强流脉冲电子束处理50BA及30SiMn2MoVA高强钢的显微组织及性能研究

发布时间：2018-01-15 07:23

本文关键词：强流脉冲电子束处理50BA及30SiMn2MoVA高强钢的显微组织及性能研究　出处：《重庆理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：高强钢(High Strength Steel)具有优良的综合力学性能,广泛应用于军事、民用领域。随着零件的服役环境变得复杂化、多样化、恶劣化,对材料的性能提出了更高的要求。目前,传统化学热处理方法存在着能量利用率低、生产效率低、工件变形量大、污染环境等缺点,表面涂层技术又存在着结合力差的缺点,而强流脉冲电子束(HCPEB)作为一种新型的高能、高效的表面改性技术以其自身独特的优势,规避了传统表面改性技术的缺陷,能够达到提高零件表面强度、耐磨性和耐蚀性能的目的。本论文分别以50BA和30SiMn2MoVA高强钢为基材,利用强流脉冲电子束设备以不同的脉冲次数对试样表面进行重熔处理,主要研究了改性前后试样的表截面显微形貌、微观组织结构的变化规律以及耐磨性和耐蚀性等力学性能的变化情况。研究结果表明:(1)经HCPEB处理后,试样表面经过熔体喷发,产生了火山坑状的“熔坑”。50BA高强钢试样表面的“熔坑”呈弥散分布,30SiMn2MoVA高强钢试样表面的“熔坑”呈网状结构,随着脉冲次数的增加,熔坑的数量逐渐减少,试样表面微区逐渐变得平滑,50BA高强钢试样表面熔坑尺寸先增大后变小,30SiMn2MoVA高强钢试样表面熔坑尺寸变小,网状结构逐渐消失,熔坑逐渐呈现出独立分布状态。(2)50BA和30SiMn2MoVA高强钢试样表面都发生了相变,产生了马氏体和残余奥氏体,随着脉冲次数的增加,马氏体的含量相对减少,残余奥氏体的含量相对增加。快速加热与凝固使试样表层晶粒细化,第二相颗粒尺寸变小,分布更为均匀。(3)经HCPEB处理后,试样表面显微硬度得到提高,其中50BA高强钢经50次脉冲处理后,表面硬度最大,相比于原始试样提高了20.9%;30SiMn2MoVA高强钢经30次脉冲处理后,表面硬度相比于原始试样提高了39.6%。试样表面组织由马氏体和残余奥氏体组成,这种软硬复合相的存在以及晶粒细化都有助于提高试样表面的耐磨性。试样磨损量随脉冲次数的增加而降低,相对耐磨性至少提高1倍,其中30和50次脉冲处理后试样的相对耐性相对于原始试样都提高了2倍。在耐蚀性方面,随着脉冲轰击次数的增加,试样表面腐蚀电流密度逐渐降低,腐蚀电位逐渐升高,使腐蚀速率降低,腐蚀倾向性减小,其中50BA高强钢试样表面经50次脉冲处理后试样表面的耐蚀性能最好,腐蚀电流密度降低了43.5%,30SiMn2MoVA高强钢试样表面经30次脉冲处理后试样表面的耐蚀性能最好,腐蚀电流密度降低了48.8%。
[Abstract]:High strength steel Strength steel has excellent comprehensive mechanical properties and is widely used in military and civil fields. With the service environment of parts becomes more and more complicated and diversified. At present, the traditional chemical heat treatment methods have the disadvantages of low energy utilization, low production efficiency, large deformation of workpiece, pollution of environment and so on. As a new type of high energy and high efficiency surface modification technology HCPEB has its own unique advantages. Avoiding the defects of the traditional surface modification technology, it can improve the surface strength, wear resistance and corrosion resistance of the parts. In this paper, 50BA and 30SiMn2MoVA high strength steel are used as the substrates, respectively. High current pulsed electron beam equipment was used to remelt the surface of the sample with different pulse times. The microstructure of the surface section of the sample before and after modification was studied. The change of microstructure, wear resistance and corrosion resistance, the results show that after HCPEB treatment, the surface of the sample is ejected by melt. The "melting pit" on the surface of the high-strength steel sample with volcanic crater shape. 50BA is distributed diffusely. The "melting pit" of the specimen surface of 30SiMn2MoVA high strength steel has a network structure. With the increase of pulse number, the number of melting pits decreases gradually, and the surface microzone becomes smooth and the surface size of 50BA high strength steel first increases and then becomes smaller. The size of the melting pit on the surface of 30SiMn2MoVA high strength steel becomes smaller and the mesh structure gradually disappears. The melting pits gradually show an independent distribution state. Both the surface of the specimens of 30SiMn2MoVA and 30SiMn2MoVA have been transformed, resulting in martensite and retained austenite, with the increase of pulse times. The content of martensite decreases and the content of residual austenite increases. The grain size of the surface layer of the sample is refined and the size of the second phase grain is smaller by rapid heating and solidification. After HCPEB treatment, the surface microhardness of 50BA high strength steel was increased, and the surface hardness of 50BA high strength steel was the largest after 50 pulse treatment. Compared with the original sample, 20.9% was increased. After 30 pulse treatment, the surface hardness of 30SiMn2MoVA high strength steel is 39.6 higher than that of the original sample. The surface microstructure of 30SiMn2MoVA steel is composed of martensite and retained austenite. The existence of the soft and hard composite phase and grain refinement can improve the wear resistance of the sample surface. The wear rate of the sample decreases with the increase of pulse number, and the relative wear resistance increases by at least one time. The relative resistance of the samples after 30 and 50 pulse treatments was increased by 2 times compared with the original samples. In terms of corrosion resistance, the corrosion current density of the samples gradually decreased with the increase of pulse bombardment times. The corrosion potential increases gradually, the corrosion rate decreases and the corrosion tendency decreases. The surface of 50BA high strength steel is treated with 50 pulses and the corrosion resistance is the best. The corrosion current density is reduced by 43.5% and the corrosion resistance of the sample surface treated with 30 pulses is the best, and the corrosion current density is reduced by 48.8%.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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