The thermal efficiency of arc welding influences the cooling rate, peak temperature, and microstructures of a weld, which affects the material properties of the welded joint. This work quantifies the uncertainty of thermal efficiency measurements on gas metal arc welds using low (2.5 kW) and high (9.5 kW) arc powers. In order to understand the effect of calorimeter parameters on the measured efficiency, a two-factor, two-level full factorial design was carried out for each arc power condition. In this study, the factors are flow rate (2 l/min and 5 l/min) and plate thickness (0.25 in. [6.35 mm] and 0.375 in. [9.53 mm]). The results show that the uncertainty in the thermal efficiency measurements increases when both higher flow rates and plate thickness are used. Moreover, the use of a thick plate causes the heat transfer regime to change, increasing the cooling rate and decreasing the observed thermal efficiency. Uncertainty is also influenced by the metal transfer mode during welding.

中文翻译：

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短路和喷雾传输方式下焊接时水流热量计的不确定度分析

电弧焊的热效率会影响冷却速度，峰值温度和焊缝的微观结构，从而影响焊接接头的材料性能。这项工作量化了使用低（2.5 kW）和高（9.5 kW）电弧功率的气体金属电弧焊热效率测量的不确定性。为了了解量热仪参数对测得效率的影响，针对每种电弧功率条件进行了两因素，两水平全因数设计。在这项研究中，因素是流速（2 l / min和5 l / min）和板厚（0.25英寸（6.35毫米）和0.375英寸（9.53毫米））。结果表明，同时使用较高的流速和板厚时，热效率测量的不确定性会增加。而且，使用厚板会导致传热方式发生变化，增加冷却速率并降低观察到的热效率。不确定性还受焊接过程中金属传输方式的影响。