Standard Upgrade + Process Innovation: Comprehensive Industry Knowledge on Steel Fine-Thread Phosphating Screws

Steel fine-thread phosphating-treated screws, as a core category in the fastening industry, are widely used in key fields such as high-end manufacturing, new energy equipment, and the automotive industry due to their precise structure and stable protective performance. Recently, driven by stricter environmental policies, upgraded industry standards, and the upgrading of downstream demand, this category has achieved technological innovation and market expansion, becoming an important driver for the structural upgrading of the metal fastening industry. The following will summarize key industry knowledge based on the current industry situation, core technologies, and market trends.
The core advantage of fine-thread screws lies in their precision. They have a small pitch and a fine tooth profile, which, compared to coarse-thread screws, have stronger self-locking properties and less pre-tightening force attenuation. They can be adapted to vibration conditions, thin-walled connections, and precise adjustment scenarios, and are indispensable in fields such as new energy vehicle battery packs, servo equipment, and medical devices. Phosphating treatment, as the core surface protection process for them, forms a porous phosphate crystal film through chemical transformation on the steel substrate surface, providing functions such as rust prevention, friction reduction, locking, and coating base layer. It is a key link in ensuring the service life and assembly stability of the screws.
Recently, the phosphating process has shown a trend of green and efficient iteration. The traditional high-temperature phosphating, due to its high energy consumption and large amount of wastewater discharge, has been gradually replaced by the normal-temperature rapid phosphating process. Combined with counter-flow rinsing and recycling technology, the water resource utilization rate has increased to over 75%, significantly reducing the environmental protection treatment cost. At the same time, the breakthrough of the four-effect integrated phosphating technology has been achieved. It can complete degreasing, rust removal, phosphating and passivation simultaneously at normal temperature, significantly reducing the process time, and the chromium-free formula complies with the EU REACH certification requirements, meeting the needs of export enterprises. Currently, the mainstream phosphating processes are divided into zinc series and manganese series. The zinc series focuses on lubricity and is suitable for automated assembly; the manganese series has a dense and wear-resistant coating, mostly used in high-strength scenarios, and the phosphating film thickness is generally controlled at 2–8 μm. Combined with sealing treatment, the neutral salt spray performance can be improved to 72–120 hours.
Industry standards continue to be improved, promoting the upgrading of product quality. The new GB/T31.3-2025 standard, which came into effect on February 1, 2026, expands the range of fine-thread specifications, adds various urgently needed specifications, clarifies the technical requirements for 12.9 grade high-strength products and stainless steel series, and further specifies the criteria for surface defects. This addresses the issue of insufficient guidance in the previous version of the standard. At the same time, high-strength fine-thread screws commonly use alloy materials such as 35CrMo and 40Cr. After quenching and tempering treatment, their strength can reach 10.9 grade and 12.9 grade. Combined with low hydrogen embrittlement phosphating process, it effectively avoids hydrogen embrittlement risks and ensures the safety of critical connections.
The market demand is showing characteristics of high-end and customization. Domestic substitution is accelerating continuously. Driven by industries such as new energy vehicles, wind power, and photovoltaics, the demand for fine-thread phosphating screws has been continuously rising. By 2025, the proportion of fine-thread products in the total demand for fasteners is expected to exceed 40%. Leading enterprises are promoting full-process automated production, introducing AI visual inspection and digital traceability systems, and raising the product pass rate to 99.2%. However, small and medium-sized enterprises are facing dual pressures of environmental protection and quality control, and the industry concentration is gradually increasing. Currently, the domesticization rate of high-end fine-thread fasteners is close to 65%, gradually breaking the monopoly of overseas brands in the aerospace and high-end equipment fields.
In the future, the steel fine-thread phosphating treatment screw industry will develop along the directions of greening, intelligence and high-endization. Technologies such as nano-modified phosphating and functional gradient coatings will be further popularized to enhance the product's anti-corrosion and wear resistance. The deep integration of intelligent production lines and digital control will continuously shorten the delivery cycle and improve product consistency. Enterprises need to focus on the coordinated upgrading of materials, processes and quality control, and adapt to the high-end demands of downstream industries, in order to gain competitive advantages in the industry transformation.