Common Defect Analysis for Large Section Special Steel Forging

Abstract:

In order to Figure the common defect in large section special steel forging and find the solution, systematic study was carried out on hundreds of large section special steel forgings in a domestic famous steel mill. The steels included: low-carbon steel Q345D/E, medium-carbon steel 27SiMn, high-carbon steel GCr15SiMn, stainless steel 20Cr13. Both the amount and type of all the defect in the above steel were calculated and analyzed. The results showed that the common defects of the steel were slags, inclusions, loose (cavity) and inner cracks. The evolution of the cavity in the ingot during forging process was simulated by a numerical simulation software Deform-3D. The inner cracks in Q345D/E and 27SiMn initiated after A→F+P transformation The cracks in GCr15SiMn formed after the precipitation of net-like proeutectoid carbides. The cracks in 20Cr13 formed after the precipitation of net-like carbides. The internal cause of the cracks was relevant to composition segregation and internal stress in the forging. The external cause was connected with effect of slow cooling. Based on the above study, a set of new process was proposed and put into industrial application, with the result that the qualified ratio of flaw inspection in the above steel mill was improved from 20% to above 87%.

• Periodical: Materials Science Forum (Volume 898)
• Pages: 1208-1214
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.898.1208
• Online since: June 2017
• Authors: Xin Li Wen*, Jian Peng Gao, Yuan Guo La
• Keywords: Cavity, Common Defect, Heat Treatment, Inclusions, Inner Crack, Large Section Sepcial Steel Forging, Slags

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