Submersibles of casted maraging steel

Olavi Piha*, Tanja Saarelainen, Juhani Orkas

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


In 1982, the Soviet Union Academy of Sciences enquired whether a Finnish company Rauma-Repola would be interested in manufacturing two research vehicles capable of diving to a depth of 6 kilometres. The contract was signed on May 1985 and the vehicles signed off into service in December 1987. The most critical challenge was to determine how the personnel's spheres could be formed as they were required to protect personnel from pressures reaching 600 bar. Maraging steel was finally selected as the material for their construction. Large parts had never before been poured in this material. The foundry developed ultra-high strength MVD steel for the manned sphere. This material contained low level of impurities and underwent a specific heat treatment to attain the required properties: Yield strength Re 1650 N/mm2, Tensile strength Rm 1730 N/mm2, Elongation A5 6 %. The chemical analysis was C < 0.02 %, Ni 17-19 %, Mo 4-6 %, Co 10-13 %, Ti < 0.35 %. Those values can only be reached using vacuum technology.

Original languageEnglish
Title of host publication72nd World Foundry Congress, WFC 2016
Number of pages2
ISBN (Electronic)9781510833128
Publication statusPublished - 2016
MoE publication typeA4 Article in a conference publication
EventWorld Foundry Congress - Nagoya, Japan
Duration: 21 May 201625 May 2016
Conference number: 72


ConferenceWorld Foundry Congress
Abbreviated titleWFC


  • Centerline shrinkage
  • Steel foundry
  • Tevo Lokomo Ltd.
  • Ultra-high strength maraging steel
  • Vacuum technology


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