A UNION OF OPPOSITES

Waelzholz’s PT-strip and RAWAEL® materials are both excellent choices for complex components with high tensile strength – since they are factory-produced with high strength and good formability, parts made from these grades do not need to be piece-hardened. This reduces the number of processing steps. In addition, eliminating piece hardening makes it possible to achieve extremely tight tolerances in the final product.

Complex formed components that need to have high tensile strength are often manufactured from soft materials and are subsequently piece-hardened. But this method has some drawbacks. On the one hand, piece hardening after forming is a cost-intensive additional processing step. On the other hand, heat treatment after forming always has a considerable impact on the form, positional, and dimensional tolerances. Waelzholz’s bainitically hardened and tempered PT-strip and micro-alloyed fine-grained steel RAWAEL® are two intelligent alternative materials. Both were developed to meet high load requirements – PT-strip and RAWAEL® offer tensile strengths beyond the 1,000 MPa (145 ksi) mark. Despite their strength, both materials are suitable for complex forming operations such as hole outlines with a collar or dome-shaped drawing, notches, and bead embossing. Thanks to their homogeneous microstructure, the differences between the cold rolled steel strip’s longitudinal and transverse directions are minimal. Figure 1 shows the various forming options possible with a sample application.

Two high-strength materials – a wide range of applications

Both high-strength materials are very similar when it comes to their yield strength, tensile strength, and elongation (Figure 2). Nevertheless, the materials differ significantly in their finer details, which means they are each recommended for specific fields of application.

PT-strip is manufactured from carbon steel with a carbon content between 0.4% and 0.7%. This ensures that PT-strip exhibits excellent spring properties in a hardened and tempered state. As such, the material is particularly suitable for punched and bent components and spring applications with dynamic loads. PT-strip is used, for example, to manufacture connecting, fastening, and spring clips for mounting applications.

RAWAEL® has a very fine monophasic microstructure. In contrast to PT-strip, the high tensile strengths of RAWAEL® are achieved via special cold rolling processes of the fine microstructure and the resulting precipitates. Due to its minimal carbon content of < 0.1%, the material exhibits outstanding joining properties and can, therefore, be welded. In relation to the material’s tensile strength, RAWAEL® offers a considerable weight advantage. The material is used, for example, for seat tracks in motor vehicles or for gearbox plates.

In contrast to soft materials that are piece-hardened after forming, both high-strength materials offer exceptional form, positional, and dimensional tolerances. This gives our customers a significant degree of design freedom. PT-strip and RAWAEL® are manufactured with extremely homogeneous processing and forming properties and maximum consistency in terms of their mechanical and technological characteristics. This ensures that our customers’ components exhibit a high degree of reproducibility, which creates real market advantages.