Precautions

Use underwater or in flowing water

　In applications underwater or with frequent exposure to flowing water, the stable protective film layer that is characteristic of ZAM™ is difficult to form, so that sometimes ZAM™ may gather red rust early without showing superiority to hot-dip zinc-coated steel sheets. Be aware of this when using it in such applications.

Handling

・In order not to damage the coating surface, handle the product carefully and do not put any sweat or finger smudges on the surface.
・If the surface should become damaged, repair it.
・ Be careful when removing a coil band because the end of the coil could spring up as it unwinds.
・ Store products securely, so that coils do not tip over and stacked-up cut sheets do not topple.
・ Be careful to prevent water stains and dew condensation.　If packaging paper is damaged, repair it.

Processing

・If the surface is damaged during processing, it could adversely affect corrosion resistance and paintability. In particular, some types of lubricating oil may corrode the coating layer during press working. It is therefore necessary to check the type of lubricating oil to be used. When lubricant is used, perform degreasing or other post-treatment after the processing.
・As time passes, a steel sheet tends to harden, resulting in a decrease in workability. To avoid this, use the steel sheet as soon as possible.

Precautions to prevent galvanic corrosion

(1) Avoid direct contact with lead or copper (or copper ion drops)
(2) For metal fittings and attachments, use products made of stainless steel (SUS304) or aluminum or those which are painted or heavily coated with zinc for increased durability.
(3) When using ZAM™ in a salt-damaged or snow-covered area, use metal fittings and attachments made of a similar metal (aluminum, zinc-coated metal) or stainless steel insulated properly and treated with an anticorrosive (or a sealing material)
(4) In such applications as lightning conductors where corrosion is likely to occur, insulation tape or aluminum wire should be used.

(Source: Preventive measures of bimetallic corrosion of prepainted/zinc-based coated steel sheets: Hot-dip zinc-coated Committee, The Japan Iron & Steel Federation)

Precautions to prevent corrosion due to
contact with a preservative-treated or
termite resistant wood

ZAM™ should not be left in contact with wood containing preservative/ant repellant for an extended period of time. Wood and laminated wood treated with preservatives and ant-repellants (primarily copper-based agents) adversely affect corrosion resistance property of coated steel sheets and prepainted steel sheets. Therefore, where these steel sheets are likely to come in contact with wood materials (parts of the roofs including eaves, roof edges and joints for example), insulation underthatch (roofing stock or butyl tape) should be used for rust prevention and steel-wood direct contact should be avoided.

(Source: Preventive measures of bimetallic corrosion of prepainted/zinc-based coated steel sheets: Hot-dip zinc-coated Committee, The Japan Iron & Steel Federation.)

Welding

Material, coating weight, chemical conversion treatment, oiling

・Select steel grade, coating weight, and chemical treatment to fit your application. Apart from the type of chemical treatment, you can choose either antirust oiling or no oiling. Oiling is recommended to minimize lubrication during press processing, soiling, and scratching. Oiling is necessary when no treatment is made.

Size

・Design according to the production range described in this catalog. Contact us beforehand if your conditions for use require more stringent specifications. Please consult us for sizes outside the range.

Product Shapes

・Choose either mill edge or slit edge according to your application. Also, choose either coils or cut sheets according to your cutting and processing conditions. From the standpoint of promoting continuous, automated operations and optimizing yield, it is recommended to use coils. When using coils, be aware that sometimes defective parts may be mixed in (because such parts cannot be removed by the inspection).

Inside diameter and outside diameter

・In the case of coils, specify the inside diameter and outside diameter to fit the specifications of your equipment. In specifying the inside diameter, allow for possible buckling in inner laps of the coil depending on the sheet thickness.

Packing mass

・Specify the packing mass according to handling capacity, etc. For coils, specify the maximum mass (if necessary, the minimum unit mass). The greater the mass, the easier the operation will be.

Applications and processing methods

・Quality control better suited to your application and processing method can be applied if relevant information is timely provided.

Overview

・It is known that with the passage of time, hot-dip zinc-coated steel sheets are subject to what is called darkening, namely, decrease in surface glossiness. ZAM
ZAM™ may also suffer discoloration as with other hot-dip zinc-based alloy coated steel sheets.

What is darkening?

・Darkening is a phenomenon in which the steel sheet appears gray due to the presence of a very thin oxide film on the zinc surface layer. In hot-dip hot-dip zinc-coated steel sheets, a very thin oxide film whose principal component is ZnO is formed on the zinc coating surface layer even immediately after manufacturing, and it has the property of changing and growing as time passes. From our experience to date, we infer that this phenomenon of darkening occurs by the following mechanism.
① An oxide film grows
↓
② The structure and thickness of the oxide film change
↓
③ The changed state of ② causes a change in the optical absorption coefficient
↓
④ The surface takes on a gray appearance

Characteristics of darkening

・In hot-dip zinc-based alloy coated steel sheet the zinc surface layer is covered with a very thin oxide film (mainly composed of ZnO). But the rate at which the oxide film changes and grows varies depending on such conditions as the structure and composition of the material as well as environmental factors, and the time until darkening becomes noticeable varies.
This darkening is unavoidable, but it is known to occur more readily under conditions of high temperature and high humidity.
Darkening is just an oxidation phenomenon on the zinc coating layer, thus the product quality is normal except for its gray appearance.
・This phenomenon develops when this material is stored either in the form of coil or cut sheet. It is therefore recommended to use the product as early as possible.