AD 507: Galvanizing steel of grade S460M

SCI has recently been asked whether the heating of thermomechanical rolled steel of grade S460M when subject to hot-dip galvanizing will affect the properties of the material. This Note addresses this issue in the context of the production and galvanizing processes.

The product standard for structural steel of grade S460M is BS EN 10025-4:2019. Part 4 is titled Technical delivery conditions for thermomechanical rolled fine grain structural steels.

The production process involves a rolling finish temperature of 700°C, lower than the typical rolling finish temperature of 750°C. The lower temperature requires a greater force to roll the material. The process produces a fine grain structure and a tough material which is designated by the letter M. The properties are retained unless the material is reheated above 650°C ⁽¹⁾.

Hot-dip galvanizing involves dipping the steel in a bath of molten zinc that commonly has a temperature of about 450°C ⁽²⁾. The immersion time is typically 4 to 5 minutes but can be longer in certain circumstances. The temperature of the galvanizing bath is therefore below that at which the properties of the steel would be affected.

Galvanizing steels with a yield strength above 650 MPa and steels of high hardness is addressed in SCI Publication P432 ⁽³⁾.

Contact: Richard Henderson
Telephone: 01344 636555
Email: advisory@steel-sci.com

(1) https://www.steelconstruction.info/Steel_material_properties
(2) The Engineers & Architects’ Guide: Hot Dip Galvanizing, The Galvanizers Association.
https://www.galvanizing.org.uk/publications/
(3) Baddoo, N, Chen A, High strength steel design and execution guide, (P432), SCI, 2020