JIS H8615

JIS H8615 stipulates electrochrome plating of effective surfaces performed on iron, steel and non-ferrous metal substrates for industrial purposes such as wear resistance.

1. 1. Definition

The definitions of the main terms used in this standard are based on JIS H0400 and the following.

a) Effective surface The surface of a part that is or should be coated and whose coating is of primary performance and appearance.

b) Porous chrome plating Grooves or holes are formed on the surface of the plating. There are the following two things.

1. Etching type, which is made porous by electrolytically etching after plating. There are channel, pinpoint and intermediate types.

2. Knurling type A base material that is mechanically processed into a porous surface and reflected on the plated surface.

c) Porousness Percentage of the area occupied by grooves or holes within an arbitrary area on the porous chrome plated surface. (Reference: Chrome plating other than ordinary chrome plating may be specified for special applications.)

1. Chrome plating without cracks

It is a chrome plating that is a little soft but not brittle and basically has no cracks. Therefore, it exhibits better corrosion resistance than ordinary chrome plating. This plating is generally not thicker than 25 μm, is not finished by grinding, and is not used on surfaces that are subject to high loads. When this chrome plating is heat-treated, the corrosion resistance is lowered.

2. Porous chrome plating

Chromium plating that is mechanically, chemically or electrochemically porous to improve oil retention. The degree of porosity, type (eg, channel or point) and method of measurement of acceptance criteria are specified.

3. Crack chrome plating

Microcrack chrome plating is a plating that creates a microcrack pattern in which there are 250 or more invisible cracks per cm in any direction on the entire effective surface. In addition, microcrack chrome plating has cracks of 250 or less per cm. The hardness of crack chrome plating is generally the same as that of ordinary chrome plating, and due to its structure, oil can be easily retained. Microcracks have higher corrosion resistance than microcrack chrome when the base is nickel-plated.

4. Double chrome plating

Usually, uncracked chrome plating is used as the base plating, and chrome plating is usually applied on top of it. Therefore, the hardness is usually the same as that of chrome, but the corrosion resistance is high.

2. Plating symbol

The plating symbol is based on JIS H 0404 and Table 1, in addition to the element symbol Cr for chrome plating followed by the symbol I for industrial use.

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Remarks 1. When two or more types of processing are performed before and after plating, each symbol is indicated by separating them with commas from left to right in the order of processing.

Remarks 2. The final surface roughness of plating is based on JIS B 0601.

3. 3. quality

1. Appearance of plating

The appearance of the plating shall be tested according to 8.2 and the surface shall be smooth and free of any harmful defects such as charring or humps. However, it does not necessarily have to be smooth for matte finishes (liquid honing, blast finish, porous processing, etc.).

2. Plating surface roughness

The surface roughness of the plating applies only to applications where this quality is of particular importance, the quality of which is subject to agreement between the parties to the delivery.

3. Minimum plating thickness and tolerance

The minimum thickness and tolerance of plating applies only to applications where this quality is of particular importance and is tested by thickness testing, the quality of which is subject to agreement between the parties to the delivery.

4. Plating porosity

The porosity of porous chrome plating is applied only to applications where this quality is of particular importance and is tested by porosity testing, the quality of which is subject to agreement between the parties to the delivery.

5. Plating adhesion

The adhesion of the plating shall be tested by an adhesion test and there shall be no peeling or swelling of the plating.

6. Plating hardness

The hardness of the plating is tested by a hardness test, and the Vickers hardness is 750 or more. However, depending on the application, the Vickers hardness may be determined by an agreement between the delivery parties.

7. Abrasion resistance of plating

The wear resistance of the plating applies only to applications where this quality is of particular importance and is tested by wear resistance tests, the quality of which is subject to agreement between the parties to the delivery.

8. Corrosion resistance of plating

The corrosion resistance of the plating is applied only to applications where this quality is particularly important, and the test is conducted by the corrosion resistance test, and the quality is based on the agreement between the delivery parties.

4. Base material

The condition of the substrate before plating has a significant effect on the quality of the plating. In particular, when the base material is supplied by the ordering party, the ordering party must show information about the base material in the processing specifications and the like.

(Remarks, the processor examines the effective surface of the item for visible defects, i.e., holes, cracks and coatings that are harmful or unfavorable to the final finish, if these defects are found. If so, pay attention to the ordering party before putting it in the plating process. Also, the processor is not responsible for the defective plating due to surface defects that cannot be observed with the naked eye.)

5. Treatment of base metal before and after plating

1. Shot peening process

If shot peening treatment is specified for the purpose of improving fatigue strength, the conditions are based on the agreement between the delivery parties. Unless otherwise specified, the peening strength is set by the method of Annex 1.

2. Base plating

When base plating is performed for the purpose of improving the corrosion resistance of plating, the type and film thickness of the plating shall be in accordance with the agreement between the delivery parties.

3. Stress relief before plating

If stress relief before plating is specified for steel bases, etc., the conditions are based on the agreement between the delivery parties.

Annex 3 shows the heat treatment conditions for stress relief before plating, which are described as references in the corresponding international standards.

4. Removal of hydrogen brittleness after plating

If hydrogen brittleness removal after plating is specified for steel products, etc., hydrogen brittleness removal is performed by heat treatment within at least 4 hours after plating. The heat treatment conditions are based on the agreement between the delivery parties.

Annex 4 shows the heat treatment conditions for removing hydrogen brittleness after plating, which are described as references in the corresponding international standards.

