Eco-efficient Transport
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| LATEST MODEL Stainless steel railway carriages, such as this of Japan Railways, offer two major advantages -- light weight for greater energy efficiency and high corrosion resistance for lower maintenance. |
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| INTERIOR COMPONENTS can also be made of the same material |
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All-stainless-steel railway carriages now account for half of all carriage production
in Japan
Nickel magazine, Mar. 02 -- Railway carriages constructed of S30103 stainless steel offer a
host of environmental advantages. If a single grade of stainless steel is used throughout the carriage,
recyclability is greatly enhanced. Stainless steel railway carriages are also considerably lighter than
carbon steel and even aluminum-alloy carriages. This means that less energy is required to move them, and so
the impact of energy production is significantly reduced. Reduced car and rail maintenance contributes to a
longer service life, thus reducing the life-cycle costs associated with the carriages.
Stainless steel was first adopted for railway carriages in Japan in 1958, with the introduction of U.S. technology. The stainless steel then adopted was 16% chromium, 4% nickel and 4% manganese. Carriages were made of ordinary carbon steel, with stainless steel used only for the body work.
The major desirable properties of structural materials for carriages are:
- large specific strength (strength per unit weight) for weight reduction;
- excellent workability and weldability;
- high corrosion resistance, particularly of weld; and
- good elongation.
With these objectives, Japanese steelmakers developed and perfected a new chemical composition during the 1970s consisting of 17% chromium, 7% nickel and 0.030% carbon that became known as S30103. The new composition rendered the steel stronger during cold fabrication and avoided the lower corrosion resistance associated with welds.
The application of S30103 enables the manufacture of structural members of various configurations, required for the carriage structure. Different mechanical properties can be achieved through annealing and temper-rolling, and surface finishes similar to those of conventional stainless steels are available, thus meeting decorative requirements.
Along with the advantageous design, all the carriages' components were made of stainless steel. The replacement of all carriages on the Yamanote Line, the busiest loop in Tokyo, with stainless steel units was completed in 1984, and since then, stainless steel carriages have become the mainstay of commuter lines in Japan.
The latest type of stainless steel carriages meets all performance requirements, such as strength, rigidity, fire and heat resistance, and durability. Also, these stainless steel carriages are 20% lighter in weight than ordinary carbon steel carriages and 3% lighter than aluminum carriages.
Stainless steel is a recyclable material which places a minimal burden on the environment, and it has the added advantages of being strong, corrosion-resistant and durable. Accordingly, stainless steel is gaining high marks as an "eco-product" with considerable economic and environmental advantages:
- The lighter weight results in a large reduction in energy consumption, especially by commuter trains, which start and stop frequently.
- The high corrosion resistance of stainless steel requires no rust-preventive coating expenses and also provides longer service life.
- Rail maintenance costs are reduced because of the carriages' light weight.
- Stainless steel carriages composed of a single steel grade require no separation for recycling and can be 100% recycled.
Various technical hurdles in cost-effectively using S30103 are being overcome by Japanese steelmakers in conjunction with carriage builders. Among recent breakthroughs to reduce manufacturing cost is the use of laser welding, replacing spot welding. Laser welding also results in lower thermal distortion and gives a smooth weld with an attractive appearance.
Increasingly, steelmakers are focusing their research-and-development efforts on new welding technologies for the application of stainless steel in high-speed railway carriages requiring high air-tightness, such as the Shinkansen bullet trains.
Adapted with permission from an article that appeared in the November 2001 issue of Steel Today
and Tomorrow, published by Japan Iron and Steel Federation.
Photo: Japan Iron and Steel Federation
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Steel Today & Tomorrow Japan Iron & Steel Exporters' Association 3-2-10, Nihonbashi Kayabacho, Chuo-ku, Tokyo 103-0025, Japan Tel: 81 3 3669 4818 Fax: 81 3 3661 0798 Website: www.jisf.or.jp/about2/about01-e.htm |
