含孔洞缺陷焊接接头放电强化及疲劳寿命分析

针对焊接接头中存在的孔洞等形式的缺陷，利用自制的ZL-2型超强脉冲放电装置对含孔洞缺陷的9CrSi合金工具钢焊接接头进行了电磁热强化试验，并在自制的疲劳试验机上对放电前后焊接接头的疲劳寿命进行了对比分析，从理论上计算了含孔洞缺陷焊接接头放电瞬间的综合应力强度因子.结果表明，放电电压对疲劳寿命的影响存在最优值，在5.5 kV脉冲放电电压作用下，放电后的焊接接头平均疲劳寿命比放电前提高了10%以上，理论计算的电热应力强度因子为负值，削弱了裂纹扩展的驱动力，进而延长了试件的疲劳寿命.

Fatigue life and strengthening research of welded joints with hole defects by using electromagnetic heating

Aiming at the hole defects in the welded joints, by the ZL-2 super pulse discharge generator, the welded joints of 9CrSi steel with hole defects were discharged by electromagnetic heating and the fatigue life were tested before and after discharge by using self-designed fatigue testing machine. The discharging instant stress intensity factors were theoretically calculated. The result shows that there is an optimal discharge voltage for the fatigue life. Under the action of 5.5 kv pulse discharge voltage, the average fatigue life of welded joints after discharge are increased by 10%. The electrothermal stress intensity factor is negative that weaken the crack driving force, thereby extending the fatigue life of the welded joints.