We present the results of metallographic investigations of the structure and microhardness and the results of the bench tests of the threads of tubings made of steels of the strength class D after finishing electromechanical surface quenching in pairs with commercial couplings.

中文翻译：

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机电表面淬火后油管螺纹的组织和显微硬度

我们展示了结构和显微硬度的金相研究结果，以及强度等级 D 钢制成的管材在与商用联轴器成对完成机电表面淬火后的螺纹台架试验结果。