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Nalawade R.S.,Kalyani Carpenter Special Steels Pvt. Ltd. | Patil P.P.,Kalyani Carpenter Special Steels Pvt. Ltd. | Balachandran G.,Kalyani Carpenter Special Steels Pvt. Ltd. | Balasubramanian V.,Kalyani Carpenter Special Steels Pvt. Ltd.
Transactions of the Indian Institute of Metals | Year: 2016

The void closure phenomenon of a large size rolled bar made from an as-cast low alloy steel ingot of grade AISI 4130 has been examined. The study involved FEM based simulation of hot rolling of a four metric ton ingot casting to a final product of 320 mm round corner square cross section with a reduction ratio of 4.3. The rolling process was varied at two process conditions. The process variables considered included initial cooling time of the ingot from soaking pit before rolling, rpm, reduction and pass schedule. The defects in the product at the two rolling conditions were experimentally evaluated using ultrasonic technique during hot rolling and compared with void fraction in the simulation. Higher initial time of cooling of the ingot before hot rolling, lower rpm, higher reduction and lesser number of tilts gave products with least core defect which justified simulation results. The study brought out at every stage the load and torque distribution, effective strain, stress triaxiality factor, void volume fraction and void healing hydrostatic integration parameter in the model which had enabled void closure. © 2016 The Indian Institute of Metals - IIM Source


Kuikarni S.,Kalyani Carpenter Special Steels Pvt. Ltd. | Srinivas P.,Kalyani Carpenter Special Steels Pvt. Ltd. | Biswai P.K.,Kalyani Carpenter Special Steels Pvt. Ltd. | Balachandran G.,Kalyani Carpenter Special Steels Pvt. Ltd. | Balasubramanian V.,Kalyani Carpenter Special Steels Pvt. Ltd.
ASM International - 28th Heat Treating Society Conference, HEAT TREATING 2015 | Year: 2015

The 13% Cr 0.2%C steel is extensively used in OCTG application. This steel was examined in the double hardened condition at 1040°C/OQ followed by 980°C/OQ as against conventional hardening treatment at 980°CIOQ. It was observed that the double hardening heat treatment resulted in higher carbon dissolution in the matrix without any residual grain boundary necklace carbides while single hardening at 980°C shows remnant grain boundary carbide. Double hardening heat treatment was found to refine the grain size by recrystallization of the defects introduced in first hardening. During double tempering heat treatment, the carbides in the 980°C treatment were coarse and found to nucleate along grain boundary. The double hardened sample on tempering showed an even distribution of carbide throughout without grain boundary carbide. The double hardened sample show improved strength and toughness compared to the single hardened sample at similar tempering conditions. The microstructural analyses at various stages of processing have been correlated to the mechanical properties obtained. © 2015 ASM International®. Source

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