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Austube Mills’ C450PLUS® structural tube has the strength of 450 Grade with the elongation, formability, weldability and processing capabilities of 350 Grade. Available in RHS, SHS and Silo Tube, C450PLUS complies with the requirements of both the commonly specified lower strength 350 grade and the structurally efficient higher strength 450 grade, providing a lower cost product to the specifier and end-user.


  • Higher strength for the same weight = more efficient design
  • More efficient design = lower total cost
  • Recognised in Green Star® = greater asset owner value
  • Same elongation as C350L0 = no loss of ductility and workability
  • Test certificate and in-line marking = guarantees compliance and quality
  • Complies with AS/NZS 1163 : 2016 C450L0 = reduce risks, increase structural integrity
  • Manufactured in Australia = Supported by an Australian Company

C450PLUS products comply with the requirements of two AS/NZS 1163 steel grades – The higher Grade C350L0 elongation requirements and the higher C450L0 requirements for both Yield and Tensile strength. Being fully compliant with AS/NZS 1163, C450PLUS products can be readily processed to Australian/New Zealand Standards and suit general, mechanical and structural fabrication processes, including welding and galvanizing.

  • Minimum Yield Strength: 450 MPa (a measure of how strong the tube is)
  • Standard designation: AS/NZS 1163: 2016 – C450L0
  • Steelmaking process: Fine-grain continuously-cast practice
  • Product manufacture: Cold-forming and high frequency Electric Resistance Welding (ERW) of steel strip. The cold-forming process enhances the strength, hardness and surface finish of the manufactured product.
  • Carbon Equivalence (CE): 0.43 as per C350L0 products
  • Welding Code Steel Type 7B (in Tables 4.6.1(B) of AS/NZS 1554.1 and AS/NZS 1554.5)
  • Mechanical properties: Tensile test and below for impact test requirements. For cold-flattening tests, AS 1163 requires deformation to 75% of initial tube depth
  • Impact Properties: Satisfies Clauses 15.2 and 16.2 of AS 1163 for Charpy V-Notch impact tests at the test temperature of 0°C (i.e. L0)