奥 - 贝球铁焊接HAZ组织性能与断口分析

ANALYSIS OF MECHANICAL PROPERTIES AND FRACTURE MORPHOLOGY ON HAZ OF AUSTEMPERED DUCTILE IRON WELDING

利用Ｇｌｅｅｂｌｅ－１５００焊接热模拟试验机，通过改变峰值温度Ｔｍ、高温停留时间ｔｍ和冷却速度ｔ８／５，研究了奥－贝球铁焊接ＨＡＺ力学性能和断口形貌。当Ｔｍ增加时，强度σｂ下降，断口由准解理断裂形貌过渡到脆断形貌；在ｔｍ增加时，强度σｂ缓降，断口脆断逐渐明显；而当ｔ８／５增加时，强度σｂ增加，在ｔ８／５＝４０ｓ达到最高值，当进一步增加ｔ８／５，强度σｂ略有下降，断口表现为珠光体组织中铁素体与渗碳体分开特征，并证明奥氏体区是ＡＤＩ焊接接头力学性能最薄弱的区域。

オsing the Gleeble1500 welding thermal simulation test machine, the effect of peak temperature (Tm), holding time (tm) at Tm and cooling time (t8/5) from 800℃ to 500℃ on mechanical properties and fracture morphology of HAZ of austempered ductile iron welding has been studied and some experimental results have been obtained. With raising Tm, fracture strength (σb) decreases and fracture morphology develops from quasicleavage to cleavage fracture. With increasing tm, σb decreases and cleavage fracture displays clearly. With further increasing t8/5, σb is greatest in t8/5=40 s and then σb decreases slightly, fracture characteristic is that ferrite and cementite in pearlite are split. Meanwhile, the results prove that mechanical properties of austenite zone of HAZ is weakest in joint of ADI welding.