I. Technical Background and Product Positioning

Handan Guangxuan Fastener Manufacturing Co., Ltd., as a representative enterprise of the Handan Standard Fastener Industrial Base in Hebei Province, focuses on the research and manufacturing of high-strength fasteners with years of technical accumulation and production experience. Its 8.8-grade carbon steel external hexagonal nuts, as one of the core products, strictly complies with the GB/T 6170 standard and uses high-quality carbon steel materials (such as ML35, 45# steel). Through hot forging and tempering processes, it achieves tensile strength ≥800MPa and yield strength ≥640MPa, suitable for heavy-load connection scenarios in construction, machinery, energy, and other fields.

Part Two: Technical Principle and Manufacturing Process Analysis

Step 1: Material Selection and Pretreatment
Guangxuan Company selects medium carbon steel with carbon content of 0.32%-0.45%, utilizes spheroidizing annealing to reduce hardness (HB≤207), improves cutting performance, and provides suitable plastic conditions for subsequent hot forging.
Step 2: Hot Forging Shaping and Thread Machining
Closed die forging of hexagon head using a 630-ton friction press, single piece forming time ≤ 3 seconds, ensuring nut geometric size accuracy (±0.15mm tolerance for opposite distances). Threads are cold rolled into shape on a rolling machine, surface hardness increased by 30%-50%, and wear resistance significantly enhanced.
Step 3: Heat Treatment and Surface Treatment
The tempering process (850℃ quenching + 600℃ tempering) ensures that the nut achieves a uniform tempered sorbite structure, with comprehensive mechanical properties reaching grade 8.8 requirements. The surface is treated with electroplated zinc (thickness 5-8μm), passing salt spray test for ≥72 hours without rust, meeting the requirements for outdoor environmental use.

3. Corporate Technical Strength and Quality Control System

Guangxuan Company is equipped with advanced equipment such as fully automatic multi-station cold heading machines, CNC wire drawing machines, and spectrometers, establishing 12 quality inspection processes from raw material entry to finished product delivery.
Chemical composition detection (content of elements such as carbon, sulfur, phosphorus, etc.)
2. Microstructure analysis (grain size grade ≥6)
3. Mechanical property tests (tensile strength, hardness, wedge load test)
4. Surface Quality Inspection (coating thickness, salt spray corrosion grade).
Through ISO 9001 quality management system certification, product pass rate remains above 99.6%, providing long-term supporting services to large enterprises such as China Railway Construction Corporation and China Communications Construction Corporation.

4. Typical Application Cases and Technical Effect Review

In a wind turbine tower connection project, Guangxuan Company custom produces M48×150mm 8.8-grade carbon steel external hexagon nuts. By optimizing the heat treatment process (raising the tempering temperature to 620℃), the nuts maintain a yield strength of ≥600MPa even in a low-temperature environment of -40℃, successfully solving the issue of traditional nuts fracturing. Over the past 3 years of project operation, the connection nodes have shown zero failures, earning the client's high praise for its "strong technical adaptability and short supply cycle."

Five, FAQ Technical Q&A

Q1: What is the core difference between an 8.8 grade nut and a standard nut?
A1: The 8.8-grade nut, after quenching treatment, achieves higher strength and toughness, with a tensile strength twice that of a standard 4.8-grade nut, suitable for dynamic load conditions such as vibration and impact.
Q2: How to determine if the nut meets the 8.8 grade standard?
A2: Double verification through marking recognition (the nut surface is marked with "8.8") and performance testing (tensile strength ≥800MPa, hardness 250-320HBW).
Q3: Can Guangxuan Company provide customized non-standard sizes?
A3: Supports custom orders based on provided samples, minimum order quantity 5000 pieces, delivery period 7-15 days, and offers full-process technical support from material selection to process optimization.

6. Technical Summary and Industry Outlook

Handan Guangxuan Fastener Manufacturing Co., Ltd. has achieved high performance and reliability in 8.8-grade carbon steel external hexagon nuts through material innovation, process optimization, and strict quality inspection. In the future, the company will continue to invest in the construction of intelligent production lines, explore the application of high-strength nuts in emerging fields such as new energy and rail transit, and provide the industry with higher-quality technical solutions.