电工钢板材斜刃横剪边缘损伤机理研究

发布时间：2018-01-23 02:19

本文关键词： 电工钢斜刃横剪剪切间隙边缘损伤晶粒尺寸　出处：《广东工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文基于斜刃横剪加工实验,研究了不同工艺条件对电工钢板材剪切断面毛刺、边缘硬化、磁性能等损伤规律,发现对0.23mm取向电工钢,当相对间隙(间隙板厚比c/t%)在4.3%~6.5%,断面质量相对较好,边缘损伤程度也较低。由于其晶粒沿轧制方向取向的特殊性,磁性能表现出各向异性,越靠近轧制方向磁性能越好。对无取向电工钢,0.35mm板在相对间隙4.3%~5.7%,剪切带和断裂带高度变化幅度较小,损伤程度相对较低。对0.5mm和0.65mm板,除在较小间隙外,在适当的间隙范围5%~7%,也能获得相对较好的剪切断面,边缘硬化,磁性能损耗均较小。上述四种板厚的最大硬化影响区达600μm,且硬化不均匀,截面和板面两个方向的硬化影响深度基本一致,另外随剪切条数增加,剪切边缘损伤区域增多,磁性能越恶化,而剪切速度对断面质量影响不大。研究发现随剪切间隙变化,各板材的剪切断面形貌、毛刺、剪切边缘硬化以及磁性能损伤之间具有较一致的对应规律,建立了不同间隙剪切后宏观毛刺与微观损伤之间的相关性。对于取向和无取向电工钢,其区别不仅在于晶粒取向有无方向性,更重要的是不同板厚以及晶粒尺寸决定了其剪切性能的差异,板厚越薄,其晶粒尺寸越大,相应的抗剪能力越弱,也需考虑不同剪切间隙对变形的影响。利用XRD对不同间隙剪切样品进行织构分析表明,在相对较小和较大间隙时织构成分的含量对磁性能均不利,而处在中间的适当间隙时则表现出较好的织构质量,通过主成分分析进一步说明了随相对间隙变化,铁损、矫顽力与织构含量的变化存在可靠的线性关系。根据不同板厚的微观组织观察,引入尺寸效应因子λ=t/d,考虑不同板厚与晶粒尺寸的比值下材料变形的区别,进而建立侧向间隙与晶粒尺寸的关系模型,结合多晶材料的塑性变形理论分析了c/d1、c/d≈1、c/d1三种情况下材料变形的区别,进一步通过剪切边缘微观组织以及不同侧隙下剪切的受力情况分析,对上述模型进行验证,发现断面的塌角、剪切带、断裂带和毛刺的形成与材料的晶粒尺寸以及侧向间隙、板厚关系密切,通过c/d以及t/d的比值可以发现不同比值下,材料发生了不同的力学行为,从而导致了材料产生了不同的宏观断面,相应地影响了组织变形的程度,进而决定了剪切边缘硬化及磁性能损伤的程度。以剪切边缘磁畴结构观察为基础,通过纳米压痕法研究残余应力对磁畴结构的影响,发现剪切边缘磁畴改变与残余应力的分布具有较好的对应关系,残余应力不仅对磁畴宽度产生影响,更为重要的是改变了磁畴的形态。依据剪切边缘微观组织观察,建立了组织变形与取向变化关系模型,通过XRD检测分析,发现剪切在很大程度上影响了晶粒取向的改变,进一步研究发现晶粒取向随变形量的衍变主要由形核位置的改变而引起的,在不同的侧隙条件下形核位置的改变以及应力的共同作用引起了组织晶粒取向、织构的衍变,进而影响了磁性能。
[Abstract]:The oblique edge shear processing based on experiments of hardened edge of different technological conditions on the electrical steel sheet shearing section, burr, magnetic properties and other damage law, found on 0.23mm oriented electrical steel, when the relative gap (the gap thickness ratio c/t%) in the 4.3%~6.5% section, quality is relatively good, edge damage degree is also lower due. The particularity of the grain orientation along the rolling direction, magnetic properties exhibit anisotropy, the more close to the rolling direction better. Magnetic properties of non oriented electrical steel plate, 0.35mm in the relative gap 4.3%~5.7%, shear zone and fracture zone height variation amplitude is smaller, the damage degree is relatively low. The 0.5mm and 0.65mm board, except in small clearance, clearance in the appropriate scope of the 5%~7%, also can obtain relatively good edge shearing section, hardening, magnetic loss was small. The largest area of the four kinds of hardening effect of plate thickness up to 600 m, and the hardening is not uniform, and the cross section The surface hardening effect of the two directions of the depth is consistent with the shear number also increased, the shear edge damage area increases and the magnetic properties worse, while the shear velocity has little effect on the quality of cross section. The study found that changes with the shear gap, shear fracture morphology, the sheet shearing edge burrs, hardening and magnetic properties with corresponding rules more consistent damage, the correlation between macro and micro burr damage is established. For different gap shear oriented and non oriented electrical steel, the distinction is not only there is no direction of grain orientation, more important is the different thickness and grain size determines the difference between the shear performance of the plate thickness is thin, the increase of the grain size, the corresponding shear capacity is weak, also need to consider the effect of shear deformation. The gap of different gap shear sample texture analysis indicated that the use of XRD, in a relatively small And a larger gap when the texture components content on the magnetic properties were negative, while in the middle of the proper clearance when the show texture of good quality, through principal component analysis further illustrates the changes with the relative gap of iron loss, there are linear relationship between the change of coercivity and reliable texture content. Based on the observation of the microstructure of different plate the thickness, size effect factor =t/d, considering the difference between the material deformation ratio of different thickness and grain size, and then establish the relationship model of lateral clearance and grain size, combined with the theory of plastic deformation of c/d1 polycrystalline materials, c/d = 1, the difference between material deformation of c/d1 under three conditions through further analysis of microstructure and shear edge stress under different shear clearance, to verify the model, found that section of the collapse angle, shear zone, fault zone and the formation of grain size and material of the burr Inch plate thickness and lateral clearance, close by c/d and the ratio of t/d can be found in different ratio, the mechanical behavior of different materials, resulting in material produced macrosection different, the corresponding impact on the organization degree of deformation, and then determine the cutting edge hardening and magnetic properties of the extent of the damage. In order to observe the shear edge domain structure based on nano indentation method by residual stress effect on domain structure, distribution of shear edge domain change and residual stress has a good corresponding relationship, the residual stress not only affects the domain width, more important is to change the domain morphology based on the shear. The edge of the microstructure observation, established tissue deformation and orientation change relation model, through XRD analysis, we find that the shear effect of grain orientation change to a great extent, further research It is found that the evolution of grain orientation with deformation is mainly caused by the change of nucleation location. Under different backlash conditions, the change of nucleation location and the interaction of stress cause the evolution of grain orientation and texture, and further affect the magnetic properties.

【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG142.1

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