Research on the friction properties of DP600 stainless steel as a function of bending angle and pin diameter

The rapid evolution of materials and manufacturing processes, driven by global competition and new safety and environmental regulations has had an impact on automotive structures (Body In White) manufacturing. The need for lighter vehicles, with more equipment, safer and eco-friendly at the same time, covers the entire life cycle of the car. Car and steelmakers agree that weight reduction is possible, and the solution goes through the use of new Advanced High-Strength Steels. Thinner and stronger materials lead to higher demands on stamping, the most used manufacturing in BIW parts.

The use of Advanced High-Strength Steels raises new challenges, especially concerning the lubrication between the die and the sheet. To study the lubrication conditions of the stamping process a sheet metal forming simulator has been developed. The simulator consists of two cylinders that pull the strip of steel and a pin in between. The angle between cylinders can be adjusted from 0 to 90 degrees which allows analyzing the effect of the stamping angle. The pull force and velocity can be set and measured; and the peripheric pin velocity, the strain, and the strain velocity can be measured as well.

In this work, the tribological properties of Dual-Phase 600 stainless steel using different lubricants have been analyzed. To this end, a Factorial Experiments Design with twelve parameters that compare the behavior of different lubricants has been run. The results showed that the friction coefficient increases by increasing the bending angle and pin diameter.