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ISO 8677 Large Head Carriage Bolts Carbon Steel Class 8.8

QBH ISO 8677 large head carriage bolts are manufactured from carbon steel with property class 8.8. Featuring a large round head and square neck, they provide a secure fastening solution for applications requiring a smooth head profile and reliable tightening performance.

Customization Is Our Strength: With drawing-based manufacturing and flexible production options, we supply custom large head carriage bolts with tailored dimensions, thread configurations, and surface finishes (Plain, Zinc Plated, HDG), subject to order requirements. Contact us today to discuss your specific project needs.

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Product Details

Product Specifications

Place of Origin	CHINA
Standard	ISO 8677 Carriage Bolts Class 8.8
HS CODE	7318159001
Brand Name	QBH
Certification	ISO9001
Material	Carbon Steel
Thread Size	M5-M20
Production Process	Plain / Zinc Plated / HDG, Subject to order requirements
Grade	Grade C
Property Class	8.8
Delivery Time	Within 30Days

Product Introduction

Large Head and Square Neck Design

ISO 8677 large head carriage bolts, also known as cup head square neck bolts, feature a large rounded head and a square neck beneath the head. The square neck helps prevent the bolt from rotating during installation when fitted into a matching square hole or suitable material.

Carbon Steel, Property Class 8.8

These bolts are made from carbon steel and specified with mechanical property class 8.8. The 8.8 property class is specified separately from the ISO 8677 product grade C, which defines the product's dimensional and manufacturing characteristics. Mechanical properties are to be verified against the applicable requirements of ISO 898-1.

QBH Manufacturing & Customization

As a fastener manufacturer, QBH provides production support for large head carriage bolts in different dimensions and configurations. We focus on manufacturing consistency, quality control, and customized supply for international customers.

Material & Mechanical Properties

Material Characteristics

Carbon steel provides a balance of strength, toughness, and machinability, making it suitable for manufacturing high-strength fastening components. Material selection is based on the required mechanical properties, bolt dimensions, and applicable manufacturing specifications.

Mechanical Performance – Class 8.8

The bolts are specified to meet property class 8.8 requirements under ISO 898-1, subject to the applicable diameter range.

Mechanical Property	Requirement
Nominal Tensile Strength	800 MPa
Minimum Tensile Strength	800 MPa
Minimum Yield Strength / 0.2% Proof Stress	According to ISO 898-1 and applicable diameter range
Hardness	According to ISO 898-1
Property Class	8.8

Heat Treatment & Quality Inspection

Quenching and tempering are used to achieve the required strength and hardness for class 8.8 fasteners. Quality inspection may include dimensional checks, thread inspection, hardness testing, and mechanical property testing to ensure compliance with the specified requirements.

Dimensional Specifications & Thread

Item	Specification
Thread Diameter	M5–M20
Nominal Length	20–200 mm
Thread Type	Metric Coarse Thread
Thread Tolerance	6g, subject to applicable specifications
Product Grade	C
Head Style	Large Round / Cup Head
Neck Type	Square Neck

The dimensional scope of ISO 8677:1986 covers thread sizes from M5 to M20 and nominal lengths from 20 mm to 200 mm. Actual size combinations and production availability are subject to confirmation.

QBH also supports customized dimensions and specifications according to customer drawings and project requirements.

Applications

ISO 8677 large head carriage bolts are suitable for various fastening applications requiring a smooth rounded head and a square neck design.

Construction & Building: Used for fastening timber structures, brackets, and building components.
Furniture & Woodworking: Suitable for assembling wooden frames, furniture, benches, and other wood products.
Fencing & Railing: Used in fence panels, gates, posts, and railing system assemblies.
Agricultural Equipment: Applied in agricultural machinery, equipment frames, and trailer components.
Machinery & Industrial Assembly: Suitable for securing brackets, mounting plates, support structures, and general industrial components.

Product Specifications

Place of Origin	CHINA
Standard	ISO 8677 Carriage Bolts Class 8.8
HS CODE	7318159001
Brand Name	QBH
Certification	ISO9001
Material	Carbon Steel
Thread Size	M5-M20
Production Process	Plain / Zinc Plated / HDG, Subject to order requirements
Grade	Grade C
Property Class	8.8
Delivery Time	Within 30Days

Product Introduction

Large Head and Square Neck Design

Carbon Steel, Property Class 8.8

QBH Manufacturing & Customization

Material & Mechanical Properties

Material Characteristics

Mechanical Performance – Class 8.8

The bolts are specified to meet property class 8.8 requirements under ISO 898-1, subject to the applicable diameter range.

Mechanical Property	Requirement
Nominal Tensile Strength	800 MPa
Minimum Tensile Strength	800 MPa
Minimum Yield Strength / 0.2% Proof Stress	According to ISO 898-1 and applicable diameter range
Hardness	According to ISO 898-1
Property Class	8.8

Heat Treatment & Quality Inspection

Dimensional Specifications & Thread

Item	Specification
Thread Diameter	M5–M20
Nominal Length	20–200 mm
Thread Type	Metric Coarse Thread
Thread Tolerance	6g, subject to applicable specifications
Product Grade	C
Head Style	Large Round / Cup Head
Neck Type	Square Neck

The dimensional scope of ISO 8677:1986 covers thread sizes from M5 to M20 and nominal lengths from 20 mm to 200 mm. Actual size combinations and production availability are subject to confirmation.

QBH also supports customized dimensions and specifications according to customer drawings and project requirements.

Applications

ISO 8677 large head carriage bolts are suitable for various fastening applications requiring a smooth rounded head and a square neck design.

Construction & Building: Used for fastening timber structures, brackets, and building components.
Furniture & Woodworking: Suitable for assembling wooden frames, furniture, benches, and other wood products.
Fencing & Railing: Used in fence panels, gates, posts, and railing system assemblies.
Agricultural Equipment: Applied in agricultural machinery, equipment frames, and trailer components.
Machinery & Industrial Assembly: Suitable for securing brackets, mounting plates, support structures, and general industrial components.

FAQ

1. How do you let me trust you.

Jiaxing City Qunbang Hardware Co.,ltd hs its own right of import and export,QBH trademark in China,United States,European Union have been registered.At the same time,you can also check the registration information of our company in the China industry and Commerce system.

2. How about your price.

We will be based on different markets,for different quality and quantity,tailor-made prices for customers,in order to achieve win-win goal.

3. How do you control your quality.

Incoming quality contral( IQC)→Process Quality control(PQC)→Output quality control(OQC),and the random samples is sent to TUV for testing.If the customer received the goods and found quality problems,QBH company promises to be responsible for returning money or replenishing the goods

4. Could you provide free samples?

For new customer, We can provide free samples for standard fastener, But the clients will pay the express

charges. For old customer, We will send you free samples and pay express charges by ourself.

5. What is your packing.

Usually 25KG/carbon,36CTNS on the pallets,or 20-30kg/Bags,then on the pallet,QBH company personalized packagingis also available,like 10PCS/plastic bag or 10pcs/box,it can print some information

such as LOGO and pattern of customers.

6. What is your payment term

Normally,our terms of payment are TT and L/C,if we cooperate for a long time,we can reach the point of mutual trust,and fully support our customers to become bigger and stronger in the local market.Not only in the price concessions,but also in the payment can also be made on credit,Specific credit sales time needs to be negotiated separately.

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