Structure and properties of railway wheel surface after restoration surfacing and service loading

Abstract

Presented are the investigations of effect of composition of surfacing consumables on structure and phase composition of deposited metal of surfacing zones (surface, fusion line, HAZ) in restoration of railway wheels from grade 2 steel. Information received at different structural layers (from grain to dislocation) was used for analytical estimations of effect of parameters of forming structures on mechanical properties (σ0.2, K1c) of railway wheels, reconstructed by surfacing, before and after operation. Role of structural factors in change of level of local internal stresses τl.in, i.e. sources of crack formation in subsurface layers of deposited metal, was investigated. It is determined that surfacing consumables of bainite and bainitemartensite classes provide for high indices of mechanical properties and crack resistance of railway wheels after restoration repair and operation. 9 Ref., 1 Today problem of increase of service reliability and life of machines, mechanisms, parts etc. becomes more and more relevant. This problem is particularly critical for separate heavy loaded basic parts and mechanisms of running gear of cars and engines, main element of which is a wheel having direct contact with rail. Surface of wheel flange is subjected to the most significant wear in process of operation. Regardless different technological developments of restoration repair, problem of strength, reduction of wear level and crack resistance of railway wheels [1-3] is still relevant.In relation to restoration surfacing of surface of wheel flange, the authors carried out preliminary examinations of structural-phase changes in metal close to the roll surface of railway wheels [4]. Role of each of structural factors (phase constituents, grain, subgrain and dislocation structures, phase precipitates etc.) in change of strength and crack resistance of metal of railway wheels was investigated based on obtained results. The results of experimental investigations, received at different structural levels, i.e. from macro (grain) to micro (dislocation), made a basis for performance of analytical estimation of specific (differential) input of separate structural-phase factors and parameters in change of general (integral) value of mechanical characteristics, namely strength σ 0.2

Railway Vehicle Wheel Restoration by Submerged Arc Welding and Its Characterization

“…For the above reasons and sustainable development, overlay welding has been widely used in industry to extend the lifetime of the worn-out parts, and/or to protect the wear of machine parts such as valve seat ring [1], chisel ploughshare [2], excavator teeth [3,4], pipeline valve [5], crane wheel [6,7], turbine blade [8], railway wheels [9,10], etc. Plasma transfer arc welding, gas metal arc welding, laser beam welding, and submerged arc welding are used for overlay welding [11].…”

“…When the cooling rate was lowered from 33 • C/s to 11.1 • C/s, martensitic content in the heat affected zone decreased; the volume fraction of ferrite-pearlite component increased; and the bainite content was stabilized. Markisha et al [10] studied the effect of welding wire composition on microstructure and mechanical properties. Using welding wire with C 0.12 wt.%, Mn 1.0, Si 0.35, Cr 0.67, Ni 0.8, V 0.1, Mo 0.4, a weld metal composed of bainitic and martensitic phases was obtained, and that composition gave the weld metal relatively higher yield strength and fracture toughness.…”