提高焊接接头疲劳强度的超声波冲击法

Ultrasonic Peening Method to Improve Fatigue Strength of Welded Joint

通常采用打磨焊趾的方法来改善焊接接头的疲劳强度，而使 用超声波冲击焊趾来提 高焊接接头及结构的疲劳强度，是一种国际上刚刚出现的新方法。本文研制成 功了一种基于压电陶瓷 换能器的新型超声冲击试验装置。实际使用过程表明：其执行机构体积小、重量轻、噪音极小、耗能 低、使用灵活方便，易于实施。利用该设备，采用 Ｑ２３５ 钢进行了冲击 处理效果的验证性对比疲 劳试验。试 验结果表明：超声冲击方法对焊接接头疲劳强度的改善效果十分明显，能够提高疲劳寿命２０ ～３０ 倍以上，极具实用价值。同时发现，超声冲击处理能够有效地消除焊趾处 浅层裂纹、夹渣等焊接缺陷，该作用 也是其提高焊接接头疲劳强度的原因之一。

As known to all,to improve the fatigue strength of welded joints,it is necessary to polish the weld toe.Recently it has been found that the fatigue life of welded joint can be increased dramatically by ultrasonic peening the weld toe.In this paper,a ultrasonic peening device based on piezoelectric ceramic transducer is firstly developed successfully.This equipment is convenient because of its small size、light weight、low power consumption as well as other merits.In order to study the effectiveness of peening treatment with the equipment,the fatigue tests has been carried out in Q235 steel.The results show that the fatigue life of the peened joint is 20～30 times as long as the as-welded joints .Therefore,the improvement of the fatigue strength of welded joints by ultrasonic peening is remarkable.It is seen that the weld defects such as shallow cracks and slags at the welded toes can be removed effectively during the ultrasonic peening process.That is a reason for improving the fatigue strength of welded joints with this technique.