Abstract

A process for obtaining semifinished products in the form of pipes made of copper alloys for electrical purposes by means of screw rolling is proposed. The results of experimental piercing and rolling of tube samples made of Cu–0.75Cr alloy billets with a diameter of 45 mm are presented. The samples, 43.5 × 10.0 mm in size, obtained after piercing with the use of a two-roll screw rolling mill, have exact geometrical dimensions: the deviation of the outer diameter at the front end is less than 1%, that at the rear end is less 2.4%, the relative nonuniformity of pipe wall thickness at the front end amounts to 0.3–0.5%, and that at the rear ranges within 0.5–1.0%. The pierced pipe samples have been rolled by using a three-roll minimill for radial-shear rolling (RSR) with a different total reduction level; the samples have been obtained with an outer diameter of 30, 25, and 18 mm. The reduction process has been analyzed from the standpoint of stability and deformation of the mouth of pipe. In the case of a 30% relative reduction of the outer diameter, the rolling without a mandrel is accompanied by an increase in the wall thickness. The deviations of the inner diameter are within permissible limits. The experiments performed for obtaining samples based on the Cu–0.75Cr alloy by means of screw piercing and reduction using an RSR mill show that this technique could be implemented in industry. At the same time, in order to obtain a quality product, it is necessary to more exactly determine the deformation parameters (deformation level and reduction mode). Different variants for the heat treatment (HT) of the pipe samples and the effect of the HT mode exerted on the electrical conductivity and hardness are considered. After piercing, the samples exhibited a conductivity of 59.3% IACS. The maximum electrical conductivity of 76.7% IACS has been obtained for the samples after quenching from a temperature of 1020°C and aging at 450°C for 3 h. The results of this work show that it is fundamentally possible to obtain semifinished products based on copper alloys for electrical purposes by means of screw rolling.

中文翻译：

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通过螺旋轧制获得电气用铜合金空心半成品

摘要

提出了一种通过螺旋轧制获得用于电气目的的由铜合金制成的管道形式的半成品的方法，该管道用于电气目的。介绍了直径45 mm的由Cu–0.75Cr合金坯料制成的管样品的实验性穿孔和轧制结果。使用两辊螺旋轧机穿孔后获得的尺寸为43.5×10.0 mm的样品具有精确的几何尺寸：前端的外径偏差小于后端的1％末端小于2.4％，前端的壁厚相对不均匀度为0.3-0.5％，而后端的相对不均匀度在0.5-1.0％之内。使用三辊小型轧机对穿孔的钢管样品进行轧制，该轧机的总压下量不同，但径向剪切轧制（RSR）。获得的样品的外径分别为30、25和18 mm。从管嘴的稳定性和变形的角度分析了压下过程。在外径相对减小30％的情况下，无心轴的轧制伴随壁厚的增加。内径偏差在允许的范围内。通过使用RSR轧机通过螺钉穿孔和还原获得基于Cu–0.75Cr合金的样品而进行的实验表明，该技术可以在工业中实施。同时，为了获得高质量的产品，有必要更精确地确定变形参数（变形水平和减小模式）。考虑了管道样品的热处理（HT）的不同变体以及HT模式对电导率和硬度的影响。穿刺后，样品的电导率为59.3％IACS。从1020°C的温度淬火并在450°C的温度下老化3小时后，样品的最大电导率达到了76.7％IACS。这项工作的结果表明，从根本上有可能通过螺旋轧制获得用于电气目的的基于铜合金的半成品。