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As more and more high strength and advanced high strength steels are being utilized into automotive body panels, structural beams and rails to reduce weight to meet the Café (Corporate Average Fuel Economy) requirements, wear of stamping dies is becoming a major issue. Many types of coatings/surface treatments such as: thermal spray, ion nitriding, chrome plating, PVD, CVD, and TD coatings are being used in stamping plants. Identifying a cost-effective coating and the die material based on the types of the advanced high strength steels is difficult since there is little data available. None the less on the real die. This paper will discuss the evaluation of the coatings and die materials on a B-pillar draw die. The coatings and die materials were chosen based on laboratory design of experiment tests and the typical die materials used in stamping plants.

As high strength steels are introduced into automotive stamping applications to satisfy CAFE (Corporate Average Fuel Economy) and fuel economy requirements, wear of stamping dies is becoming a major issue. Many types of coatings/surface treatments such as: thermal spray, ion nitriding, chrome plating, PVD, CVD, and TD coatings are being used. Choosing the best coating is difficult since there is little data available to compare all types of coatings under the same operating conditions. A laboratory pin on flat test procedure was developed and utilized to compare the wear resistance of various coatings. SEM pictures of wear scars of coated pins indicated that coatings can effectively protect the substrate material from wear. Without coating the substrate material wears away rapidly. The test results showed that hard chrome performed well when run against various sheet materials, but its wear resistance was significantly lower than high temperature coatings.

Tailor welded steel blanks have long been applied in stamping of automotive parts such as door inner, b-pillar, rail, sill inner and liftgate inner, etc. However, there are few known tailor welded aluminum blanks in production. Traditional laser welding equipment simply does not have the capability to weld aluminum since aluminum has much higher reflectivity than steel. Welding quality is another issue since aluminum is highly susceptible to pin holes and undercut which leads to deterioration in formability. In addition, high amount of springback for aluminum panels can result in dimension control problem during assembly. A tailor-welded aluminum blank can help reducing dimension variability by reducing the need for assembly. In this paper, application of friction stir and plasma arc welded blanks on a liftgate inner will be discussed.

In order to increase the strength and formability of batch annealed sheet steels, design of experiment method was used to set up an experimental matrix with five factors, including C, Mn, P in steels, coiling, and batch annealing temperatures, at two levels. Effects of these factors were analyzed using analysis of variance and linear regression methods for cold spot and hot spot, respectively. Linear regression results showed that higher alloying element contents and coiling temperature will increase strength and deteriorate elongation, which is opposite to the effect of annealing temperature. Analysis of variance showed similar results to those of linear regression, except the effect of C on elongation and effect of coiling temperature on tensile strength and elongation are negligible for cold spot. For hot spot, effect of coiling temperature on tensile strength is small.