸在500nm的硬质碳化物,通过TEM衍射花样标定,析出相为ε-碳化物,碳化物在基体组织中起到骨架支撑作用,减少基体与磨料之间的接触,从而提高材料的耐磨性能。而Mo-Ti-B钢在2.5J冲击功,冲击2h时,在磨损表面区域马氏体基体快速分解为铁素体与渗碳体,随着磨损时间的进一步增加,碳化物不断的长大,与基体脱离共格关系,碳化物与基体之间连接薄弱,有利于微裂纹的形成,降低材料的耐磨性。(4)针对不同形变强化的高氮奥氏体钢的冲击磨损硬化机制进行讨论,主要从切表面的显微硬度变化,金相组织的变化,以及磨损面的磨损形貌等方面讨论。研究结果表明:在1.5J、2.5J、3.5J冲击载荷后,10mm高氮钢亚表面硬化范围在438.45HV～497.09HV,硬化深度在1400μm左右;而50mm高氮钢412HV～494HV硬化深度在1000μm左右。随着冲击能量的提高加工硬化程度得到提升,切削痕、犁沟变少疲劳剥落坑变多。EBSD统计结果表明:10mm高氮钢经过3.5J冲击载荷后,10mm高氮钢小角度晶界由59.4%增加到73.7%,50mm高氮钢小角度晶界由68.6%增加到73.6%,通过位错缠结起到位错强化或晶界强化作用,耐磨性均有提升的趋势。50mm高氮钢基体大角度晶界所占比例相对于10mm高氮钢减小,材料的韧性有所降低。
[Abstract]:Wear is one of the main forms of material failure. The mechanical material on.80% is consumed by wear and wear. The malignant accident on the equipment is due to the transition wear and lubrication failure. Therefore, the development of high performance wear-resistant steel materials is of vital importance to reducing the loss of material wear and improving the service life of mechanical equipment. As an important wear-resistant steel material, the wear-resistant steel plate is widely used in the production of engineering machinery, mining machinery and metallurgical machinery, such as low alloy content, good comprehensive performance, convenient production and cheap price and so on. This paper mainly uses Cr-Ni-Mo, Mo-Ti-B high strength and toughness martensitic steel, and high nitrogen with different deformation intensification. Austenitic steel is the research object. Through the study of the microstructure of the vertical cutting surface in the maximum deformation area of the experimental material, the microhardness and the wear surface SEM, TEM structure and the distribution characteristics of the grain boundary orientation distribution of the EBSD size angle, the mechanism of material hardening and wear failure is discussed comprehensively. (1) the impact wear on Cr-Ni-Mo and Mo-Ti-B martensitic steel is carried out. The results showed that with the increase of impact time, the wear resistance of Mo-Ti-B steel decreased gradually with the impact time of 2.5J, and the wear resistance of Cr-Ni-Mo steel was better than that of Mo-Ti-B steel under the impact of 3.5J. Under the impact of low medium impact load, Cr-Ni-Mo steel was hard and hard abrasive. The wear amount of white corundum is larger, and its wear amount is equal under high impact load. The hardness of subsurface is obviously higher than that of matrix, and the degree of work hardening gradually decreases with the increase of subsurface depth. (2) the analysis of the impact wear of the material matrix and the impact time of 2.5J is 2H. The experimental results show that the large Cr-Ni-Mo steel is large. The small angle grain boundary before and after impact is 63.6%, 36.4%, 47.4%, 52.6% respectively. The grain boundary of Mo-Ti-B steel is 59.1%, 40.9%, 61.2%, and the grain boundary of 38.8%.Cr-Ni-Mo steel is increased to increase the material strength and improve the wear resistance of the material, and the grain boundary of the Mo-Ti-B steel is not obvious. (3) the impact work of 3.5J is made. In use, the wear resistance of Cr-Ni-Mo steel appears to be reduced first and then increased, and the maximum deformation area of the subsurface is SEM and TEM. The experimental results show that the matrix microstructure presents low temperature tempering, martensitic structure gradually decomposes into ferrite matrix and a large number of hard carbides in 500nm, demarcated by TEM diffraction pattern and precipitated. For the epsilon carbide, carbides play a skeleton support in the matrix structure, reducing the contact between the matrix and the abrasive, thus improving the wear resistance of the material. While the Mo-Ti-B steel has the impact work of 2.5J and the impact of 2h, the martensitic matrix is rapidly decomposed into ferrite and carburized body in the martensitic matrix on the worn surface, and with the further increase of the wear time, carbonization is made. The relationship between the substrate and the matrix is constantly growing, and the connection between the carbide and the matrix is weak. It is beneficial to the formation of micro cracks and the wear resistance of the material. (4) the impact and wear hardening mechanism of the high nitrogen austenite steel with different deformation intensification is discussed, mainly from the change of microhardness of the surface of the cutting surface, the change of metallographic structure, and the wear and tear. The results show that the subsurface hardening range of 10mm high nitrogen steel is in the range of 438.45HV to 497.09HV and the hardening depth is about 1400 mu m after the impact load of 1.5J, 2.5J and 3.5J, while the hardened depth of 50mm high nitrogen steel 412HV to 494HV is about 1000 mu m. With the increase of the impact energy, the hardening degree of the high nitrogen steel is improved and the cutting marks are improved. The.EBSD statistical results show that the low angle grain boundary of high nitrogen steel in 10mm is increased from 59.4% to 73.7% after 3.5J impact load, and the small angle grain boundary of 50mm high nitrogen steel increases from 68.6% to 73.6%. The effect of dislocation strengthening or grain boundary intensification through dislocation entanglement, the tendency of wear resistance to enhance.50mm high nitrogen The proportion of large angle grain boundary of steel matrix decreases with the decrease of 10mm high nitrogen steel, and the toughness of material decreases.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG142.1

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