Anatomy‐Based Damage Characteristics and Fracture Mechanism of Blast Furnace Ductile Iron Cooling Stave

Ductile iron cooling staves are critical cooling equipment essential for ensuring the safety of the blast furnace. However, Ductile iron cooling staves are prone to fracture under thermal shock, compromising operational safety. Samples were taken from a blast furnace's spherical graphite cast iron cooling stave to investigate damage mechanisms during service. The results indicate that after high‐temperature service, a network of intersecting cracks developed on the surface of the ductile iron cooling stave. The maximum thinning of the stave wall reached 140 mm, accounting for 58% of the original thickness. Results from metallographic microscopy and micro‐CT analysis revealed significant differences in the graphite morphology across different regions of the cooling stave. The tensile strength of the cast iron stave decreased by 14.8%–31.4% after service. Through analysis of the temperature field of the cast iron cooling stave, it is believed that the location of cracks is related to the thermal stress experienced by the cast iron cooling stave. Crack initiation is primarily induced by regions of high stress concentration around nonspheroidal graphite, as well as debonding between spheroidal graphite and the metal matrix. Crack propagation occurs primarily through the graphite phases and extends intergranularly within the metal matrix.