Adjusting the friction response of the wheel-rail interface is a key factor in the mitigation of wear and rollingcontact fatigue (RCF) in rails. The use of top-of-rail (TOR) friction conditioners has the potential to reduce maintenance costs significantly. Unfortunately, conflicting results on the use of commercial TOR conditioners have been presented in the literature. In this work, the performance of commercial TOR conditioners and a laboratory-made formulation were tested, both on the lab scale and in field measurements. Friction results are discussed together with the structural and chemical analysis of the tested materials.
Pitting susceptibility of metastable austenitic stainless steels as a function of surface conditions
(2019)
The influence of surface roughness and local defects on pitting susceptibility of type 304 (UNS S30400) and type 301 (UNS S30100) in chloride solution were investigated. Because the mechanical properties can be regarded as decisive for the achieved surface quality, different properties of the base material were obtained by cold rolling the metastable austenites. This was done before the surfaces were finished. Therefor the surfaces were treated by different grinding parameters to generate different surface conditions and different defects. As a reference, different standardised surface finishes were used.
By using and comparing different methods for the characterization of surface roughness and surface texture, it is possible to find a relationship between the quantity and characteristics of local defects on the one hand and pitting susceptibility on the other hand. For the machining parameters used, a ranking of the influencing factors on the corrosion resistance achieved could be determined.
The automated application of software-based solutions for estimating the pitting susceptibility of machined surfaces and components will be discussed using concrete examples.
Pitting susceptibility of metastable austenitic stainless steels as a function of surface conditions
(2019)
Fachvortrag auf der 10th International European Stainless Steel Conference and 6th European Duplex Stainless Steel Conference (ESSC & DUPLEX 2019), 30.09. – 02.10.2019, Vienna, Austria
This paper compares the surface morphology of differently finished austenitic stainless steel AISI 316L, also in combination with low temperature carburization. Milled and tumbled surfaces were analyzed by means of corrosion resistance and surface morphology. The results of potentiodynamic measurements show that professional grinding operations with SiC and Al2O3 always lead to a better corrosion resistance of low temperature carburized surfaces compared to the untreated reference in the used acidified chloride solution. Big influence on the corrosion resistance of vibratory ground or tumbled surfaces has the amount of plastic deformation while machining, that has to be kept low for austenitic stainless steels. Due to the high ductility, plastic deformation can lead to the formation of meta stable pits that can be initiation points of corrosion. The formation of meta stable pits can be aggravated by low temperature diffusion processes.