Martensitic Stainless Steel Fasteners Overcome Material Cracking Problem Achieve Import Substitution
author: www.qishine.com
2025-11-22
> On a fully automated production line at a factory in Zhoushan, a material that once gave the manufacturing industry a headache — martensitic stainless steel — is being cold-forged into precision hexagonal flange bolts for new energy vehicle production lines.
On a fully automated high-precision wire drawing-cold forging line at a factory in Zhoushan, modified martensitic stainless steel wire is being cold-forged into precision hexagonal flange bolts.
Previously, high-end fasteners that would crack during processing are now being independently produced in Zhoushan and have successfully replaced imports.
This technology breakthrough project, supported by the Zhoushan Science and Technology Bureau, has overcome the cold processing challenges of martensitic stainless steel fasteners, solving a "bottleneck" problem that has troubled the industry for years.
01 The "Bottleneck" Problem of "Industrial Joints"
Although high-end fasteners are small, they play a key role in equipment manufacturing and are known as "industrial joints."
Although high-end fasteners are small, they play a key role in equipment manufacturing and are known as "industrial joints."
From the battery packs of new energy vehicles to the core parts of engines, these fasteners that can withstand high pressure and high temperature are indispensable.
Due to its high strength, heat resistance, and corrosion resistance, martensitic stainless steel has become an ideal material for manufacturing fasteners for high-temperature critical components such as engine exhaust pipes and turbocharging systems.
However, the "hard and brittle" characteristics of martensistic stainless steel have always restricted its large-scale production.
"In the past, when using this material to make fasteners, they would often crack, making mass production impossible," recalled Engineer Jiang, the deputy director of the High-end Fastener Research Institute at a factory in Zhoushan.
The three major problems of insufficient material plasticity, surface micro-defects that become crack sources under pressure, and traditional lubrication techniques being unsuitable were like three big mountains blocking the path to the localization of martensitic stainless steel fasteners.
02 Technical Breakthrough
In the face of this common industry problem, the Zhoushan Science and Technology Bureau went deep into the front line to identify enterprise technology needs during the "Enter 100 Enterprises, Solve 100 Problems, Promote Integration" campaign.
In the face of this common industry problem, the Zhoushan Science and Technology Bureau went deep into the front line to identify enterprise technology needs during the "Enter 100 Enterprises, Solve 100 Problems, Promote Integration" campaign.
They quickly listed "Martensitic Stainless Steel Wire Drawing and Cold Forging Technology" as a major municipal industrial technology breakthrough project, with a total investment of over 7 million yuan in R&D funding.
The project team prescribed a series of "remedies" for the problems: developing a dedicated "annealing" process to make the material "soft" and tough before cold forging by precisely controlling the temperature.
Updating and iterating wire drawing technology, optimizing parameters such as sand belts and speed, to give the material a "fine polishing" and eliminate surface scratches and pits that cause cracking.
Developing a dedicated lubricating film technology to form a strong "protective film" on the material surface, greatly reducing friction during molding in the die.
With this "combination punch," the cold forging performance of the material has undergone a qualitative leap.
With the original technology, the fluctuation range of product tensile strength was as high as 44MPa, while the new technology stabilized it within 5MPa, achieving an extremely high level of performance consistency, with key indicators equal to or even better than similar foreign products.
03 From Laboratory to Production Line
After the technological breakthrough, Zhoushan established a comprehensive "technology R&D - achievement transformation" collaborative mechanism. For scientific research teams that have made major scientific and technological achievements, technology transfer service institutions provide services such as pilot testing and transformation.
After the technological breakthrough, Zhoushan established a comprehensive "technology R&D - achievement transformation" collaborative mechanism. For scientific research teams that have made major scientific and technological achievements, technology transfer service institutions provide services such as pilot testing and transformation.
After successfully breaking through the key technology, the Zhoushan Science and Technology Bureau immediately organized expert services in enterprises, helping the 7412 Factory build one fully automated high-precision wire drawing-cold forging production line.
Today, this production line has achieved an annual capacity of 3,000 tons of high-end stainless steel wire and 200 million precision cold-forged parts, driving the enterprise's annual new output value to 300 million yuan, with both capacity and output value doubling.
What is even more noteworthy is that the new process has achieved a major breakthrough of 100% material utilization, with no waste generated throughout the production process, and energy-saving and clean production is realized by eliminating the heating link.
04 Replacing Imports and Entering the Supply Chain of Well-known Car Companies
With the maturity of the technology and the formation of production capacity, these "Zhoushan-made" high-end fasteners have quickly entered the mainstream automotive supply chain.
They have been successfully applied in key parts such as automobile engines, battery pack fastening, and automobile seat transmission screw rods of well-known automobile companies such as Weichai and Yuchai.
"This means that we have successfully replaced imported products from international giants such as American ITW and German Würth," said the factory director.
"It has reduced procurement costs for downstream car companies by more than 25% and shortened the delivery cycle by more than 40%."
At present, the market share of this series of products in the domestic market has reached about 70%. The new products have also received orders from well-known car companies such as BYD and NIO.
This breakthrough not only reduced the cost per piece by 0.76 yuan compared with traditional hot forming, but also achieved an annual cost reduction of 3 million yuan, with the project's annual profit exceeding 5 million yuan.
05 Government Support for Industrial Upgrading
The successful breakthrough of this technology is inseparable from the precise support of government departments.
The successful breakthrough of this technology is inseparable from the precise support of government departments.
The Zhoushan Science and Technology Bureau has continued to carry out actions such as "Enter 100 Enterprises, Solve 100 Problems, Promote Integration," going deep into the front line to identify enterprise technology needs.
After learning about the common industry problems faced by the factory, it quickly organized expert demonstrations and provided R&D funding support.
In recent years, Zhoushan has fully leveraged the role of "technology deputy directors" and enterprise-based science and technology commissioners, establishing a city-county linkage mechanism to help enterprises promote their products.
It provides point-to-point promotion services for new technologies and products for related factories, driving more than 10 upstream and downstream enterprises such as Dinghai Haili Electric Appliance and Zhoushan Hongyi Surface Technology to achieve technology and product iteration upgrades.
Since the beginning of this year, the fastener industry in Zhoushan has added 47 million yuan in profits and taxes, effectively promoting the transformation and upgrading of the fastener industry in Zhoushan, basically achieving technology autonomy, product high-endization, and industry greening.
The breakthrough in the localization of martensitic stainless steel fasteners marks an important progress in China's high-end fastener field.
As "Zhoushan-made" high-end fasteners enter the production lines of well-known car companies such as Weichai, Yuchai, BYD, and NIO, the pace of China's manufacturing industry towards high-end, intelligent, and green transformation is accelerating.
Small screws reflect big transformation. The practice in Zhoushan has proven that through the deep integration of technological innovation and industrial innovation, China's manufacturing industry is climbing up in the global industrial chain.
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