【作者】 张杰；

【导师】 梅瑞斌；

【作者基本信息】 东北大学 ， 材料工程（专业学位）， 2018， 硕士

【摘要】 硅钢是一种含碳量很低的硅铁软磁合金,已被广泛应用在电气元件的芯部部件上。由于轧制过程形成的各向异性使硅钢板在后续二次成形,特别是在冲裁过程中发现毛刺较大且有时冲裁圆形度不够等问题,一定程度上降低了硅钢片生产效率和质量。为此,本文以典型的冷轧无取向硅钢50W800为研究对象,利用组织性能测试和有限元数值分析手段研究其各向异性性能及其对冲裁过程的影响规律。本文主要研究内容及结论如下:(1)针对冷轧无取向硅钢薄带设计加工三种不同取向角度(0°、45°、90°)的样品,0°方向为沿轧制方向,90°方向为法线方向,45°方向与轧制方向在同一平面内成45°夹角。探索其在不同应变速率(0.003s-1、0.006s-1、0.012s-1)下的力学性能和流变应力曲线。发现试样在同一取样方向不同应变速率下,随着应变速率的微增,其屈服强度σs和抗拉强度σb均呈微升趋势,但相差不大,断后延伸率δ则呈下降趋势。从同一应变速率,不同取样方向的工程应力-应变曲线看出,45°方向上的σs和σb明显高于其它两个方向,0°方向次之,.90°方向的最小,即冷轧无取向硅钢板带具有一定的各向异性。(2)基于单向拉伸实验数据,通过非线性回归和线性拟合,构建无取向硅钢片50W800在0°、45°、90°方向上的本构方程,为冲裁加工过程中材料变形和断裂失效分析提供理论基础,并为冲裁有限元模拟提供材料硬化模型。(3)通过观察分析不同方向和不同应变速率下的拉伸试样断口形貌发现:无取向硅钢片50W800的拉伸断口表现为以韧性断裂为主,韧性和脆性特征共存的现象。在取样方向相同时,应变速率越小,韧性断裂特征越明显,应变速率增大时,韧窝数量减少,解理台阶和解理面增多,在同一应变速率下,45°方向韧窝较其它两个方向少且深度较浅,90°方向韧窝数量多且较深,0°方向韧窝和解理面数量居两者中间。(4)提出了数值模拟圆形度和毛刺评判方法,基于50W800的有限元冲裁过程结果发现:模具冲裁间隙越大,所产生的冲裁毛刺也就越大。通过对不同冲裁间隙的模拟对比,发现12%t为硅钢片的最佳冲裁间隙。当模具间隙一定时,模具圆角越大,毛刺也会增大,通过模拟几种不同模具圆角,发现4%t冲裁毛刺较少,采用冲裁间隙12%t和4%t的圆角时,冲裁件毛刺最少且圆形度较好,尺寸和形状精度最高。更多还原

【Abstract】 Silicon steel is a kind of low carbon ferrosilicon magnetic alloy,which has been widely used in the core components of electrical components.Because of the anisotropy of rolling silicon steel in process,the problems of large burr and sometimes insufficient roundness were found in the subsequent two forming process,especially in the blanking process.This reduced the efficiency of production and quality of silicon steel sheet to some extent.Therefore,taking the typical cold-rolled non-oriented silicon steel 50W800 as the research object,the anisotropic properties and the influence rule of the blanking process are studied by means of microstructure and performance test and finite element numerical analysis.The main contents and conclusions of this paper are as follows:(1)Select the cold-rolled non-oriented silicon steel strip,three samples with different angles from different orientations(0°,45°,90°)are processed.The 0° direction is along the rolling direction,the 90° direction is the normal direction,and the 45 ° direction is 45°to normal direction on the rolling-normal direction surface.The mechanical properties and stress-strain curves under different strain rates(0.003s-1,0.006s-1,0.012s-1)are explored.Based on the non-oriented silicon steel sheet 50W800 tensile at room temperature,it is found that the sample at different direction and same strain rate,when the strain rate increased,the yield strength and tensile strength are increased,while the elongation decreased.From the same strain rate and different sampling direction’s engineering stress-strain curve,tensile strength and yield strength in the direction of 45° are significantly higher than other two directions,tensile strength and yield strength of 90° is the smallest.This means cold-rolled non oriented silicon steel sheets with anisotropy.(2)Based on uniaxial tensile test data,the constitutive equations of 50W800 non-oriented silicon steel sheet at 0°,45°and 90°directions were respectively obtained by non-linear regression and linear fitting.This equation provides a theoretical basis for the analysis of material deformation and fracture failure in blanking process,and offers a material hardening model for the finite element simulation of blanking.(3)By observing and analyzing the fracture morphology of tensile specimens under different directions and strain rates,it is found that the tensile fracture morphology of non-oriented silicon steel sheet 50W800 is consist of ductile,toughness and brittleness.In the same direction,dimple is relatively small and uniform,with the increase of strain rate,the number of dimples decrease,cleavage step and cleavage surface increased significantly.While in the same strain rate,the dimple in 45°direction shallow less than other two directions,and dimples are more and deeper in 90°direction,the number of dimples and cleavage planes of 0°in the middle.(4)The evaluation method of numerical simulation in roundness and burr is put forward.Based on 50W800,the simulation results of finite element blanking process show that the larger the blanking clearance is,the larger the punching burr will be.Through the simulation of different blanking gaps,it is found that 12%t is the best blanking gap for silicon steel sheet.When the die clearance is stable,die fillet increases,the burr will also increase.Through the simulation of several different die fillets,4%t die fillet is the best.When adopting the blanking clearance 12%t and 4%t die fillet,blanking burr is minimum and roundness is better,the size and shape will be the highest precision.更多还原