Contact fatigue of TiCN coated sintered steels

Abstract

Investigation was focused on resistance of Astaloy CrL type sintered material to contact fatigue. The material in two versions (0·3 and 0·7 wt-%C) was covered with TiCN coating. The results show that resistance to contact fatigue increased substantially, up to the value of about 3410±90 MPa. This increase was influenced primarily by the properties of coating. In this case, the impact of the matrix was of secondary importance. The results obtained in the evaluation of life in terms of contact fatigue were confronted with those of the microscopic observation of generation and propagation of cracks leading to the formation of pitting, as well as with other tests. It describes the impact of contact fatigue stress to changes in the material at the point of application. A special section is devoted to the use of finite element method (FEM) for simulation of the Hertzian stress and changes during contact strain.

Applying “Spark Plasma Sintering” Technology to Enhance the Resistance to Contact Fatigue of Sintered Steel Based on Astaloy CRL

“…This result has to be confronted with results that have been achieved not only by us, on the material with the said contents of carbon, made in the traditional manner by way of cold pressing followed by sintering, both at the same sintering temperature of 1120 °C. The values published [1,2,11] As a result of rolling contact fatigue wear, pittings or craters have developed on the tested samples. Similar to the general observation regarding formation of pitting on sintered materials, even in this case several pittings have been developed in the wear orbit, as well.…”

“…Lubrication is ensured by a continuous supply and filtration of MOGUL SAE 80 gear oil. A more detailed description of this method is given in our previous publications [1][2][3].…”

“…At a later stage we used such kinds of technologies which affected only the surface layers critical in terms of contact fatigue destruction. Here, for example, belongs the technology of laser hardening, or methods of applying hard thin coatings such as TiCN type or DLC type respectively to the surface layers [4][5][6]. In all the cases they did improve resistance to contact fatigue destruction.…”

“…Our previous works [1][2][3] have already monitored the contact fatigue of sintered steels based on material type Astaloy CrL produced by Höganäs. They were investigating sintered materials with a density of about 7000 kg.m -3 using heat and chemical-heat treatment and based on known methods of enhancing the basic properties of sintered materials, of course.…”

Effect of TiCN Coating on Tribological Properties of Astaloy CrL Sintered Steel

“…Currently sintered materials are used as structural parts for production of certain machine parts. It is assumed (and the first results prove it) that the use of coating methods also improve specific properties of these materials, for example wear resistance, contact fatigue and so on [10][11][12].…”