Correlation Among the Input Thermal Parameters and Thermography Measurements Data of the Resistance Seam Welding

Abstract Resistance Seam Welding (RSEW) is commonly used in continuous steel processing for joining steel coils. Experimental studies focused on the welding process quality controls are justified by their wide application and influence on the performance of steelmaking processes. The present study focuses on the continuous annealing line welding process using as sample, a low carbon steel (0.07%C) with 0.21 mm thickness. The work proposes a correlation of thermal input, electric current parameter and thermogram monitoring during RSEW procedures. A methodology was developed to determine the real thermal profiles values by means of association of the thermograms with the sample emissivity curve. Three heat input levels were used, 3.64 J.mm-1, 5.09 J.mm-1, and 6.38 J.mm-1, respectively, for typical C-Mn steel. The thermal welding profile obtained experimentally exhibited linear correlation coefficients (R) of 0.99 with the electric current welding parameter and (R) of 0.99 with the calculated thermal input, respectively. The welds metallurgical characterizations results, expressed through the ductility and welds nuggets analysis, were conducted to correlate the welds quality with the welding thermal input. The Erichsen cupping test showed that the higher the thermal input corresponds to higher ductility of the welds. Nevertheless, the heat input of 5.09 J.mm-1 indicated better-balanced properties: ductility, weld nugget discontinuity, nugget size, and no expulsion of the melt material.摘要：电阻缝焊（Resistance Seam Welding，RSEW）广泛应用于钢材连续加工工序中，用于钢卷的对接连接。鉴于其应用范围广泛且对炼钢工序性能具有显著影响，针对该焊接过程的质量控制开展实验研究具备充分的合理性。本研究以厚度为0.21mm的低碳钢（碳含量0.07%）为试样，聚焦于连续退火生产线的焊接工艺。本工作旨在建立电阻缝焊过程中热输入、电流参数与热像图监测之间的关联关系。研究开发了一种方法，通过将热像图与试样发射率曲线相结合，以确定真实的焊接热分布曲线数值。针对典型碳锰钢，分别采用了3.64 J·mm⁻¹、5.09 J·mm⁻¹与6.38 J·mm⁻¹三种热输入水平。实验测得的焊接热分布曲线与焊接电流参数的线性相关系数R为0.99，与计算得到的热输入的线性相关系数R同样为0.99。研究通过延展性分析与焊接熔核分析开展焊缝冶金特性表征，以建立焊缝质量与焊接热输入之间的关联。埃里克森杯突试验结果表明，热输入越高，焊缝的延展性越好。然而，热输入为5.09 J·mm⁻¹时，焊缝的综合性能更为均衡：其延展性、熔核不连续性、熔核尺寸均表现优异，且未发生熔液喷溅现象。