我段配属的前进型蒸汽机车,在运行20～30万公里后,在烟箱胴过热箱检查方孔的右下角处易发生裂纹(参阅图1)。从统计情况看,在该处出现裂纹的机车占67％,而未出现裂纹的大都是近年新出厂的机车,估计继续运行后也会出现裂纹。其他车型的机车(如人民型、建设型等),却没有一台出现类似的裂纹。这种烟箱胴开裂的现行修理方法,是焊 I paragraph associated with the forward steam locomotive running 20 to 300000 km, check the smoke box overheated box cracks in the lower right corner of the cracks prone to occur (see Figure 1). According to the statistics, 67% of the locomotives with cracks occurred there. Most of the locomotives that did not show any cracks were newly-built locomotives in recent years. It is estimated that cracks will occur after the locomotives continue to operate. Other models of locomotives (such as people type, construction type, etc.), but not a similar crack. The current method of repairing the cracked box is welding