Defects and Remedies in Stamping of Advanced High Strength Steels

Abstract

Abstract: In recent years, the use of advanced high strength steels (AHSS) in the automotive industry has increased due to their potential in reducing weight, leading to lower fuel consumption and carbon dioxide emissions. The AHSS structures would be the optimum choice for many applications; however, there are many defects to overcome in their stamping. In this present study, different types of defects and remedies of AHSS stampings are presented. Keywords: Advanced high strength steel, AHSS, Failure analysis, Damage behavior of multiphase steels, Failure prediction. 1. INTRODUCTION Lightweight materials, such as composites, aluminum, and magnesium alloys are commonly used in the automotive and aerospace industries. However, when lower density materials (such as Al and Mg alloys) are used, thicker parts are required to compensate for their lower strength. In addition, there are some difficulties in the cold forming of such low-density alloys. After the oil crisis in the 1970s, the steel industry has started to develop the dual-phase (DP) steels (ferritic-martensitic) in order to decrease fuel consumption and exhaust tail pipe emissions. DP steels are part of broader type of steels which are known as advanced high strength steels. These AHSS offer up to five times the strength relative to the mild steels. Therefore, they can be an attractive alternative to lightweight materials in achieving lightweight structuring. Obviously, AHSS are not considered to be lightweight materials, however; due to their high yield strength, the sheet thicknesses can be significantly reduced and consequently weight reduction can be achieved. Advanced high strength steel tubes are currently used as side impact door beams, seat structures, and instrument panel beams in automobiles [1]. AHSS have been being increasingly used in automobile structural components due to their corrosion resistance, toughness, and high resistance to impact. In specific, Martensitic Steels (MS) are typically used to provide collision protection by minimizing the deformation from sideward impacts [2]. A more extensive use of AHSS in the automotive industry would cause a significant reduction in weight without