ASTM F3019/3019M Chrome Free Zinc Flake Coated Fasteners
ASTM F3019/3019M specification covers the basic requirements for non-electrolytically applied zinc-flake composite corrosion protective coating systems for fasteners. The coating systems do not contain hexavalent chromium, lead, cadmium,
or mercury.
ASTM F3019/3019M specification is intended for corrosion protection of inch and metric series threaded fasteners with minimum nominal diameters of 0.250 in. for inch series and [6.00 mm] for metric as well as for non-threaded fasteners
such as washers and pins. ASTM F3019/3019M coating system may be specified to consist of a zinc-flake basecoat, or a zinc-flake basecoat and topcoat.
For threaded fasteners, the coating system will typically consist of a zinc-flake basecoat and topcoat.
The basecoat is a Zinc Rich material containing aluminum flakes dispersed in a compatible liquid medium. The zinc-flake basecoat may be specified to contain integral lubricant. Topcoats may be organic or inorganic in composition depending upon the specified requirements. Organic topcoats consist of polymer resins, aluminum, dispersed pigments, and are colored in their applied state. Inorganic topcoats consist of water-dispersed silicate compounds and are transparent in their applied state. Topcoats contain integral lubricants and are applied in conjunction with Zinc Flake basecoats to form a coating system with enhanced performance attributes such as increased corrosion resistance, total coefficient of friction properties, chemical resistance, and color. These zinc-flake basecoats and topcoats are applied by conventional dip-spin, dip-drain, or spray methods to fasteners which can be handled through a cleaning, coating, and curing operation. The maximum curing temperature is 482°F [250°C].
The coating systems are classified into four (4) grades according to the requirements provided . The process application parameters and cure temperatures shall be in accordance to the recommendations of the coating system manufacturer.
| Grade |
Coating System |
Color Code |
Finished Appearance |
Friction Code |
Average Total Coefficient of Friction (μtot)A |
| Basecoat |
Topcoat |
| ASTM F3019/3019M Grade 1 |
Zinc-Flake |
None |
... |
Silver / Grey |
... |
... |
| ASTM F3019/3019M Grade 2 |
Zinc-Flake w/Integral Lubricant |
None |
... |
Silver / Grey |
... |
0.14±0.03 |
| ASTM F3019/3019M Grade 3 |
Zinc-Flake |
Organic |
B |
Black |
L2 |
0.14±0.03 |
| L3 |
0.17±0.03 |
| D |
Dark Blue |
... |
0.17±0.03 |
| G |
Green |
... |
0.17±0.03 |
| K |
Light Blue |
... |
0.17±0.03 |
| R |
Red |
... |
0.17±0.03 |
| S |
Silver |
L2 |
0.14±0.03 |
| L3 |
0.17±0.03 |
| Y |
Yellow |
... |
0.17±0.03 |
| ASTM F3019/3019M Grade 4 |
Zinc-Flake |
Inorganic |
... |
Silver / Grey |
L1 |
0.11±0.02 |
| L2 |
0.14±0.03 |
| L3 |
0.17±0.03 |
- (A) The average result of the Total Coefficient of Friction (μtot) as determined in accordance to ISO 16047 shall lie within these limits when tested per 6.5.1 Program A. Friction values are applicable to a minimum sample set of ten tested fasteners.
|
- ASTM F3019/3019M Grade 1 - requires application of the zinc-flake basecoat only. No topcoat is applied in Grade 1. Appearance of the coating in the applied state is silver/grey.
- ASTM F3019/3019M Grade 2 - requires application of the zinc-flake basecoat containing integral lubricant for friction modification. No topcoat is applied in Grade 2. Appearance of the coating in the applied state is silver/grey.
- ASTM F3019/3019M Grade 3 - requires application of the zinc-flake basecoat and organic topcoat. The organic topcoat contains integral lubricant for friction modification. Options for coating color and average total coefficient
of friction (μtot) are provided in above.
- ASTM F3019/3019M Grade 4 - requires application of the zinc-flake basecoat and inorganic topcoat. The inorganic topcoat contains integral lubricant for friction modification. Appearance of the coating in the applied state is silver/grey.
Options for average total coefficient of friction (μtot) are provided in above Table.
- Regardless of the process or materials used, the zinc-flake basecoat and organic/inorganic topcoats shall conform to all of the applicable requirements of ASTM F3019/3019M specification.
- Appearance
-
When viewed without magnification, the coating shall have a uniform appearance and be free from uncoated areas and discontinuities which affect part function such as excess coating.
- Adhesion
-
The coating shall show only trace peeling or removal along incisions or at their intersection, acceptance criteria 4A per Test Method D3359, following the X-Cut tape adhesion test.
NOTE : Due to the nature of the coating, some removal upon testing
is expected, but removal of the coating to expose the substrate is an indicator of poor coating adhesion.
