Cost Effective High Strength Electric Resistance Welded Tubes For Structural Applications 2010-01-1912

The properties of Cold drawn electric resistance welded, as drawn (CEW-AD) tubes and Electric resistance welded (ERW) tubes are vastly different. Deformation resistance of ERW tube is less than half that of CEW-AD tube, hence not preferred for structural applications, common practice being the use of CEW-AD tubes for Chassis cross members in vehicles. A new cost effective high strength ERW tube was developed which has been proved to be superior to the currently used CEW-AD tubes in terms of mechanical properties, formability, consistency and uniformity of the properties over the tube length. The newly developed tube through use of special micro alloy grade in ERW has made it possible to eliminate some of the manufacturing processes like annealing, phosphating, cold drawing etc. which has led to considerable cost saving. Apart from the saving in cost and superior performance, elimination of certain non eco-friendly processes required for conversion to CEW-AD grade has made the manufacturing process leaner and greener. As additional advantage, this development also enables the designer to locate the wiring harness holes away from the weld line which for an ERW tube would be clearly discernible.

The chemistry of this tube has been patented. These tubes are currently specified for chassis cross members of premier small segment mini goods carrier and is being further extended to light commercial vehicles. This has served to commonize the material grade for a series of vehicle platforms and also derive maximum cost saving, given the huge requirement. Apart from this, a clear potential exists for replacement on other structural parts with non-pressurized applications, thereby further expanding the integrated cost saving. The paper presents the work carried out and concept behind the development of high strength ERW tubes , highlighting the tangible and intangible benefits in such development.