10、20号优质碳素钢小径管在火电厂中广泛用于500℃以下的锅炉部件,如省煤器、低温过热器及管道部件的疏排水管、热工仪表管、取样管等。这两种优质碳素钢的含碳量较低,为0.08～0.25%,是属于裂纹敏感性低、可焊性良好的钢材,但在火电施工中常发生过热、过烧及热裂纹等缺陷。例如,1975年陕西某火电厂施工中,10多名焊工试焊φ32×3.5 10,20 high-quality carbon steel pipe is widely used in thermal power plant below 500 ℃ boiler parts, such as economizer, low temperature superheater and pipe parts of the drainage pipes, thermal instrumentation tubes, sampling tubes. These two high quality carbon steels have a low carbon content of 0.08-0.25%. They belong to the category of steel with low crack sensitivity and good solderability. However, defects such as overheating, over-burning and hot cracking often occur during thermal power construction. For example, in 1975, a thermal power plant construction in Shaanxi, more than 10 welders try welding φ32 × 3.5