High Tensile Carbon Steel Hex Head Bolts Zinc Black Finish

High Tensile Carbon Steel Hex Head Bolts Zinc Black Finish are core industrial fasteners made of medium carbon steel via quenching and tempering heat treatment. The product covers strength grades 4.8, 8.8, 10.9 and 12.9, two mainstream surface treatments: zinc plating and black oxide coating, meeting general mechanical assembly and heavy load connection demands. Ningbo Gangtong Zheli Fasteners Co., Ltd has specialized in manufacturing such hex fasteners for over 12 years, with stable raw material supply from domestic qualified steel mills. We strictly select SAE1045 medium carbon steel raw coils, conduct incoming material hardness inspection before putting into production to eliminate unqualified raw materials fundamentally, and ensure consistent mechanical performance of finished bolts in mass production.

Production & Technical Advantages

All machining procedures of High Tensile Carbon Steel Hex Head Bolts Zinc Black Finish are finished on automated cold heading and thread rolling equipment. The thread precision reaches 6g tolerance standard, tensile strength strictly follows international mechanical property standards, and anti-rust coating thickness is controlled at 6-12μm to resist mild atmospheric corrosion. The factory owns 32 sets of full-automatic production lines, daily output of hex bolts reaches 18 tons, and standardized quality inspection stations are arranged in every production link. Each processing station is equipped with special measuring tools for real-time size sampling, and defective semi-finished products will be screened out immediately to avoid flowing into the next processing procedure.

Application & Matching Scenarios

High Tensile Carbon Steel Hex Head Bolts Zinc Black Finish are widely adopted in engineering machinery, automobile chassis, steel structure frame, agricultural equipment and power support installation. The product supports full-thread and half-thread customization, metric standard sizes range from M6 to M48, and all common specifications maintain permanent stock for global bulk purchasers. The surface treatment can be adjusted according to clients’ local storage and service environment. For coastal humid areas, we can thicken zinc coating to extend anti-rust service life, while black oxide finish is more suitable for indoor dry mechanical assembly with low cost.

Quality & Global Service Support

Every batch of finished High Tensile Carbon Steel Hex Head Bolts Zinc Black Finish passes tensile test, hardness test and salt spray test before delivery; salt spray test duration for zinc coated versions can reach 48 hours, black oxide versions reach 24 hours. Ningbo Gangtong Zheli Fasteners Co., Ltd provides third-party test reports upon clients’ request, and has established long-term stable cooperation with industrial buyers from Europe, Southeast Asia and North America, offering customized size and surface treatment solutions for different regional market standards. Our professional technical team replies to all parameter and customization inquiries within working hours, and sorts out matching product suggestions according to clients’ actual installation load conditions.