Production of Skin Panels and Other Products for the Indian Automotive Industry - Tata Steel Experience

Avtar Singh, T.Venugopalan, Anand Sen and H.M.Nerurkar
Tata Steel Limited

Since the start-up of cold rolling mill of Tata Steel in April 2000, the principal focus has been on the production of steel grades that would be acceptable for manufacturing automotive components. The effort started with producing Al-killed drawing quality and extra deep drawing quality steels. These are basically low carbon steels, suitable for batch annealing route. With appreciable deep drawing property, extra deep drawing quality steels are used for manufacturing a number of internal components by various car manufacturers such as Tata Motors, Hyundai, Toyota, etc. Tata Steel started manufacturing cold rolled and annealed interstitial free steel in the year 2000 itself, and now batch annealed IF steel is being supplied to many auto customers such as Tata Motors, Ford, Hyundai, etc. This was by far considered the best grade for automotive application, due to its excellent drawability. With the changing trend of automotive industry wherein it was focused on the dual objectives of decreased weight and increased fuel economy, as well as improved dent resistance, Tata Steel started producing high strength IF steel in 2001, with 350 MPa minimum UTS, which is being supplied to Hyundai Motors on regular basis. Gradually, from 2002 onwards, Tata Steel concentrated in developing other high strength automotive steel grades, such as high strength IF steels of 400 and 450 MPa. IFHS-400 is now under regular production and is being used for making the new small truck of Tata Motors, while IFHS-440 is still in trial stage.

Apart from IFHS, rephosphorised Al-killed high strength steels of 350 and 400 MPa UTS have been developed quite satisfactorily, as another family of formable high strength steels, which are now ready for supply to auto makers. This grade is ideally suited for batch annealing route. Bake hardening grades, which are known to offer improved dent resistance after paint baking treatment have also been developed and their suitability has been established for the production of skin panels such as ‘door outer’. Tata Steel manufactures BH-180 commercially and BH-220 grade is under development. Among the other automotive grades, high strength microalloyed steel is being manufactured for Honda, mainly for structural applications. C-Mn high strength steel is another material, which is now under trial. The family of coated automotive steels includes galvanized IF steel (Extragal), which is being exported for European carmakers. The other important materials are galvannealed IF and IFHS-350 grades, which are being supplied to Hyundai, Tata Motors, Proton. One side special chromated GA material has found significant acceptance in 2 wheeler fuel tank applications. Efforts are on to develop galvannealed steel with special coating for 4 wheeler fuel tanks. High strength microalloyed GA grades upto 440 Mpa TS are being supplied for various structural members of auto parts. Many hot rolled grades are also supplied to the automotive customers, mainly for making structural components like long member and cross member. These grades are mainly microalloyed, such as E-34, E-38 and BSK-46. Low carbon drawing quality hot rolled steel is also being supplied to Toyota, after pickling and skin passing for HR draw quality applications. A newly developed ferrite-bainite grade, with about 600 MPa UTS has been developed for the automotive wheel rim application. The current challenge is to improve the strike rate in the production of automotive skin panel quality material. While detailed activities have been undertaken to make it a success, it is being commercially supplied to Toyota, M & M and Tata Motors. Further fine-tuning is on to achieve stringent surface aspect norms. The grades that are under consideration for skin panel application are EDD, IF and IFHS-350 with the main target customers being Maruti, Tata Motors, Hyundai, Toyota, Ford etc. Proton is one of the prospective overseas customers who have expressed interest in procuring IF and IFHS skin panels from Tata Steel. New product development and the product characterisation have helped Tata Steel in establishing themselves as the leading steel supplier to the Indian Automotive Industry.

To meet the stringent draw and quality requirements, Tata Steel had to develop the capability in process and product development, inspection and testing methods, product services and R&D. New concepts / initiatives such as CVM (Customer Value Management), CST (Customer Service Team), EVI (Early Vendor Involvement) and Providing ‘Steel Solution’ have enabled Tata Steel to improve the market share in the automotive segment considerably. Our journey in the ‘Development of Steel for Automotives’ is still ON and with the continued efforts, we hope to develop the steels that will be required by the Indian and overseas automobile manufactureres in the decades to come.

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