- Corrosion Resistance
-
Corrosion resistance is related to the applied coating thickness of these coating systems. The coating system shall withstand neutral salt spray testing for the minimum time specified in below Table. Unless otherwise defined, acceptable corrosion
resistance shall be considered to be met where there is no red corrosion of the base metal on significant surfaces.
- Neutral Salt Spray Test Requirements
| Test Duration to First Appearance of Red Corrosion |
Minimum Average Coating Thickness of the Applied Coating SystemA |
| Hours |
Inch |
[Metric] |
| 240 |
0.157 mils |
[4 μm] |
| 480 |
0.197 mils |
[5 μm] |
| 600 |
0.236 mils |
[6 μm] |
| 720 |
0.315 mils |
[8 μm] |
| 960 |
0.394 mils |
[10 μm] |
- (A) The coating thickness is applicable to the complete coating system, basecoat and topcoat.
- NOTE 4: Bulk handling, transportation, and automatic sorting processes may lead to a reduction in the corrosion protection of the coating system. Depending upon the fastener, it may be necessary to reduce the corrosion test duration or increase
the minimum applied coating thickness.
|
- Blisters
-
There shall be no visible presence of blisters after testing in accordance.
- Thread Fit
-
The coating shall not have an adverse effect on normal installation and removal practices, as determined by the appropriate basic size "GO" thread gage or fit and function inspection method. For external threaded fasteners after coating, the torque
applied to the "GO" screw ring gauge shall not exceed 145d3 inch-pounds for inch series or 0.001d3 Nm for metric series, where d is the nominal thread diameter.
The maximum thickness of the coating which may be applied to threads on threaded
fasteners is limited by the basic thread size: for external threaded fasteners, 3A tolerance for inch or tolerance h (6h or 4h) for metric series, and for internal threaded fasteners, 2B tolerance for inch or tolerance H (6H, 5H, or 4H) for metric
series. Prior to the application of the coating system, external threads may be produced undersized and internal threads may be produced oversized to accommodate the coating thickness, provided the finished fastener after coating meets all specified
mechanical requirements.
For external threaded fasteners which are not permitted to be produced undersized due to specified requirements, the maximum thickness of the coating which may be applied is limited by the basic thread size: 3A tolerance
for inch and 6h tolerance for metric series. In these cases, the maximum coating thickness which may be applied shall be established prior to coating in consultation with the applicator.
For internal threaded fasteners which are not permitted
to be produced oversized due to specified requirements, the maximum thickness of the coating which may be applied is limited by the basic thread size: 2B tolerance for inch and 6H tolerance for metric series. In these cases, the maximum coating
thickness which may be applied shall be established prior to coating in consultation with the applicator.
-
Hydrogen Embrittlement
-
When specified in the purchase order, the applicator shall certify that the process does not expose the parts to acid.
NOTE : Non-electrolytically applied zinc-flake coating systems do not generate hydrogen during the coating process. Pre-treatment
processes which incorporate the use of acid cleaners (that is, acid pickling) may cause hydrogen adsorption.
-
Total Coefficient of Friction
-
Coating systems containing integral lubricant shall be demonstrated to meet the applicable average total coefficient of friction requirement specified in the purchase order.
- Adhesion
-
Adhesion of the coating shall be tested in accordance with Test Method D3359 X-Cut Tape Test and visually rated to classify the adhesion result.
- Corrosion
-
Corrosion resistance shall be tested in accordance with Practice B117 followed by Test Method D610 to rate the percentage of corrosion.
- Coating Thickness
-
Coating thickness shall be tested in accordance with Test Method B499, magnetic induction (See Note 6); Practice E376, eddy current; or Test Method B568, X-ray spectrometry. For referee purposes, microscopic examination in accordance with Test Method
B487 shall be used.
NOTE : Coating thickness test results determined by magnetic induction may be influenced if the parts have undergone magnetic particle inspections.
- Hydrogen Embrittlement
-
When specified in the purchase order, testing shall be conducted in accordance with Test Methods F606, F606M, or F1940. In the event that hardness reductions occur in test specimens due to coating curing times and temperature, testing shall be conducted
alternatively in accordance with F1624.
- Total Coefficient of Friction
-
The test shall be performed in accordance to ISO 16047 as specified in the purchase order. The results of testing shall be kept on file and submitted to the purchaser when required. NOTE : If unspecified in the purchase order, the default
test materials are zinc electroplated washers and zinc electroplated nuts or bolts in accordance to ISO 16047 .
- Test Program A
-
When permissible, testing shall be performed using M10 × 1.5 surrogate test bolts processed with the production parts. With this test program, it is recommended that friction testing be performed at a frequency which demonstrates statistical control
of the applicator's coating process.
- Test Program B
-
The use of surrogate bolts is not permitted in this test program. Samples for friction testing are selected from the production lots which have been coated. NOTE : Test hardware and fixturing specific to the part and capable instrumentation will
be required to conduct testing per Program B. These required materials may not be readily available at all test facilities or coating applicators. When necessary, a facility with the capability to perform the test may be designated.