磨辊开裂原因分析

磨辊在热处理之后发生开裂，裂纹宏观形貌平直。为寻找开裂原因，对开裂磨辊进行了化学成分和高、低倍组织及断口的宏、微观分析。检验结果，宏观断口上有较多白亮斑，低倍试样上分布大量锯齿状白点裂纹；用SEM观察断口的白亮斑区有不连续二次裂纹，二次裂纹边缘分布多个穿晶准解理平台，平台微观形貌与白点的微观形貌特征相符；金相组织是由粗大马氏体、贝氏体和珠光体与铁素体组成的混合组织，且有不连续分布的穿晶锯齿状裂纹，裂纹周围未脱碳。结果表明，磨辊开裂是由白点引起的，而白点裂纹的形成与磨辊材料的氢含量和热处理组织缺陷等因素有关。

CRACKING ANALYSIS OF GRINDING ROLL

A grinding roll was cracking after heat treatment. The cracks appearance looks straight. The cracked grinding roll was examined through the chemical composition analysis, macro-and micro-fractography as well as microstructure. The results show that the macro-fracture surface has light spots, and metallographic observation at low-magnification revealed a lot of serrated cracks. The flake caused the grinding roll cracking. The micro-fractography showed discontinuous secondary cracks. Around the secondary cracks, there are many transgranular quasi-cleavage facets, which micro-appearance consistents with one of the flake. Microstructure was mixture of crassitude martensite, bainite, pearlite and ferrite. Metallographic surface has serration transgranular cracks discontinuouly distributed. Around the cracks there are no decarbonized. It can be concluded, that the grinding roll cracking was caused by flake. The formation of the flake was related to hydrogen content of the material, heat treatment microstructure defects and other factors.