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焊接结构中，焊接接头的疲劳强度远远低于母材的疲劳强度。大量的实验表明，疲劳裂纹主要起源于接头焊趾处，因此处理焊接接头焊趾将会提高接头的疲劳强度。文中利用自行研制的超声波冲击实验装置，对提高低碳钢焊接接头疲劳强度进行了研究。进行了Ｑ２３５Ｂ钢平板对接和十字接头（熔透）两种接头形式的焊态与冲击处理态的对比疲劳试验，分别获得了两种接头形式冲击处理前后的Ｓ—Ｎ 曲线及疲劳极限（２×１０６）。结果表明，超声冲击处理后，对接接头疲劳极限提高了５８％ ，十字接头提高了６４％ 。
Welded structure, the fatigue strength of welded joints is much lower than the fatigue strength of the base metal. A large number of experiments show that the fatigue crack mainly originated from the weld toe. Therefore, the weld toe processing will improve the fatigue strength of the joint. In this paper, self-developed ultrasonic impact experimental device, to improve the fatigue strength of low carbon steel welded joints were studied. The comparative fatigue test of Q235B steel plate butt joint and cruciform joint (penetration) in the form of welding and impact treatment was carried out. The S-N curve and fatigue limit (2 × 106). The results show that the fatigue limit of the butt joint is increased by 58% and the cross joint is increased by 64% after ultrasonic impact treatment.