Abstract Submerged arc welding (SAW) is one of the important industrial welding processes for heavy industries which include ship building and steel industries. The transient temperature distribution during the welding process has a significant influence on the heat affected zone width, microstructure formation, residual stresses, distortion, and hence on the fatigue behaviour of the welded structures. To accurately determine the transient temperature distribution, the exact shape of the heat source distribution needs to be considered. Machine vision can be a unique method for determination of such transient temperature distribution. In this paper, a machine vision system is developed to determine the transient shape of isotherm of submerged arc welded plates. It is based on infrared imaging to capture and extract the temperature history of the welding process. The transient temperature distribution is observed to be egg shape. The shape of isotherm is analyzed and validated with the experimental data acquired for a wide range of process parameters. These comparisons showed close agreement. The extracted data from the proposed machine vision system is used as the input information for various investigations, such as maximum temperature, isotherm generation, cooling rate plots and image segmentation studies. The developed method is a contactless method. It not only eliminates the possible errors encountered in contact measurement methods, but also provides a user friendly interface and accurate results in less time, and hence significantly reduces the experimental time. This method demonstrated its successful application for submerged arc welding, and furthermore it can be applied for the estimation of transient temperature field in other manufacturing processes.

中文翻译：

---

基于红外成像的机器视觉系统确定埋弧焊中等温线的瞬态形状

摘要 埋弧焊（SAW）是重工业包括造船和钢铁工业的重要工业焊接工艺之一。焊接过程中的瞬态温度分布对热影响区的宽度、微观结构的形成、残余应力、变形等具有重要影响，进而对焊接结构的疲劳行为产生重要影响。为了准确确定瞬态温度分布，需要考虑热源分布的确切形状。机器视觉可以成为确定这种瞬态温度分布的独特方法。在本文中，开发了一种机器视觉系统来确定埋弧焊板等温线的瞬态形状。它基于红外成像来捕捉和提取焊接过程的温度历史。观察到瞬态温度分布呈蛋形。对等温线的形状进行了分析，并使用针对各种工艺参数获得的实​​验数据进行了验证。这些比较表明非常一致。从所提出的机器视觉系统中提取的数据用作各种调查的输入信息，例如最高温度、等温线生成、冷却速率图和图像分割研究。所开发的方法是一种非接触式方法。它不仅消除了接触测量方法中可能遇到的错误，而且在更短的时间内提供了一个用户友好的界面和准确的结果，从而大大减少了实验时间。