CAJ | 학술논문

利用自行研制的 ZL?2型超强脉冲电流发生装置对带有单边裂纹的 Al-Mg 合金试件进行电磁热止裂实验,并对放电前后裂纹尖端的微观组织进行对比分析;采用热?电?结构耦合的数值分析方法求得放电后试件的电流密度场、温度场及热应力场;从理论上计算放电后的电热应力强度因子.结果表明:放电电压对止裂效果存在最优值;在适当的强脉冲电流作用下,裂纹尖端在小范围内被瞬间强化加热,随后在极大的热压应力作用下快速冷却,组织发生明显变化,晶粒得到细化,并围绕裂纹尖端形成等值压缩热应力,对裂纹尖端有“夹紧”作用,进而阻止裂纹扩展.
이용자행연제적 ZL?2형초강맥충전류발생장치대대유단변렬문적 Al-Mg 합금시건진행전자열지렬실험,병대방전전후렬문첨단적미관조직진행대비분석;채용열?전?결구우합적수치분석방법구득방전후시건적전류밀도장、온도장급열응력장;종이론상계산방전후적전열응력강도인자.결과표명:방전전압대지렬효과존재최우치;재괄당적강맥충전류작용하,렬문첨단재소범위내피순간강화가열,수후재겁대적열압응력작용하쾌속냉각,조직발생명현변화,정립득도세화,병위요렬문첨단형성등치압축열응력,대렬문첨단유“협긴”작용,진이조지렬문확전.
Al-Mg alloys specimens with unilateral crack were used to perform electromagnetic heating crack arrest experiment using a self-made ZL?2 super pulse current generation equipment, and the microstructures around the crack tip were analyzed before and after discharge. The current density field, temperature field and thermal stress field were obtained at the moment of the pulse current discharge by the thermal?electrical?structure coupling numerical analysis method. The electrothermal stress intensity factors were theoretically calculated. The results show that there exists an optimal discharge voltage value for the effect of the crack arrest. Under the action of appropriate super pulse current, the crack tip around small-scale is instantly strengthen-heated, followed by rapid cooling under a great thermal compressive stress. The microstructure has an obvious change, and the grains are refined. And the equivalent heat compression stress generates around the crack tip, which has“clamping”role to the crack tip, and then prevents the crack expansion.