@inproceedings{WerschlerGuempelWerner, author = {Werschler, Marco and G{\"u}mpel, Paul and Werner, Konstantin}, title = {Strain-induced martensite evolution in a rolling contact of SS AISI 304}, series = {ESSC \& DUPLEX 2017 : 9th European Stainless Steel Conference - Science \& Market \& 5th European Duplex Stainless Steel Conference \& Exhibition : Bergamo, Italy, 25-27 May 2017}, isbn = {978-88-98990-12-2}, pages = {10}, abstract = {The evolution of strain induced martensite in austenitic stainless steel AISI 304 was investigated in a rolling contact on a two-discs-tribometer. The effects of surface roughness, slip and normal force as well as the number of load cycles were examined. In comparison to the investigations of martensitic phase transformation during cold rolling, the applied stresses are considerably lower. The formation of strain induced martensite was detected in-situ by means of a FERITSCOPE MP30 and ex-situ by optical microscopy after etching with Kane etchant. Both number of load cycles and magnitude of normal force appeared to be the main influencing factors regarding strain induced martensitic evolution in low stress rolling contacts.}, language = {en} } @inproceedings{HoertnaglHamentgenHoferetal., author = {H{\"o}rtnagl, Arnulf and Hamentgen, Michael and Hofer, Beat and G{\"u}mpel, Paul}, title = {Influence of rapid cooling rates for hot isostatic pressing on mechanical and corrosion properties of UNS S32205}, series = {12th International Conference on Hot Isostatic Pressing (HIP17), 5-8 December 2017, Sydney, Australia}, pages = {40}, abstract = {Paper and talk}, language = {en} } @inproceedings{HoertnaglGuempel, author = {H{\"o}rtnagl, Arnulf and G{\"u}mpel, Paul}, title = {Electrochemical characterization of metastable austenitic stainless steels to illustrate the influence of grinding parameters on the corrosion resistance}, series = {CORROSION 2017, NACE International, 26-30 March 2017, New Orleans, Louisiana, USA}, isbn = {978-1-5108-4034-8}, pages = {2635 -- 2646}, abstract = {The electrochemical behavior for different surface conditions and different degrees of deformation of metastable austenitic stainless steel AISI 304 UNS S30400 were studied using critical pitting potential and electrochemical noise measurements. The influence on corrosion resistance by using different abrasives (silicon carbide and corundum) for surface finish by grinding is illustrated. For the characterization of local defects and surface topography, scanning electron microscopy (SEM) and tactile measurements were used. An inverse correlation between occurrence of local defects on the surface and critical pitting potential was found by using image processing. Therefore, gray scale values of different surfaces were compared. The influence of mass content of α'-martensite on the corrosion resistance is shown by comparing different qualities of surface finish. For smooth machined surfaces it can be shown that an increasing numbers of strain induced martensite is decreasing the corrosion resistance lightly. For low abrasive machining an inverse correlation between the critical pitting potential and surface roughness is given. However, for higher abrasive machining parameters, this correlation could not be found.}, language = {en} } @inproceedings{HoertnaglWernerWerschleretal., author = {H{\"o}rtnagl, Arnulf and Werner, Konstantin and Werschler, Marco and G{\"u}mpel, Paul}, title = {Erkennen von martensitischem Gef{\"u}ge in metastabilen austenitischen rostfreien St{\"a}hlen}, series = {Fortschritte in der Metallographie : Vortragstexte der 51. Metallographie-Tagung, 13. - 15. September 2017 in Aalen}, publisher = {Inventum GmbH}, address = {Sankt Augustin}, isbn = {978-3-88355-415-0}, pages = {119 -- 124}, abstract = {Durch Beanspruchungen bei der Fertigung oder in der Anwendung k{\"o}nnen metastabile austenitische St{\"a}hle eine Phasenumwandlung von ?- Austenit zu ?'-Martensit durchlaufen. Verbunden damit sind Eigenschafts{\"a}nderungen, welche sich signifikant auf das Werkstoffverhalten unter mechanischer, tribologischer oder korrosiver Belastung auswirken k{\"o}nnen. Um m{\"o}glichen negativen Auswirkungen wie ungewollte Magnetisierbarkeit oder Beeinflussung von Fertigungsparameter sowie Korrosionseigenschaften zu unterbinden muss die martensitische Phase zun{\"a}chst erfasst und quantifiziert werden. F{\"u}r diese Aufgabe stehen neben den bekannten und kostenintensiven Verfahren wie EBSD und XRD f{\"u}r die praxisnahe Anwendung das magneto-induktive Messverfahren und verschiedene {\"A}tzmethoden zur Verf{\"u}gung. Anhand von Applikationen aus Anwendung, Fertigung und Forschung werden die Wirkweisen, Vorteile und Grenzen verschiedener {\"A}tzverfahren und dem magneto-induktiv messenden FERITSCOPE® MP30 aufgezeigt. Ebenso werden erg{\"a}nzende Methoden bzw. Techniken zur Validation der Verfahren diskutiert und erl{\"a}utert.}, language = {de} } @inproceedings{StrittmatterGuempelLattner, author = {Strittmatter, Joachim and G{\"u}mpel, Paul and Lattner, Oskar}, title = {Potential capabilities of shape memory driven automotive devices}, series = {CONAT 2016 International Congress of Automotive and Transport Engineering, 26.