【摘要】 对GJW50钢结硬质合金进行了20℃~680℃的热循环试验,研究了该合金热疲劳裂纹萌生及扩展机理,重点研究裂纹在其宽度方向上的扩展机理。结果表明:经过一定次数的冷热循环后,与缺口边缘垂直方向萌生多条平行裂纹,其中在缺口尖端处与热循环方向平行的一条微裂纹发展成为主裂纹。裂纹在萌生过程中伴随着严重的氧化腐蚀,二者相互影响,氧化腐蚀促进裂纹的萌生。在主裂纹长大的过程中,与主裂纹平行方向和垂直方向同时萌生多条相互平行的微裂纹;这些微裂纹随着循环次数的增多而长大,最终与主裂纹相连相通,形成主裂纹在宽度方向上的扩展。更多还原

【Abstract】 Thermal cycle test of GJW50 steel bonded carbide at 20～680℃ was performed.Initiation and propagation mechanism of thermal fatigue cracks at notch tip of samples was investigated.The results show that several thermal fatigue cracks are observed at the edge of the sample notch in vertical direction to the edge after several thermal cycles,and only one microcrack among them developes into the main crack.There is serious oxidation and corrosion of the microcracks accompanied with crack initiation and its early growth,conversply,the oxidation and corrosion promote initiation of cracks. There are several parallel cracks near main crack grow continuously during the main crack growing process and finally they connect with the main crack causing the propagation of the main crack at width direction.更多还原