The Reasons Analysis and Controlling Measures on Ultrasonic Tested Defects of 4Cr13 Die Steel
In order to solve the defect issue of 4Cr13 steel produced by mold casting process,the cause analysis was conducted by scanning electron microscope and energy dispersive spectrometer,and improvement measures combining production process were proposed in this paper.The results showed that there are two types of defects,one is point defects at the head and tail of the steel plate,and the other is linear defects in the central area.Point defects are mostly calcium aluminate inclusions dominated by CaO and A12O3,while linear defects in the central area are caused by internal shrinkage cavity or porosity in the ingot steel.Improvement measures were proposed to optimize the RH treatment process,optimize the use of ingot type,and extend the sedation time in response to the causes of defects.The defect rate of 4Crl3 thick plates was significantly improved,decreasing from an average of 33.5％to 4.5％.
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