Development of High Strength Steel Sheets for Wheel Rim Use

Three types of hot-rolled high strength steel sheets having tensile strengths of 600 to 800MPa for wheel rim use were developed. For a fundamental study the effects of chemical compositions on the formability in stretch-flanging and bending on the flash butt welded joints were investigated. In precipitation-hardened steels, the main controlling factors are identified as a newly proposed carbon equivalent value, Mn/Si ratio and S content in steel. P-bearing steels and intercritically heat-treated dual-phase steel hoops are able to be used for rim production. Examples of commercial production of rims are presented.