The use of stainless steel material for railway

The use of stainless steel for trains goes back nearly three quarters of a  century. It was durability and ease-of-maintenance considerations that tipped  the balance towards stainless steel. With design lives of often more than 40  years, the application of stainless steel for train carriages was a highly  worthwhile choice, due to the corrosion-resistant characteristics of the steel.

Over the years, rail technology has developed – and so has stainless  steel. The refinement of metallurgical processes has further improved the  uniformity and corrosion-resistance of proven chromium-nickel stainless steels.  The range of mechanical treatments to further enhance their mechanical  properties has been extended. New grades have been developed, including  chromium-manganese types, which combine cost reduction with high mechanical  strength. Ferritic stainless steels have given rail manufacturers new and  particularly cost-effective options.

 Invented in the early 20th century, stainless steels were soon applied to the rail industry. The 1930’s brought widespread use of stainless steel for  rail coach bodies. Weight reduction became a priority and laid the ground for  levels of speed and comfort that had not been experienced before. Especially in  North America, stainless steel became the preferred material for rail coaches.

  Although stainless steel is neither the lightest of materials nor the  least expensive, both manufacturers and operators soon discovered that its  outstanding long-term corrosion resistance provided maintenance and cost  advantages. The fact that painting became redundant made stainless steel even  more attractive. However, it was also a marketing issue. Long-distance rail  travel was positioned as a modern, technologically advanced option for the  demanding customer and stainless steel was an icon for this idea.

  Much of the enthusiasm for stainless steel has been maintained over the  decades, both for technical reasons and as a matter of aesthetic preference.  Stainless steel is equally present in metro, commuter and long distance-trains  to the present day. In many parts of the world, notably in North America, early  experiences with stainless steel have influenced the preference of railway  operators, rail-coach manufacturers and passengers alike. Unpainted, profiled  stainless steel panels continue to be the “normal” material.

 Besides aesthetic criteria, safety considerations are increasingly taken  into account. Although serious collisions are very infrequent these days,  higher operating speeds increase the likelihood of injury when they do occur.  Many rail companies have therefore chosen to construct carriages from  austenitic stainless steel, in preference to alternative materials such as  carbon steel and aluminium alloys. This choice carries a unique safety-related  benefit. First and foremost to the high energy absorption made possible by the  unique work-hardening properties of austenitic stainless steels. If the  assembly is properly designed, stainless steel tubular sections will fail in  compression – not in buckling. The inherent material strength increases as the  speed and intensity of the deformation increases, thus maximising energy  absorption.

  Stainless steel is so widely used, and the application of it in railways is a prime example of how the stainless steel has created beneficial impacts  like reducing weight and increasing speed and safety aspects, increasing the  overall practicality of rail lines.

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