Steel for wheel

Abstract

There is provided steel for wheel having a chemical composition consisting of, by mass percent, C: 0.65 to 0.84%, Si: 0.02 to 1.00%, Mn: 0.50 to 1.90%, Cr: 0.02 to 0.50%, V: 0.02 to 0.20%, and S: 0.04% or less, in which 34≦2.7+29.5×C+2.9×Si+6.9×Mn+10.8×Cr+30.3×Mo+44.3×V≦43, and 0.76×exp(0.05×C)×exp(1.35×Si)×exp(0.38×Mn)×exp(0.77×Cr)×exp(3.0×Mo)×exp(4.6×V)25, the balance being Fe and impurities, and the impurities containing P: 0.05% or less, Cu: 0.20% or less, and Ni: 0.20% or less. This steel for wheel is excellent in balance between the wear resistance, rolling contact fatigue resistance and the spalling resistance, and can give a long life to the wheel.

Description

TECHNICAL FIELD[0001]The present invention relates to steel for wheel. More particularly, the present invention relates to steel for wheel that is suitable as a material for a high-hardness wheel for railroad, the material being excellent in wear resistance, rolling contact fatigue resistance, and spalling resistance.[0002]Spalling is a phenomenon that a portion of wheel, when heated and rapidly cooled by emergency braking or the like, is transformed into brittle martensite called a white layer, from which a crack propagates, and the white layer is subjected to brittle fracture and peels off. This phenomenon is also called a “thermal crack” in some cases.BACKGROUND ART[0003]In recent years, with a worldwide increase in running distance and loading capacity, a wheel for railroad (hereinafter, also referred to as a “wheel”) having a service life longer than before has been demanded.[0004]There are three phenomena that mainly cause damages to a wheel: (i) wear, (ii) rolling contact fat...

AI Technical Summary

Benefits of technology

The present invention provides a steel for wheel that has excellent balance between wear resistance, rolling contact fatigue resistance, and spalling resistance. This results in longer life for the wheel. The steel has been tested and compared to the standard steel used for railway wheels, and has shown significant improvements in wear resistance, rolling contact fatigue life, and resistance to spalling. This makes it ideal for use in harsh environments with increased running distance and loading capacity.

Problems solved by technology

There are three phenomena that mainly cause damages to a wheel: (i) wear, (ii) rolling contact fatigue, and (iii) spalling.

Especially in recent years, an increasing number of wheels have been damaged by wear resulting from the increase in running distance and by rolling contact fatigue resulting from the increase in loading capacity.

Empirically, it is known that the wear resistance and the rolling contact fatigue resistance are properties that are incompatible with the spalling resistance.

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