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依据GB6398-86，采用紧凑拉伸试样（CT），对WEL-TEN780A钢及其用L-80SN焊条手工电弧焊焊接接头的焊缝和热影响区的疲劳裂纹扩展速率进行了研究．结果表明：在相同的疲劳循环载荷作用下，热影响区疲劳裂纹扩展速率高于母材和焊缝，焊缝金属具有最低裂纹扩展速率．焊缝金属中的针状铁索体细小且被大角度晶界所分割，疲劳裂纹扩展时要消耗更大的能量，从而降低裂纹扩展速率，成为止裂型焊缝．
According to GB6398-86, the fatigue crack growth rate of weld and HAZ of WEL-TEN780A steel and its L-80SN welding electrode with hand-held arc welding was studied by compact tensile specimen (CT). The results show that the fatigue crack growth rate in heat-affected zone is higher than that of base metal and weld under the same fatigue cycle load, and the weld metal has the lowest crack propagation rate. The acicular ferrules in the weld metal are small and segmented by the large angle grain boundaries, which consume more energy when the fatigue crack propagates, so as to reduce the rate of crack growth and become a stop-type weld.