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灰铸铁是一种导热性能十分优良的金属材料。因此,在经受热循环载荷的工况条件下如钢锭模,玻璃模具等场合至今还大量使用普通灰铸铁材料。灰铸铁在处于低温-高温-低温的热循环过程中,常常会产生横向、纵向裂纹或者在内表面产生龟裂、凹坑而失效。在某种意义上讲,钢锭模、玻璃模具等报废的主要原因是模裂,而模裂主要是由于材料所受的应力超出了固有强度所引起的。模具在受热和冷却时所受的主要应力是组织应力和热应力。此时,内外表面金相组织的奥氏体化与奥氏体冷却时内外表面向珠光体和铁素体转变的时间有较大差异,同时珠光体受热也会向铁素体转化、铁素
Gray cast iron is a very good thermal conductivity of metallic materials. Therefore, under the conditions of thermal cycling load conditions such as ingot mold, glass mold and other occasions so far also extensive use of ordinary gray cast iron material. Gray cast iron in the low temperature - high temperature - low temperature thermal cycling process, often have horizontal and vertical cracks or cracks in the inner surface, pit failure. In a sense, the main reason for discard ingot molds, glass molds and the like is mold cracking, which is mainly caused by the stress beyond the intrinsic strength of the material. The main stresses the molds experience when heated and cooled are the stress of the structure and the thermal stress. At this time, the internal and external surface microstructure austenite and austenitic inner and outer surface cooling time to pearlite and ferrite transformation are quite different, while pearlite heat will be transformed to ferrite, ferrite