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|Title:||Slow cooling of hot rolled bars to eliminate hydrogen induced cracks in Cr-Mo steels|
Nagashanmugam, K B
|Keywords:||Ultrasonic testing;Defects;Microstructure;Hardness;Hydrogen induced cracks;Slow cooling|
|Abstract:||Hydrogen shows a high diffusivity in the solid phase and tends to escape during cooling, which reduces its concentration in steel. Low concentration of hydrogen is advantageous as it prevents hydrogen induced cracks. To ensure maximum removal of diffusible hydrogen, slow cooling of steel bars is investigated at JSW Steel Ltd, Salem Works (JSWSL). The hot rolled bars of Cr-Mo steel blooms such as 42CrMo4 and SCM 440H are slow cooled in a thermally insulated mild steel box. The effect of slow cooling on the microstructure, hardness and ultrasonic testing of bars are studied. The present paper discusses the results of slow cooling experiments conducted with Cr-Mo steel blooms and compares the properties of slow cooled and air-cooled bars. The slow cooled bars exhibited reduced hardness up to 78 BHN and are found to be free from ultrasonic defects when compared with air-cooled bars.|
|ISSN:||0975-1017 (Online); 0971-4588 (Print)|
|Appears in Collections:||IJEMS Vol.22(3) [June 2015]|
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