Mechanical properties and fatigue behavior of railway wheel steels as influenced by mechanical and thermal loadings

• In the current work the deterioration of mechanical properties of railway wheel steels (UIC ER7T and ER8T) is in focus. These are medium carbon steels (∼0.55 wt.% C) heat treated to a near pearlitic microstructure with some 5-10% pro-eutectoid ferrite. During operation of trains, high thermal loads are evolved because of recurring acceleration, braking, curving and occasional slippage. It is thus relevant to examine the high temperature performance of wheel material and evaluate the decrease in strength after thermal exposure as well as the degradation of fatigue properties. Samples were extracted from virgin wheels and pre-strained to around 6.5% strain as well as cyclically deformed, to also account for the change in properties that is induced by plastic deformation inherent in the wheel tread surface. Both un-deformed and pre-strained material was heat treated for different times in the temperature range of interest, from 250°C to 600-700°C. Hardening was observed in both conditions around 300°C followed by softening at higher temperatures. Spheroidization of the pearlite started to become visible at 450°C for the un-deformed material and at around 400°C for the pre-strained.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Annan materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Other Materials Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Carbon

Carbon steel

Deformation

Mechanical properties

Pearlite

Railroads

Vehicle wheels

Fatigue behavior

Fatigue properties

High temperature performance

Medium-carbon steels

Pearlitic microstructure

Railway wheel steels

Temperature range

Thermal exposure

Wheels

Materialteknik

Materials Engineering

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