Threaded Rod Eye Bolt

The China Xiaoguo® Threaded Rod Eye bolt is made of 42CrMo material with modified heat treatment, and its fatigue life can reach 2 million cycles. Before placing an order, free samples can be provided, along with a third-party fatigue test report and related inspection reports.

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Product Description

Surface Treatment Introduction

The following is an introduction and comparison of the main surface treatment processes for Threaded Rod Eye bolt.

（1）Electro-galvanizing

Electro-galvanizing is a process that deposits a layer of zinc on the surface of Threaded Rod Eye bolt through electrolysis, and it is the most common and economical method of corrosion prevention.

Color: Exhibits a blue-white, multicolored or black lustrous appearance.

Salt spray test: Does not develop red rust after being maintained for 48 to 72 hours.

Advantages: Low cost, bright appearance and can meet general indoor rust prevention requirements.

Disadvantages: Limited corrosion resistance, not suitable for outdoor or high-humidity environments.

（2）Hot-dip galvanizing

Hot-dip galvanizing involves immersing the bolts in molten zinc at approximately 450°C, resulting in a thicker layer of zinc-iron alloy.

Color: Silver-gray

Salt spray test: Can last for over 500 to 1000 hours

Advantages: Excellent corrosion resistance, thick and durable coating

Disadvantage: Rough appearance

Threaded Rod Eye Bolt

（3）Dacromet

Dacromet is a coating process that attaches zinc and aluminum sheet-like powders to the surface of Threaded Rod Eye bolt through sintering.

Color: Matte silver-gray

Salt spray test: Over 1000 hours.

Advantages: Excellent corrosion resistance, no hydrogen embrittlement, stable torque

Disadvantages: Contains hexavalent chromium (subject to environmental restrictions); high price

（4）Mechanical galvanizing

Mechanical galvanizing is a process that involves "cold welding" zinc powder onto the surface of bolts through mechanical impact. The entire process does not require heating or acid washing.

Color: Silver Grey

Salt spray test: 1000 hours +

Advantages: No hydrogen embrittlement, uniform coating (50-85 µm)

Disadvantages: High cost, difficult to process small specifications

（5）Black Oxide

A magnetic tricobalt ferrite film with a thickness of 0.5 to 2 micrometers is formed on the surface of the bolt through chemical oxidation, without significantly altering the size.

Color: Black

Salt spray test: 3 - 5 hours

Advantages: Lowest cost, no impact on size

Disadvantages: Extremely weak corrosion resistance, must be coated with oil

How to choose the surface treatment?

How to choose the surface treatment? Please specify the usage environment, strength grade and budget of the Threaded Rod Eye bolt. Here are the common options. If you need any assistance, we will communicate with you and provide precise advice.

（1）Indoor dry environment, below grade 8.8 → Electro-galvanizing.

（2）Outdoor environments with moisture or salt spray → Hot-dip galvanizing (for carbon steel) or 304 stainless steel.

（3）High strength (≥ 10.9 grade) and requiring strict anti-corrosion → Dacromet or mechanical galvanization.

（4）Highly corrosive environment (marine/chemical) → 316 stainless steel in its natural color.

Just need temporary rust prevention or a black finish → Stain removal + Rust inhibitor.

Threaded Rod Eye Bolt

Mon	M8	M10	M12	M16	M20	M24	M27	M30	M33	M36	M39
P	1.25	1.5	1.75	2	2.5	3	3	3.5	3.5	4	4
d1 max	8.036	10.036	12.043	16.043	18.043	22.052	25.052	28.052	30.052	32.062	35.062
d1 min	8	10	12	16	18	22	25	28	30	32	35
dk max	18	20	25	32	40	45	50	55	60	65	70
dk min	16.9	18.7	23.7	30.4	38.4	43.4	48.4	53.1	58.1	63.1	68.1
s max	11	14	17	19	24	28	30	34	38	41	46
s min	10.3	13.3	16.3	18.16	23.16	27.16	29.16	33	37	40	45
ds max	8	10	12	16	20	24	27	30	33	36	39