Ultrasonic impact treatment (UIT) combined with high-energy electropulsing (EP) was applied to D36 low-carbon steel with three different electrical regimes. Submicron crystalline was obtained on the superficial region after the treatment due to continuous dynamic recrystallization. The cementite experienced strain-induced decomposition and precipitation. The microstructure is significantly determined by the current density and temperature. A strengthened layer with a maximum hardness of 285 HV was obtained in EP-UIT, in comparison with the hardness of 227 HV resulted from UIT solely. Alongside with high hardness, the strengthened layer extended to a remarkable depth of nearly 2 mm due to acoustic softening, electroplasticity and thermal softening engaged simultaneously. A 3-μm oxide layer in average consisting of magnetite and hematite formed on the treated surface. Joule heat and athermal effect of EP are the factors inducing these phenomena.

中文翻译：

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D36钢在电脉冲和热辅助的超声冲击下的组织演变和再结晶。

超声冲击处理（UIT）结合高能脉冲（EP）被应用于具有三种不同电学方案的D36低碳钢。处理后，由于连续动态重结晶，在表层区域获得了亚微米级晶体。渗碳体经历了应变诱导的分解和沉淀。微观结构很大程度上取决于电流密度和温度。与仅由UIT产生的227 HV的硬度相比，在EP-UIT中获得了最大硬度为285 HV的增强层。除了高硬度外，由于同时进行了声软化，电塑性和热软化处理，增强层延伸至近2 mm的显着深度。在处理过的表面上平均形成一个3μm的氧化层，由磁铁矿和赤铁矿组成。EP的焦耳热和无热效应是引起这些现象的因素。