Forged Rolls for Cold Rolling Mills

In order to produce rolls with high resistance to wear, spalling and improved surface properties, the manufacturing process starts with vacuum degassed bottom poured ingots. The blanks are manufactured with proper forging ratio using minimum capacity of 2000 tonnes hydraulically operated pull down type press.

The gas (Hydrogen, Nitrogen & Oxygen) content of the blanks is kept within the maximum limit of 150 ppm (keeping hydrogen within 2 ppm) and inclusion rating is limited within 2 thin series as per ASTM E45.

The final microstructure contains predominantly fine tempered martensite, and globular carbides. To achieve the same, the blanks undergo a series of stringent heat treatment cycles, closely monitored through programme logic control. This include pulse fired annealing furnace of Sanken Sangyo, Japan. To improve the basic microstructure of the blank, UCON/ polymer quenching is undertaken to control the journal microstructure and hardness. Thereafter the rolls undergo tempering cycle in vertical electric furnace before sending it for induction hardening in low frequency induction furnace from TOSHIBA, Japan, which ensures barrel surface hardness of up to 98 to 100 deg. HSD as per JIS or equivalent. All rolls are further subjected to subzero treatment by liquid nitrogen quenching to attain the most stabilized structure by minimising retained austenite. Necessary steps are taken to minimize the residual stresses and ensure maximum toughness of the roll.

These rolls find application in various cold rolling mills as work rolls, intermediate, skin pass and back up rolls in tandem and reversing mills.  Our present manufacturing range extends from 240 mm to 605 mm in barrel diameter.

NOMINAL CHEMICAL COMPOSITION & MECHANICAL PROPERTIES