ISO 6158:2018

Overview

ISO 6158:2018 - Metallic and other inorganic coatings - Electrodeposited coatings of chromium for engineering purposes - specifies requirements for electroplated (electrodeposited) metallic chromium coatings, with or without undercoats, on ferrous and non‑ferrous metals used in engineering applications. The standard defines how coatings are designated (including basis metal, undercoats, type and coating thickness) and sets out inspection, sampling and testing requirements to ensure functional performance.

Note: the standard acknowledges common use of hexavalent chromium plating solutions and contains a safety warning; users must follow applicable health, safety and environmental rules.

Key topics and technical requirements

• Designation and ordering information: clear format to specify basis metal, alloy, heat‑treatment needs, type/thickness of undercoats and chromium layers, and post‑treatments (e.g., hydrogen‑embrittlement relief).
• Performance characteristics: requirements and tests for thickness, hardness, adhesion, porosity, appearance and surface finish.
• Special treatments: guidance on stress‑relief heat treatment prior to coating, hydrogen‑embrittlement‑relief post‑treatments, and peening requirements.
• Use of undercoats and multilayer systems: when nickel or other undercoats are recommended to improve corrosion resistance or to build up worn parts.
• Sampling and test methods: references to thickness measurement and porosity test methods and sampling procedures for inspection by attributes.
• Surface roughness and structure: provisions for specifying final surface roughness or engineered profiles (e.g., oil‑retaining, microporous or microcracked finishes).

Practical applications

Electrodeposited chromium coatings covered by ISO 6158 are applied where durable, engineered surfaces are required:

• Improve wear and abrasion resistance (shafts, pistons, slides)
• Reduce friction, fretting and galling on mating parts
• Restore or build up undersize/worn components
• Enhance corrosion resistance when combined with suitable undercoats or alloying
• Provide engineered surface profiles (oil‑retaining or non‑stick finishes)

Typical users include plating processors, design engineers, OEMs, procurement/specification writers, quality/inspection teams, and maintenance engineers in industries such as automotive, aerospace, heavy equipment, hydraulics and tooling.

Related standards

ISO 6158 references and aligns with other ISO standards relevant to plating and testing, for example:

• ISO 1463, ISO 2064, ISO 3497 (thickness measurement methods)
• ISO 4516 (microhardness testing)
• ISO 9227 (salt spray corrosion testing)
• ISO 9587 / ISO 9588 (pre‑ and post‑treatment for hydrogen embrittlement)
• ISO 4526 (nickel electroplating for engineering purposes)

Keywords: ISO 6158:2018, electrodeposited chromium, chromium plating, metallic chromium coatings, coating thickness, corrosion resistance, hydrogen embrittlement, adhesion, porosity.