热轧Mn13耐磨钢的磨损性能及硬化行为研究

发布时间：2018-05-15 15:45

本文选题：热轧Mn13耐磨钢 + 滑动磨损　；参考：《中国矿业大学》2015年硕士论文

【摘要】：颚式破碎机颚板作为破碎机的核心部件,它受到撞击和物料冲刷的双重作用,工况多为中、高冲击载荷和循环变形与疲劳作用,磨损程度较高。铸造高锰钢的铸造缺陷和马氏体耐磨钢低韧性的缺点大大降低了颚板的工作效率。热轧工艺可在保证高塑韧性的同时有效解决受铸造工艺局限性带来的组织疏松、缩孔、晶粒粗大等缺陷的影响。本文以热轧奥氏体高锰耐磨钢(Mn13钢)为实验材料,针对破碎机复杂的工况条件,以滑动磨损、磨料磨损、冲击磨料磨损的形式开展磨损实验综合评价其耐磨性能,并利用扫描电镜、X射线衍射仪、透射电镜等,分析了磨损机理和硬化机制。滑动磨损试验表明,与B-Hard400钢和B-Hard500钢相比,除了高载荷干摩擦和低载荷煤泥粉的工况Mn13钢的耐磨性表现的更为优秀,干摩擦时磨损机理主要表现为犁沟和疲劳剥落磨损,以煤泥粉和石英砂为磨料时磨损机理主要表现为犁沟切削和凿削切割的破坏机制,高载时还存在煤泥粉的碾压粘着膜;磨料磨损试验表明,Mn13钢的耐磨性在以硬质颗粒(煤矸石、石英砂)为磨料的情况下较好,加工硬化效果明显,煤泥粉磨料磨损的机制表现为微观切削并伴随局部的疲劳剥落,以煤矸石为磨料的磨损机制为微观切削,伴随挤压剥落和局部区域的疲劳剥落,以石英砂为磨料的磨损机制则为典型的凿削磨损和微观切削。在冲击磨料磨损试验中,1-8J冲击功下Mn13钢的磨损量走势呈“M形”,在2J和5J时磨损量最大,4J和7J时磨损量最小,最佳冲击功工况为3.5-4.5J和6-7J。在2J、4J、5J和7J的冲击功下,随着冲击次数增多,磨损量逐渐增大。在中、高冲击功条件下Mn13钢的硬化层厚度可达3500μm以上,最高达6500μm。从磨损亚表层的金相组织中均可以观测到形变孪晶的存在,随着冲击功提高在局部晶粒内生长的孪晶密度增大。切削、塑变、凿削和疲劳剥落是Mn13钢冲击磨料磨损的主要机制,随着冲击功的提高加工硬化程度得到提升,切削痕变少疲劳剥落坑增多。在中冲击功的作用下,孪晶和位错的交互作用是主要的硬化机制,少量相变ε(hcp)起辅助作用;在高冲击功的作用下,主要硬化机制为高密度孪晶条带互相交割使奥氏体组织细化为微晶甚至纳米晶,碳化物析出、α(bcc)相变等起辅助硬化作用。
[Abstract]:Jaw crusher jaw plate, as the core component of the crusher, is affected by the double effects of impact and material scour. The working conditions are mostly medium, high impact load and cyclic deformation and fatigue, and the wear degree is high. The casting defects of the cast high manganese steel and the lack of the martensitic wear steel low toughness greatly reduce the working efficiency of the jaw plate. Hot rolling process At the same time, it can effectively solve the defects of loose tissue, shrinkage cavity and coarse grain caused by the limitation of casting process at the same time. In this paper, the hot rolled austenite high manganese wear-resistant steel (Mn13 steel) is used as the experimental material. In the case of the complicated working conditions of the crusher, the wear of sliding wear, abrasive wear and impact abrasive wear is carried out. The wear resistance was evaluated and the wear mechanism and hardening mechanism were analyzed by scanning electron microscope, X ray diffractometer and transmission electron microscope. The sliding wear test showed that compared with B-Hard400 steel and B-Hard500 steel, the wear resistance of Mn13 steel was better than that of high load dry friction and low load slime powder, and the dry friction grinding mill was used. The main damage mechanism is plough furrow and fatigue exfoliation wear. The wear mechanism of the slime powder and quartz sand is mainly manifested in the failure mechanism of furrow cutting and chisel cutting while the high load still exists the roller compacted adhesive film on the high load, and the abrasive wear test shows that the wear resistance of Mn13 steel is abrasive with hard particles (gangue and quartz sand). The mechanism of the work hardening is obvious. The mechanism of the abrasive wear of the pulverized coal powder is characterized by micro cutting and local fatigue peeling. The wear mechanism of the gangue as the abrasive wear mechanism is micro cutting, with the extrusion peeling and the fatigue exfoliation in the local area, and the wear mechanism of the quartz sand is the typical chisel wear and micro cutting. In the impact abrasive wear test, the wear of Mn13 steel under the impact of 1-8J impact is "M shape", the wear amount is the largest at 2J and 5J, the wear of 4J and 7J is the smallest. The optimum impact work condition is 3.5-4.5J and 6-7J. at 2J, 4J, 5J and the impact work, with the increase of the impact times. The thickness of the hardened layer is more than 3500 m. The deformation twin can be observed in the metallographic structure of the subsurface of the wear surface, which is up to 6500 m.. With the increase of impact work, the twin density increases in the local grain. The main mechanism of the abrasive wear of Mn13 steel is cutting, plastic deformation, chiseling and fatigue spalling. With the effect of impact work, the interaction of twin and dislocation is the main hardening mechanism, and a small amount of phase transition epsilon (HCP) plays an auxiliary role. Under the action of high impact work, the main hardening mechanism is that the high density twin strip intersections make the austenite microstructure refined. Microcrystalline or even nanocrystalline, carbide precipitates, and alpha (BCC) phase change plays an auxiliary hardening role.

【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG142.1

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