CORROSION BEHAVIOR AND TENSILE PROPERTIES OF AUSTEMPERED DUCTILE IRON AFTER LONG TIME IMMERSION IN WATER
长时间水浸泡奥贝球铁的腐蚀行为及拉伸性能

The corrosion behavior and tensile properties of austempered ductile iron(ADI) immersed in water for a long time was investigated from the viewpoints of corrosion and water embrittlement.Matrix adjacent to graphite nodule was eroded away and corrosion pit formed when ADI was immersed in water for a long time.And acicular ferrite in matrix was corroded preferentially.The tensile strength and elongation of ADI tested under the wet condition after immersion in water for 480h,were lower than non-immersed specimen,i.e.the drastic water embrittlement was observed.When specimens were immersed in the tap water for a long time,the tensile strength and elongation were recovered to a certain degree after drying.The tensile properties of specimen dried after immersion were not completely recovered to the level tested in air because of reduction of cross sectional area due to the corrosion pits and surface dissolution.When the specimens were immersed in tap water for a long time,the water embrittlement was more remarkable than the specimen immersed in ion exchange water.This is because of the corrosion of specimen was promoted by tap water.