Preheating of austenitic stainless steel for cold forming

Research output: ThesisMaster's Thesis

Organisational units

Abstract

To outperform competition in the market of metal anchors it is crucial to keep the product quality as high as possible and the price as low as necessary. Although the process of cold forming is well established, there is still optimization potential. In order to rise the performance and load limit of the anchors, different geometries in combination with high-strength steels are necessary. As a result, the machines, the forming and rolling dies suffer higher wear, which leads to high production costs. To get a rough idea of the flow properties in advance, crush tests on wire-samples had been done. With a better understanding of the flow behavior of different materials and therefore better possibilities of doing an improved computer-aided simulation previously, tests at the - cold former can be defined more preciously and efficient. As expected the flow properties of the tested material 1.4404 improve with increasing temperature of the sample. The ideal preheating temperature for this material seems to be 300° C. No significant change in flow properties were detected between 300° C and 400° C and over 400° C the possibility of forming carbides in the microstructure is too high, which would negatively impact the corrosion resistance of the material. Looking for methods to increase the lifetime of the components in the cold former, preheating of the wire seems to be an appropriate solution. With better flow properties and less strength of the material at higher temperatures the tool wear could be decreased. To verify this assumption, tests have been planned on cold former which is already used for the metal anchor production. In order to heat the wire before the forming process an inductor operated by a generator was mounted in the cold former. Due to the fact, that the power of the used generator was not high enough, 300° C could not be reached. The maximum temperature reached with the testing setup was around 150° C, which had no positive influence on the forming force. Nevertheless, small improvements at the thread rolling process, according to geometry and decrease of forces were determined.

Details

Translated title of the contributionVorwärmen von rostfreiem austenitischem Stahl für die Kaltumformung
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
Supervisors/Advisors
Award date19 Oct 2018
Publication statusPublished - 2018