The gouging torch process using air carbon arc cutting (CAC) device is a standard maintenance procedure carrying out in high-tonne equipment used in the minery industry. The application of this process could locally affect the mechanical properties and the microstructure in the thermally affect zone (HAZ). The changes involve variation in the local carbon concentration and a tempering effect. In commonly used steels in the manufacture of buckets (SAE 5130) and shovel handles (ASTM 514 grade S), the processes influence negatively the work lifetime and the future maintenance works on the device. Hardness, metallographic analysis trhough optical (OM) and scanning electron microscopy (SEM) were used to evaluate the affected zone. An increasing carbon content up to 2 wt% C was observed in the affected area of the sample, on the slag adhered to it. Presumably, the rest of carbon is lost by evaporation during the process. The hardness measured on the surface of the cut zone shows an increased value for ASTM A 514 grade S, which does not present a notable change for SAE 5130. However, both steels showed a tempering effect. Micro-cracks of 20 to 40 μm appear, and in a few opportunities, a larger crack was found, reaching a total length of 1480 μm.

中文翻译：

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焊炬工艺对铲斗，铲柄和其他高吨采矿设备所用钢材的影响

使用空气碳弧切割（CAC）设备的气刨火炬过程是在采矿行业中使用的高吨设备中执行的标准维护程序。此过程的应用可能会局部影响热影响区（HAZ）中的机械性能和微观结构。这些变化涉及局部碳浓度的变化和回火效果。在制造铲斗（SAE 5130）和铲柄（ASTM 514 S级）的常用钢中，这些工艺会对设备的使用寿命和未来的维护工作产生负面影响。硬度，金相分析通过光学（OM）和扫描电子显微镜（SEM）来评估受影响的区域。在附着于其上的炉渣上的样品的受影响区域中，观察到碳含量增加至2wt％。据推测，其余的碳会在此过程中因蒸发而损失掉。在切割区表面测得的硬度显示出ASTM A 514等级S的增加值，而SAE 5130没有明显变化。但是，两种钢都表现出回火效果。出现了20至40μm的微裂纹，并且在一些机会中，发现了较大的裂纹，总长度达到1480μm。