ISO 4289:2023

INTERNATIONAL ISO
STANDARD 4289
First edition
2023-02
High velocity oxygen fuel (HVOF)
cermet coatings for metallurgical
roll components — Guidance with
requirements
Revêtements de cermet par pulvérisation oxycombustible à grande
vitesse (HVOF) pour les composants de rouleaux métallurgiques —
Recommandations et exigences
Reference number
ISO 4289:2023(E)
© ISO 2023

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ISO 4289:2023(E)
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© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
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ISO 4289:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Recommended HVOF cermet coating materials for various metallurgical rollers .2
5 Preparation of HVOF cermet coatings for various metallurgical rollers .2
5.1 Pre-treatment of various metallurgical components . 2
5.2 HVOF spraying . 3
5.3 Post-process of HVOF sprayed coatings . 3
6 Coating quality and performance evaluation . 3
6.1 General . 3
6.2 Coating quality . 3
6.3 Performance evaluation of coatings . 4
6.3.1 Thickness . 4
6.3.2 Surface roughness . 5
6.3.3 Bonding strength . 5
6.3.4 Porosity . . . 5
6.3.5 Microhardness . 5
6.3.6 Friction and wear test . 6
6.4 Sealing treatment of coatings . 9
Bibliography .11
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ISO 4289:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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This document was prepared by ISO/TC 107, Metallic and other inorganic coatings.
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ISO 4289:2023(E)
Introduction
Metallurgical rollers are the key components used in the steel industry. However, rollers considered
to be consumables with premature failure often occurring on the roller surface. The surface quality
of rollers determines the quality of products and also affects production efficiency. High velocity
oxygen fuel (HVOF), as an environmentally friendly technology, has become a promising technology
for improving the surface quality of rollers, thus extending the service life. Up until now, HVOF cermet
coatings (e.g. tungsten carbide based, chromium carbide based) have been widely used in various
rollers (e.g. hot dip galvanized line, continuous annealing furnace) in the metallurgical industry around
the world. In the process of metallurgical production, the specific coating is determined by the working
conditions of the rollers used.
This document aims to promote the technical progress of the industry.
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INTERNATIONAL STANDARD ISO 4289:2023(E)
High velocity oxygen fuel (HVOF) cermet coatings
for metallurgical roll components — Guidance with
requirements
1 Scope
This document specifies recommendations and requirements for the selection of coating materials, the
pre-treatment of rollers, the preparation and post-treatment of the coatings, as well as the quality and
performance evaluation of high velocity oxygen fuel (HVOF) cermet coatings used on metallurgical roll
components.
This document is applicable to four metallurgical rollers: pot inner roller (sink/stabilizing roller) of
continuous galvanized line (CGL), cold rolling process roller, hot-rolled straightening roller and furnace
roller.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 14921, Thermal spraying — Procedures for the application of thermally sprayed coatings for
engineering components
ISO 14916, Thermal spraying — Determination of tensile adhesive strength
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
pot inner roller (sink/stabilizing roller) of continuous galvanized line
pot inner roller (sink/stabilizing roller) of CGL
roller that ensures the stable flow of the steel strip into the zinc pot
3.2
cold rolling process roller
main working part of the sheet mill, which determines the quality of the rolled material and the
production efficiency of the mill
3.3
hot-rolled straightening roller
core part of the hot rolling strip mill, which is composed of six rollers
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ISO 4289:2023(E)
3.4
furnace roller
key part of a continuous annealing furnace in the continuous strip production line
Note 1 to entry: The quality of the furnace roller directly affects the surface quality of strip steel.
4 Recommended HVOF cermet coating materials for various metallurgical
rollers
The appropriate coatings for the pot inner roller (sink/stabilizing roller) of CGL, cold rolling process
roller, hot-rolled straightening roller, and furnace rollers should be as given in Table 1. Generally, the
damages to rollers include corrosion, wear, high-temperature oxidation, etc. The recommendation of
coatings is determined by the failure of the rollers, as shown in Table 1.
Table 1 — Failures and recommended coating materials for various metallurgical rollers
Rollers Failures Example of Powder Particle
recommended manufactur- size
Corrosion Wear Oxidation Accumulation
coatings ing methods
of tumours
Pot inner
roller (sink/
√ √ / √ WC-xCo
stabilizing
roller) of CGL
Cold rolling
√ √ / / WC-xM(NiCr, Co)
process roller
Hot-rolled
straightening / √ / / WC-xCo Agglomerated −45 μm
roller and sintered +15 μm
Furnace roll-
ers (500 °C to / √ √ √ Cr C -xNiCr
3 2
700 °C)
MCrAlY(M = Ni/
Furnace roll- Co/NiCo) + oxides,
/ √ √ √
ers (≥800 °C) carbides or bo-
rides
Key
√ : possessing this failure form
/ : there is no such failure form
x : mass fraction of the metallic phase, which should be controlled within a mass fraction of 10 % to 50 %
5 Preparation of HVOF cermet coatings for various metallurgical rollers
5.1 Pre-treatment of various metallurgical components
The surface of the rollers should be inspected and reviewed to ensure their suitability before spraying.
These procedures should be followed for the pre-treatment and surface preparation of the metallurgical
components:
a) It is necessary to remove the impurities generated during the production process to obtain a clean
surface. For the pot inner roller (sink/stabilizing roller) of CGL, the residuary zinc on the surface
should be removed by dilute acid solution, using the following steps:
1) Preparation of dilute acid solution: The concentration of sulphuric acid mass percentage should
be controlled within 3 % to 7 %.
2) Immersion: The dipping time of zinc removal treatment should be controlled within 6 h to 72 h.
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ISO 4289:2023(E)
3) Cleaning: The sinking/stabilizing rollers together with the special lifting frame should be
cleaned by soaking and rinsing.
4) Airing: After soaking and rinsing, the workpieces should be together with the special lifting
frame on the fixed pit position to dry.
b) The roller surface should be inspected to ensure that there are no defects or cracks on the surface.
If shrinkage cavities, pores and sand holes are present, their size should be smaller than 0,5 mm. If
there are cracks or defects with a size larger than 0,5 mm, partial substrate from the roller surface
should be carried out by a carbide tool head. Pits larger than 3 mm in diameter shall not be present
on the roller surface after processing. The surface roughness should be lower than 3,2 μm.
c) Prior to spraying, grinding and polishing should be carried out to obtain a surface of which the
roughness is lower than 0,8 μm. To enhance the adhesion of coatings to rollers, sandblasting is
employed to roughen the working surface.
5.2 HVOF spraying
HVOF spraying shall be operated in accordance with ISO 14921.
5.3 Post-process of HVOF sprayed coatings
There should be a post-process inspection and operation of HVOF sprayed coatings, including sealing
pores, heat treatment and dynamic/static balance.
The inspection of the coatings should be carried out after spraying via measurement of thickness,
roughness, microhardness and bonding strength.
Thermal spraying sink/stabilizing rollers and furnace rollers should be sealed. Once spraying is
finished, seal the pores as soon as possible. For sealing, a range of different sealants and procedures are
available and the supplier’s instructions should be followed.
6 Coating quality and performance evaluation
6.1 General
The perform
...