Search Results

This paper deals with the use of small amounts of certain alloying additions, primarily columbium and vanadium, to enhance the mechanical properties of cold finished and hot roiled bar products. Hot rolled products with guaranteed tensile properties are readily produced by this approach; moreover, the application of microalloyed bars has successfully eliminated the need for heat treatment of various hot forged parts such as universal joint couplings, stabilizer bars, as well as connecting rods and caps. A typical example of this approach will be presented. High-strength, cold finished bars are readily produced by starting with microalloyed hot rolled bars thus significantly expanding the range of properties achievable using a variety of base grades. Mechanical property and machinability data will be presented descriptive of selected commercially available products.

Microalloying is the technique of adding very small amounts of certain elements to steel in order to markedly improve the mechanical properties, most notably the strength and hardness. In 1977, the VanCraft series of high strength microalloyed cold finished bars was introduced. In 1978, this technique has been extended to include hot rolled bars for hot forging applications. Hot forging of steel bars is the technique employed to produce many critical automotive components such as connecting rods, stabilizer bars, and many others. Typically, these parts require subsequent heat treatment to obtain the necessary properties. By microalloying with Cb or V, this heat treatment can often be eliminated since the desired properties are met in the as-forged part. This provides a significant cost savings and, of course, results in a reduction in energy consumption.

High strength low alloy steels with minimum yield strength values in the 50-80 Ksi range are experiencing increased usage in automotive applications for reasons of improved safety and weight reduction. These steels are usually supplied in the hot rolled condition although markets are developing for thinner, cold rolled steels. The increased strength in these materials is usually obtained by grain refinement and precipitation by means of micro-alloying with Cb, V or Ti and by controlled mill processing. The most desirable combination of properties is the development of high strength in the formed part and optimum formability compatible with this capacity for strengthening in the as-shipped steel. This paper deals with the developments at Jones and Laughlin leading to a product, VAN-QN, which has a superior combination of formability and strength in the formed part. Previous descriptions of this type of product have been made by Japanese researchers and M. Rashid of GMC.