-29. October, Brasov, Rumania}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-45446-7}, doi = {10.1007/978-3-319-45447-4_59}, pages = {536 -- 546}, abstract = {In the automotive industry a strong effort has been undertaken to reduce the weight of modern vehicles. In order to reduce the energy consumption and to improve the environmental sustainability, the importance of weight reduction activities is even growing faster. As lightweight designing is becoming more and more expensive and show less potential savings, new approaches are needed. One promising technology could be the use of shape memory elements. In the last years a lot of potential application possibilities were presented, demonstrating the benefit of these functional elements in automotive design solutions: they often reduce complexity, weight and design space of an actuation device and enable new functions. In addition they work silently and are therefore ideally suitable for comfort applications in the passenger cabin. Because of the current trend to electric vehicle the hitherto existing drawback of a high electrical energy consumption of shape memory actuators in some design proposals is not given any more.}, language = {en} } @misc{Guempel, author = {G{\"u}mpel, Paul}, title = {Werkstoffkunde der rostfreien St{\"a}hle, Aufbau und Eigenschaften}, series = {TAE-Seminar "Rostfreie St{\"a}hle - Konstruktions- und Verarbeitungshinweise", 13.09.2017, HTWG Konstanz}, language = {de} } @misc{KarlGuempel, author = {Karl, Andreas and G{\"u}mpel, Paul}, title = {Oberfl{\"a}chenh{\"a}rtung von nichtrostenden St{\"a}hlen}, series = {TAE-Seminar "Rostfreie St{\"a}hle - Konstruktions- und Verarbeitungshinweise", 13.09.2017, HTWG Konstanz}, language = {de} } @inproceedings{SorgHoertnaglGuempeletal., author = {Sorg, Matthias and H{\"o}rtnagl, Arnulf and G{\"u}mpel, Paul and Dornbierer, Urs}, title = {Corrosion effects on high strength duplex stainless steel nets for offshore fish farming}, series = {EUROCORR 2017 \& 20th International Corrossion Congress, 2.-7. September 2017, Prague, Czech Republic}, pages = {6}, abstract = {As a result of increasing needs and shrinking resources, aquaculture is gaining progressively significance in the recent years. Ecological issues such as negative effects on the ecological system due to the high fish density in the farms, the use of copper as antifouling strategy etc. are very present, particularly regarding the increasing number of fish going to be produced in farms in the future. Current trends focus on larger farms operated offshore. To make these farms working safe and economical, reliability has to be improved and maintenance costs need to be reduced. Also, alternatives with higher mechanical strength compared to current textile net materials as well as common metal wires might be necessary. In the last years, a new net system made of high strength duplex stainless steel wires with environmentally friendly antifouling properties suitable for offshore applications was developed. The first nets are operating for one year now as predator protection (i.e. seals) for fish farms and show a good performance in cleaning capability and predator protection. But in the real usage, some corrosion effects in the contact points of the net made of duplex stainless steel 1.4362 occur which were not observed in preliminary tests in laboratory and at different test sites around the world. These corrosion effects endanger the sustainable success of the net system. In this work, the observed corrosion effects are investigated. A laboratory test, which simulates the movement in the contact points of the net, was developed. Two pieces of wire are bent in the middle and get stucked into each other. One wire is fixed at both ends and the second wire is fixed on one end. On the other end, a circular movement with 1-2 rps and a 1 cm displacement is applied. The movement generates friction between the wires and the passive layer will be locally damaged. When the movement stops, a repassivation starts. The passivity breakdown and the repassivation were measured with electrochemical techniques. During the friction phase, when the surface will be activated, the open circuit potential breaks down. When the friction stops, the OCP increases. Between the movement phases, measurements of critical pitting potential were done. Thereby the quality of repassivation was investigated. The tests were done in a 3\% sodium chloride solution. Different temperatures were tested as well as the influence of air saturation and low oxygen content.}, language = {en} } @inproceedings{SorgSchulerHoertnagletal., author = {Sorg, Matthias and Schuler, Philipp and H{\"o}rtnagl, Arnulf and G{\"u}mpel, Paul}, title = {Gemeinschaftlich durchgef{\"u}hrter Workshop mit Fachvortr{\"a}gen zu Korrosions- und Schadensmechanismen an Schutz- und Barrieresysteme bei hochfesten Stahlnetzen}, abstract = {13.10.2017, Geobrugg AG, Davos, CH}, language = {de} } @misc{BogatzkySorgGuempel, author = {Bogatzky, Torsten and Sorg, Matthias and G{\"u}mpel, Paul}, title = {Schadensanalytik an Bauteilen aus nichtrostenden St{\"a}hlen}, series = {TAE-Seminar "Rostfreie St{\"a}hle - Konstruktions- und Verarbeitungshinweise", 14.09.2017, HTWG Konstanz}, language = {de} }