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Products and solutions, 2004-09-22, 02:00 AM

ThyssenKrupp Umformtechnik uses Microzinq D4 galvanizing process

High corrosion protection - low weight

Vehicle weight, corrosion protection and environmental compatibility are central factors in automotive construction. Chassis components in particular have to meet high corrosion protection standards.

In the manufacture of these products, hot-dip galvanizing is an established process offering outstanding corrosion resistance and mechanical strength. However, the zinc coatings have one serious drawback: their thicknesses of 60 to 100 µm increase component weight.

The Microzinq D4 batch galvanizing process offers a strong alternative. Innovative, hexavalent chromium-free and therefore environmentally compatible, it produces coatings in thicknesses of 10 to 20 µm on average, thereby adding considerably less to component weight than hot-dip galvanizing.

How do Microzinq D4-coatings perform in terms of corrosion protection? Recognized auto industry tests show that the degree and durability of corrosion protection achieved with the new process are comparable to the properties of conventional galvanized coatings in thicknesses of 60 - 100 µm. In terms of chip resistance, a key requirement for chassis components, the new coatings achieve even better results in salt spray tests and German auto industry association (VDA) tests. Compared with the conventional zinc-coating process (ISO 1461) Microzinq D4`s higher aluminum concentration makes the active protection mechanisms up to four times more effective under long-term exposure. Corrosion resistance was verified in tests by independent institutes (including salt spray test to DIN 50021, cyclic corrosion test to VDA 621-415, Kersternich test to DIN 50018-KFW0,2).

ThyssenKrupp Umformtechnik believes the potential of the Microzinq D4 process is not restri­cted to chassis components. Structural components consisting of two or more parts joined together by special joining techniques such as seaming and resistance/spot welding can also benefit from the process. The soldering effect of the Microzinq process can increase component stiffness by up to 40%, opening up further potential for weight reduction. As component stiffness is a fundamental design criterion, especially for axle components, it is possible to partially dispense with additional reinforcements or reduce material thickness.

A further interesting effect relates to the heat input in the component needed in the Microzinq D4 process. With selected steel materials, the bake-hardening effect can be used to enhance component strength. Furthermore, compared with conventional processes, Microzinq D4 requires lower process temperatures, and controlled pre-heating reduces the risk of component distortion. Special pretreatment baths together with the high aluminum content in the zinc bath ensure the application of an thin coating. With specific materials, the heat input can increase the service life of the component.

ThyssenKrupp Umformtechnik uses the Microzinq D4 process in the production of chassis components to effectively meet the demands of the auto industry for reduced weight and improved component characteristics.

Contact:

ThyssenKrupp Automotive AG
Thomas Jungbluth
Tel. +49 234 9 19-6013
Fax +49 234 9 19-6015
E-Mail: jungbluth@tka.thyssenkrupp.com

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