Results of Auto/Steel Partnership (A/SP) Steel Tube Hydroforming Materials and Lubricants Experimental Projects

Over the past twelve years the Auto/Steel Partnership (A/SP) Tube Hydroforming Materials and Lubricants Team has been conducting projects to aid the implementation of tubular hydroforming in automotive applications. The approach taken has been to initially gain a basic understanding of the hydroforming process and potential issues and to then extend learning to real world applications of increasing complexity.

The experimental project investigations have encompassed various steel grades with a recent focus on advanced high strength steel (AHSS) and tailor welded tubes (TWTs) in free expansion and corner fill processes using several types of lubricants.

Project plans are developed based on identified knowledge gaps, barriers to implementation and technology needs as follows:

• Effects of forming operations prior to hydroforming including tube making, pre-bending and pre-forming.
• Forming limits (e.g. forming limit diagrams (FLDs)) and other failure criterion.
• Experience with AHSS in hydroforming applications is limited.
• Attitude is conservative toward new materials and envelope-pushing applications.
• Need to demonstrate the benefits of tube hydroforming through projects focused on real world applications
• Limited computer modeling knowledge and lack of validated tools for automotive design process.

This paper will review a few of the projects that have been conducted by the A/SP Hydroforming Materials and Lubricants Team as well as present results and major findings of these projects. The entire database of experimental results and learning is available for use by other researchers to support implementation of steel tube hydroform automotive solutions and for validation of computer models through A/SP (www.a-sp.org).