Tribology in Forming Advanced High Strength Steels (AHSS)

To improve crash worthiness and fuel economy, the automotive industry is using increasingly Advanced High Strength Steels (AHSS). Forming AHSS often causes lubricant film break down and galling that increases scrap rates and tool maintenance cost. This book introduces a model developed to predict the severity of galling for given lubricants, die materials and coatings in forming galvanized AHSS. Finite Element Analysis (FEA) and various experiments were conducted to develop a galling prediction model. The prediction model considered the empirical relationships between galling and important tribological parameters (e.g. interface pressure, sliding length, surface roughness, lubricant viscosity, hardness of zinc-coatings and tool coatings) in forming galvanized AHSS. This model was applied to estimate the total number of parts that can be formed before severe galling occurs. Therefore, it can offer a cost effective way for automotive stamping industry to select practical and best combinations of lubricant, tool material and tool coating for reducing galling in forming galvanized AHSS.