Quality Aspects of Special Forgings of Low Alloy Steels

Within the span of last twenty years, the quality requi-rements of steel forgings has changed drastically. In early Seventies, 80-85% steel forgings belonged to mainly plain carbon steel grades and only about 10-15% forgings are of low alloy steel grades containing Ni, Cr, Mb and V. In the past, the customer asked for chemical composition, hardness, tensile and impact properties only. The ultra-sonic test was not stipulated for the general engineering purpose forgings such as sugar mill shafts, roller etc. At present, 70% of steel forgings belong to low alloy steel grades like 40Ni2Cr1Mo28, 40NiCr1Mo15, En 24, 40 x HM, 38 x 2H2MA, En 30B etc. The quality requirements of these forgings specify rigid ultrasonic quality acceptance norm, Dye penetrant test, less gaseous content, low inclusion count and high impact property. The ultrasonic acceptance norm of critical forgings is 2-4 mm E.F.S (Max. allowable defect size) in D.G.S Scale.
Growing demand for quality forgings has warranted Foundry Forge Plant, HEC to update technology of steel melting, forging, heat- treatment etc and constantly strive for quality improvement through QC, QAP and R&D efforts. At present HEC is able to manufacture critical forgings for mining, shipping, cleience, railway, power, steel plants etc.