In Mitsubishi Steel Muroran Inc., there are two main plants, one is steel making plant which is utilizing both electric furnace and ladle furnace with out-of-furnace refining process and up-to-date bloom continuous caster, etc., and the other is rolling plant which has in-line high speed forging press providing a higher forging effect, and has V-H bar mill with high rigidity and automatic tension control. These equipment can produce special steel bars with low cost and high quality in a high productivity.


Special Steel Bar

Carbon steels, Low-alloy steels, Non-heat treated steels, Spring steels, Nitriding steels, Bearing steels, Free-cutting steels, Other types of special steels

Categories by Product

Hot-Rolled Special Steel Bars for Construction Machinery Parts

Construction machinery must withstand usage far more demanding than an automobile. Hot-rolled special steel bars used for their parts must have high strength and durability.

Swing Bearing

Special steel bars used for industrial machinery

Various special characteristics such as high mechanical strength, high precision etc. are demanded for special steel bars used as parts of machine tools and working machines. The company manufactures special-purpose special steel bars to meet the diverse needs.

<For Machine Tools>Ball screws/Linear Guides
<For Injection Molding Machine>Tie Bars

Hot-rolled Special Steel Bars for Automotive Parts

Modern automobiles are being made lighter with lower fuel costs, in an effort to protect the environment. Our highly trusted special steel bars are used for vital automotive parts such as the engine, power train and suspension.

Crankshaft, connecting rod, camshaft
Pinion Gear

Non-heat Treated Steel Series

"non-heat treated steel series, " which are only hot-rolled and forged, have the same designated mechanical characteristics as if they were processed in the quench and the draw furnace. These products make our customer's options more flexible, depending on the required level of usage and strength. As a result, they also contribute to reduce number of processes.

  • Non-heat Treated Steel for Machining
    • Ferrite & Pearlite Steel Series (SMT Series)
      (Usage) Cylinder Rod, Pin, and others
  • Non-heat Treated Steel for Forging
    • Ferrite & Pearlite Steel Series, Bainite Steel Series (VMC Series)
      (Usage) Crankshaft, Connecting rod, Yoke, Rod head, and others
Hydraulic Pressure Cylinder
Rod Head

Manufacturing Process for Special Steel Bar

Endeavor to Pursue Better Quality of Product
New challenge to higher quality Mitsubishi Steel is a pioneer in the world to produce structural steels for automobile through LF (Ladle refining furnace) Degassing-Bloom continuous casting process and left mark on quality improvement. Now, Mitsubishi Muroran is trying higher quality and productivity improvement in addition to saving energy to produce earth environmental friendly special steels through compounding pig iron with scrap.

Refining process

RH Degassing

The refining process is performed in ladle refining and RH degassing. Its combination can make flexible control of chemical composition and melting temperature. Additional process of dehydrogen and deoxidation can make refined melting steel extreme pure steels with less non-metal inclusion for next process of continuous bloom casting.

Bloom continuous caster

The bloom continuous caster is designed to be able to produce bloom casting with large size cross section, which is superior internal and surface quality.

2,500ton in-line Press

The forging press is installed in the bloom rolling process to forge cast blooms for enhancing internal quality, as well as to reduce cutoff for improve yield rate.

Full continuous V-H rolling machine

The machine rolls high dimensional accuracy steel bars fully automatically according to high rigidity full continuous V-H low-tension rolling system.

Distribution Network

We promptly respond to customer needs with our network and

Indonesia Project

In Indonesia, an integrated production model, which covering materials to products, was established through synergy between Springs business and Special Steel business. Fully utilizing this model, we strive to expand the sales of cost-competitive leaf springs worldwide. We will also promote sales of special steel with a focus in Southeast Asia, and seek to further expand same business model in North America and India in future.