【作者】 王鑫；

【导师】 赵成志； 孙福民；

【作者基本信息】 哈尔滨工程大学 ， 工程硕士（专业学位）， 2014， 硕士

【摘要】 对于矿业来说,材料磨损带来的经济损失一直是非常巨大的,仅球磨机衬板,每年因磨损造成的损失,就可高达20万吨。开发新型耐磨钢材料,降低矿业设备磨损消耗对提高矿业生产效率、节省采矿成本及拓展采矿空间都具有重要意义。本文根据矿山湿磨工况,自主设计了一种新型合金耐磨钢,利用thermo-calc热力学软件模拟计算设计材料的相组成及合金元素的分布,并采用熔炼铸造方法对该设计材料进行了制备;对材料的热处理工艺进行了设计和优化,通过硬度测试、冲击试验、拉伸试验等力学性能分析手段,以及金相观察、XRD分析、SEM及能谱分析等组织分析手段来研究不同热处理工艺对组织性能的分析;选优化后的部分工艺,对其耐磨性能及耐蚀性进行探究,分析不同组织对磨损、腐蚀性能的影响。研究发现:本材料由于合金元素的加入,使珠光体转变的孕育期大幅延长,在保温时间较短的退火过程中,均未生成珠光体,当随炉冷却时,过冷奥氏体转变为马氏体,使材料的硬度不降反升;只有采用不发生相变的软化退火工艺,才能有效的降低材料的硬度,改善切削性能。淬火时,加热温度越高,材料中析出相溶入奥氏体中的效果越好,但获得的马氏体板条更加粗大。本材料由于含有能够稳定奥氏体的合金元素,因此在等温淬火时,还能够获得粒状组织。采用低温回火能使第二相析出,发生二次硬化,提高材料的强度,同时可以改善材料的韧性。本材料的化学成分为:C 0.305%,Cr 1.504%,Cu 0.450%,Mo 0.479%,Mn 1.111%,Ni 0.944%,Si 0.695%, Nb 0.045%, V 0.092%。通过力学性能结果比较分析,优化后的热处理工艺是:700℃退火5h,900℃油淬+300℃回火,此时,材料的硬度值达到51.6HRC,抗拉强度为1600MPa,冲击韧性达到57.4J/cm2。此时,材料的组织为回火马氏体+析出第二相,这种组织的耐磨性能比经等温淬火获得粒状组织的材料的耐磨性要高出近3倍;同时,其耐蚀性能也达到最佳。更多还原

【Abstract】 In mining industry, large economic losses were always caused by the wear of the materials.For example, only for the liner materials of the mill, which would lose up to 20w tons due to the wear and tear every year. In this case,it is becoming more and more important to develop the wear resistant materials for reducing the wear consumption to improve mining productivity, save cost and expand the space of the mining.In the background of wet mill working condition, a new type of alloy wear resistant steel has been designed independently for wet milling. Firstly, the thermodynamic software which can simulate the phase composition of the material and the distribution of the alloy elements was used to design the composition of the new steel in order to understand the existent phase of the material at different temperature. And then, this new type material was prepared by melting and casting methods. The heat treatment process of the material was also designed and optimized. The impact of the different heat treatment process on the structure and mechanical properties such as hardness, impact testing and tensile testing of the designed materials were analyzed by metallographic observation, XRD analysis, SEM and EDS analysis. Finally, the effects of the different microstructure on wear resistant and corrosion resistant of the materials were studied with the part of the optimized materials.The results show that the pearlite transformation incubation period is extended greatly as the addition of the alloying elements. During the annealing process of shorter holding time, no pearlite was discovered. And when materials cooling with furnace temperature, the super-cooled austenitic will transform into the martensite that makes the hardness of the materials rise, not fall. Only the softening annealing without the phase transition can reduce the hardness of the material effectively and improve the machinability of the material. In the quenching process, the precipitation phase dissolve into the austenitic becomes better with the heating temperature rising while the lath martensite becomes bulky. As the doping of the alloy elements to stablelize the austenitic,the granular structure will be obtained during the isothermal quenching. The second phase will be precipitated and secondary hardening will occur in low temperature tempering to improve strength and toughness of the materias.The designed materials contain the elements of C 0.305%, Cr 1.504%, Cu 0.450%, Mo 0.479%,Mn 1.111%,Ni 0.944%,Si 0.695%,Nb 0.045% and V 0.092%. Comparing the consequence of the mechanical property, the optimized heat treatment process was determined to be 700℃ annealing, 900℃ oil quenching and 300℃ tempering. The hardness can be up to 51.6HRC, the tensile strength is 1600MPa, the impact toughness is 57.4J/cm2. The structure of the material is the tempered martensite with second phase. The wear resistant of this structure is better than the one of the granular structure which is obtained by the isothermal quenching, and the corrosion of this structure is also better.更多还原