An Effect of Laser Hardening on Contact and Bending Fatigue of a 42CrMo4 Steel

Abstract

The paper deals with an investigation of surface laser hardening characteristics on contact and bending fatigue resistance of a 42CrMo4 steel, being often used for manufacture of gear wheels. The aim of the experimental programme was to simulate the complex service loading of fairly large gears by two separate investigations, namely contact fatigue performed on a special, so called analogon machine and bending fatigue performed on high cycle fatigue resonance machines using three-point-bend (3PB) fairly large specimens. It was shown that after optimising the methodology and parameters of the laser hardening technology, contact fatigue resistance is very good, comparable with very expensive and time consuming thermochemical high-depth surface treatments. Bending endurance limit can be increased. The role of residual stresses resulting from the laser treatment was shown as decisive.

Fatigue crack growth of 42CrMo4 and 41Cr4 steels under different heat treatment conditions

“…Commonly used steels like 41Cr4 and 42CrMo4 steels are representative materials subjected to heat treatment. The mentioned type of steels are often used as a structural elements subjected to the cyclic loading conditions such as axle or gear shafts, connecting rods, elevator links and pins (Das et al, 2015;Henschel and Krüger, 2016;Černý et al, 2012). The 41Cr4 steel has been extensively used in automotive applications.…”

“…Another factor playing important role is the surface of the element. Multiple researches were conducted (Černý et al, 2012;Lanzutti et al, 2017) in order to examine influence of what surface finish is the most efficient for elements working under fatigue loading. Additionally, some of surface modifications are examined in order to improve elements' fatigue properties (Černý et al, 2012).…”