6. test

1. Preparation of test piece

Specimens are usually made from products. However, if the plated product itself cannot be used as a test piece, the test is performed using an alternative test piece.

As much as possible, the substitute test piece must be made of the same material as the plated part and under the same plating conditions.

2. Appearance test

Appearance tests are performed visually to check for surface smoothness, degree of adhesion, charring, pits, humps and markedly uneven plating. (Remarks: When investigating the state and number of cracks, use an optical microscope with a magnification of 100 times or more.)

Note 1. Since the smoothness of plating is governed by the quality of the base material finish, the following a and b must be noted.

The surface of the plated area should be smooth and free of cavities, cutlery scratches and other non-uniformities.

b. The surface of parts that are not finished after plating shall be finished after plating and at the same level as or better than the required finished surface before plating.

Note 2. If the adhesion of the plating is poor, the plating may be partially detached like scales. In addition, peeling may occur due to defects in the substrate.

Note 3. Generally, plating has a metallic luster, so charring is subject to testing. This does not apply to those used after plating and polishing.

3. Thickness test

As a general rule, the thickness test uses the microscopic cross-section test method specified in JIS H8501. However, depending on the rules between the parties concerned with delivery, a magnetic test method, an electrolytic test method, a stylus scanning test method, or the following method may be used.

A method using a micrometer or cylinder gauge, measuring the product dimensions with JIS B7502, JIS B7515 or a measuring instrument with an accuracy equal to or higher than these, and after plating is completed, measure the same point and the difference is the plating thickness. Let's say. However, the measurement should be performed at least 3 points.

Note 1. For base polishing, the dimensions after polishing shall be the standard, and if plating is on both sides, it shall be 1/2 of the measured value. For those that perform polishing finish after plating, the polishing margin must be taken into consideration when specifying the plating thickness.

4. Porousness test

In the porosity test, after porous chrome plating, the surface state of the plating or the surface state transferred to the celluloid plate is magnified 100 times by a microscope using a microscope to determine the area of ​​pores per unit area. According to Annex 2.

Note 1. Regarding the test When finishing after porous chrome plating, it is necessary to remove free foreign matter from the grooves or holes on the surface immediately after the finishing is completed. (Reference: After finishing, the surface may have uneven gloss due to diffused reflection of light.)

Note 2. A thin celluloid plate (thickness 0.1-0.3 mm) is coated with an aluminum acetate solution in which celluloid is dissolved, pressed against the surface of the object to be inspected, dried, peeled off, and transferred to the celluloid. A method of observing the surface under a microscope.

5. Adhesion test

The adhesion test shall be performed by any of the grindstone test method, bending test method or tensile test method specified in JIS H8504.

6. Hardness test

The hardness test is based on JIS Z2244 and the following.

In the hardness test, at least 5 points are measured, and the arithmetic mean value is taken as the plating hardness. As a general rule, the test load shall be 0.490 3N or more, and the load holding time shall be 15 seconds or more.

If the measurement is difficult, the test may be performed using a part of the test piece of the adhesion test.

a) As a general rule, the test surface of the test piece should be flat, and the surface should be carefully finished so that it will not be heated.

Further, in porous chrome plating, it is desirable to measure a flat portion. When the porosity is large and the area of ​​the flat portion is small, the perforated portion may be removed for measurement.

b) The thickness of the plating shall be at least 1.5 times the diagonal length of the resulting depression.

c) To display the hardness value, do as follows.

Example: When the test load is 0.490 3N, the holding time is 15 seconds, and the Vickers hardness is 800, the hardness symbol HV0.05 representing the test load 0.490 3N is used, and the test load is expressed as 800 HV0.05 / 15 or 800 HV0.05.

7. Abrasion resistance test

The anti-wear test is based on any of the sand drop wear test, injection wear test, reciprocating motion wear test, flat plate rotary wear test, and two-wheel drive wear test specified in JIS H8503.

However, other methods that have been validated by agreement between the parties to the delivery may also be used.

8. Corrosion resistance test

The corrosion resistance test is based on the neutral salt spray test method specified in JIS H8502.

7. Inspection

a) Plating is 6. Test by test, 3. Those that meet the quality regulations are accepted.

b) Specimens are removed from lots of the same parts according to JIS Z 9031.

Remarks 1. The selection of inspection items and test methods is based on the agreement between the delivery parties.

Remarks 2. The number of test pieces, inspection order, inspection target location, and alternative use of test pieces shall be in accordance with the agreement between the delivery parties.

8. How to call plating

The name of plating is based on JIS H 0404. However, when the base material is steel, the element symbol Fe can be omitted. The processing method before and after plating is referred to by inserting a diagonal line after the plating thickness using the symbols in Table 1, and the final surface roughness is the center line average roughness (Ra) specified in JIS B 0601 before and after plating. It is called by () of the processing method of.

9. display

Display the following items on the invoice or delivery note.

a) Plating symbol

b) Processing date

c) Processor name

d) Plating quality test results stated in the ordering party or processing specifications

10. Items to be stated in the purchase order or processing specifications

The ordering party may describe the following items in the purchase order and processing specifications, and omit the additional items by agreement between the delivery parties.

a) Basics

1. Plating symbol

2. Effective surface of plating (Present a physical sample as instructed or marked on the drawing)

3. Appearance (final surface roughness, gloss, etc.) (It is recommended to show a limit sample)

4. Inspection method

b) Appendix

1. Progress of heat treatment of the base material

2. If there is base plating, its type and thickness

3. Required plating quality and its test method

4. Acceptable plating surface defect type, size, extent and location

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