Introduction
Rails are a vital constituent of railways, and their performance is
directly linked to the safety of railways. Railway companies are
aiming to achieve relatively high transportation efficiency and tackling
propositions of relatively high-speed passenger and heavy haul
freight railways transportation. In line with these trends, the environmental
factors affecting rail usage are becoming harsher than
ever, and therefore, rails having relatively high performance are being
developed.1, 2)
A rail joint section with an offset is subjected to mechanical
shocks whenever a train passes, influencing the running stability of
the train. In order to alleviate such mechanical shocks, long rails
produced by welding rails are being installed across the world. Today,
the rail welding technology has become an extremely important
technology that is partly responsible for the safety of railways.
Further, the quality requirements for a weld section vary depending
on the type of railways. A considerable portion of the wheel rolling
contact surface at the weld section is required from the viewpoints
of running stability and riding comfort. In the case of freight
railways, wear and abrasion resistance and surface damage resistance
of the heat affected zone (HAZ) developed at a weld section, and fatigue
damage resistance of the rail web and the rail base are required
in order for the rails to withstand the heavy load exerted by the
wheels.
This report introduces four welding methods that have been developed
for welding rails, examples of the quality problem at the
weld section that has become overt in overseas freight railways, and
a new welder introduced to us as a part of the study on the solution
of such a problem.
IntroductionRails are a vital constituent of railways, and their performance isdirectly linked to the safety of railways. Railway companies areaiming to achieve relatively high transportation efficiency and tacklingpropositions of relatively high-speed passenger and heavy haulfreight railways transportation. In line with these trends, the environmentalfactors affecting rail usage are becoming harsher thanever, and therefore, rails having relatively high performance are beingdeveloped.1, 2)A rail joint section with an offset is subjected to mechanicalshocks whenever a train passes, influencing the running stability ofthe train. In order to alleviate such mechanical shocks, long railsproduced by welding rails are being installed across the world. Today,the rail welding technology has become an extremely importanttechnology that is partly responsible for the safety of railways.Further, the quality requirements for a weld section vary dependingon the type of railways. A considerable portion of the wheel rollingcontact surface at the weld section is required from the viewpointsof running stability and riding comfort. In the case of freightrailways, wear and abrasion resistance and surface damage resistanceof the heat affected zone (HAZ) developed at a weld section, and fatiguedamage resistance of the rail web and the rail base are requiredin order for the rails to withstand the heavy load exerted by thewheels.This report introduces four welding methods that have been developedfor welding rails, examples of the quality problem at theweld section that has become overt in overseas freight railways, anda new welder introduced to us as a part of the study on the solutionof such a problem.
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