Steel in Translation Pub Date : 2021-08-16 , DOI: 10.3103/s0967091221040021 N. G. Dudkina 1 , V. N. Arisova 1
Abstract
The results of complex studies on the structure, microhardness and depth of the hardened surface layer of 40Kh grade steel formed using electromechanical treatment with the dynamic application of a deforming force (EMT under impact) are shown. Investigations have been carried out using the methods of optical microscopy, XRD structural analysis, and microhardness measurement. The method of the electromechanical treatment with a dynamic force impact consists in a simultaneous transmission of electric current pulses and deforming force through the contact zone between a tool and a part. As a result of thermal impact with different current densities (j = 100, 300, 600 A/mm2), hardened layer segments with different sizes and different structural compositions are formed on the steel surface within cross-section. The analysis of structural and phase transformations in the surface layer of 40Kh grade steel subjected to electromechanical treatment indicates the formation of a specific white layer structure. The structure and properties of this layer are close to the metal amorphous state with maximum hardness HV = 8.0–8.5 GPa. As the distance from the surface increases, a transient zone is formed behind the segment of the white layer that does not have a needle structure inherent in martensite. With increasing current density under the impact the electromechanical treatment, the hardening depth exhibits a four-to-five-fold increase together with a simultaneous increase in the heterogeneity of strength properties, with the microstress level increasing by 25%. The experimental data obtained for the structural state, microhardness and depth of the surface layer of 40Kh grade steel show that the electromechanical treatment under the dynamic (impact) application of deforming forces causes much more profound transformations in the steel structure as compared with the traditional static EMT. According to electromechanical treatment under impact, results show that the intensity of the thermal-and-force action on the steel surface layer increases, which makes it possible to control the formation of the structural and phase states of 40Kh grade steel.
中文翻译:
40Kh钢在动力冲击下机电处理后的表层
摘要
显示了对 40Kh 级钢的硬化表面层的结构、显微硬度和深度的复杂研究结果,该表面层使用机电处理形成,动态施加变形力(冲击下的 EMT)。已经使用光学显微镜、XRD 结构分析和显微硬度测量的方法进行了研究。具有动态力冲击的机电处理方法包括通过工具和零件之间的接触区同时传输电流脉冲和变形力。由于不同电流密度的热冲击 ( j = 100, 300, 600 A/mm 2),在截面内的钢材表面形成不同尺寸和不同结构成分的硬化层段。经过机电处理的 40Kh 级钢表层的结构和相变分析表明形成了特定的白色层结构。该层的结构和性能接近具有最大硬度HV的金属非晶态= 8.0–8.5 GPa。随着距表面距离的增加,在不具有马氏体固有的针状结构的白色层段后面形成一个过渡区。随着机电处理冲击下电流密度的增加,硬化深度增加四到五倍,同时强度性能的不均匀性增加,微应力水平增加25%。40Kh级钢的组织状态、显微硬度和表层深度的实验数据表明,与传统的静态变形力相比,在动态(冲击)作用下的机电处理使钢结构发生更深刻的转变。急诊室。根据冲击下的机电处理,