Effect of Mg on Inclusion and High Cycle Fatigue Behavior in Titanium Microalloyed Beam Steel

Abstract

In this paper, the fatigue behavior of titanium microalloyed beam steels were studied by high cycle fatigue test and fatigue crack growth rate test. The effect of Mg addition on the fatigue behavior in titanium microalloyed beam steel was systematically analyzed. According to the experimental results, the addition of magnesium can effectively modify the inclusions by reducing the size of Al2O3 and TiN and promoting the formation of finer complex inclusions with a MgO·Al2O3 core in titanium microalloyed high-strength beam steel. Inclusion number of the experimental steels had far less of an impact on the fatigue characteristic than inclusion size. With the heterogeneous nucleation effect of MgO·Al2O3, the inclusions are refined after the Mg addition. Beam-2 steel’s tensile strength decreased by approximately 54 MPa, while its fatigue strength increased by about 33 MPa, showing favorable fatigue resistance. These findings are essential for optimize the fatigue properties of titanium microalloy steel and promote the development of automobile beam steel with excellent fatigue properties.

Effect of Mg Addition on Inclusions in the Welding Heat-Affected Zone of Pressure Vessel Steels

“…This shows that the addition of Mg elements promotes the formation of fine inclusions in the experimental steel welding HAZ to a certain extent under the present experimental conditions. Combining the results of related studies [28,29], it could be deduced that when the area of inclusions is less than 5 µm 2 , it is the most suitable size of inclusions to play the role of pinning grain boundaries and inducing IAF nucleation. These are called the effective inclusions.…”