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The main failure mode is fatigue strength bolts

At this stage, China's manufacturing industry with the fastener with the world advanced level there are still a wide gap between the next 10 years to upgrade our manufacturing and fasteners, to the critical period from great manufacturing power.

currentFastener marketCompared to the level of foreign demand and still not a small gap, in particular in: the high-end variety, low level, the quality of instability, early failure rate, poor reliability. Drawings and material composition can provide China with the introduction of technology, but the heat treatment technology is strictly confidential, on the one hand the lack of national standards support, on the other hand the design specifications by foreign standards are almost harsh.

Our national economy is entering a new stage of development, infrastructure construction will be advanced stages of development (high-rise building, high-performance large-scale steel construction, high-speed transportation network, efficient transportation network, Efficient long-distance pipelines, large ports and transportation hubs, etc.), and to a large aircraft, large-scale power generation equipment, automobiles, high-speed trains, large ships, large equipment as the representative of advanced manufacturing will also enter important development direction. Thus, the fastener will enter an important stage of development. Development of developed countries shows that full access to advanced manufacturing-based stage of development, the use of high-strength fasteners will grow rapidly. Fastener enterprises To improve the technological level, the device must be from improved technology to improve start, host of domestic enterprises will not detour to imports, which is a favorable trend fastener enterprises in the current situation.

China fastener enterprises now have no new benefits, restrictingfastenerPower bottlenecks. Than most fastener business characteristics of our countryCold Heading, Cold extrusion, cold-emphasis on technology, engineers Proficient in mold design, often heavy cold, light heat treatment, some companies rely on outsourcing heat treatment to ensure the shipment. Fasteners can not guarantee the quality, over time, relying on the processing, it is a direct impact of innovation and hair fasteners exhibition.

However,Heat TreatmentThe importance of our country and some companies can not get the attention it deserves in terms of the relevant research programs, development planning, project guidelines and discipline settings or missing content of heat treatment, This situation needs to be reversed. Moment, at different levels to take measures to promote research fastener heat treatment technology for the realization of China's manufacturing power by the fastener, the fastener manufacturing power transformation of great significance.

Fastener coupling play, positioning and sealing in mechanical components, where the largest amount of bolts. There are five personality can rank high strength bolts, namely 8.8, 9.8, 10.9,12..9 and 12..9 level. According to the technical requirements, which have five grades bolts heat treatment. Heat treatment is to improve the mechanical properties of bolts, tensile strength and yield products to meet the provisions of Stronger than; selection of materials is to ensure the quality of foundation. Heat treatment technology, especially its intrinsic quality is essential for high-strength bolts.

Heat treatment is to control the performance of fasteners, to ensure safe, reliable and long-life key technologies, advanced materials is a core element of high-end machinery and equipment competitiveness. The bolt of steel carbon content of 0.20% to 0.55% of the low, medium carbon steel, low alloy steel. Properties of the material is not simply dependent on its composition, can greatly improve the performance of the material by heat treatment, the full potential of the material.

Well heat treatment, a few parts. So far, the heat treatment has been specializing in the field of heat treatment was promulgated 83 national and industry standards, there are more than 10 criteria to be submitted for approval. Development of China's fastener industry, it is necessary not only shows the importance of heat treatment on the fasteners, but also reflects the development of the fastener can not be separated heat treatment.

According to statistics, in the case of failure of the fastener, material and heat treatment of the reasons account for more than 80%. While businesses can press GB / T3098.1-2010 standards of production, but the yield Ratio, surface removal, carbon, microstructure, impact toughness is often omitted in the detection of targets, due to the presence of significant quality problems, resulting in alternating stress load of plastic deformation or fatigue fracture, but such projects And heat treatment processes are closely related, that the anti-brittle fracture fastener technology and heat treatment are inseparable.

Impact toughness fasteners plastic deformation and fracture energy absorption capacity of the whole process, is the overall performance of strength and ductility in the domestic fastener or important research topic, toughness and heat treatment technology abroad It is considered confidential and will not leak. Therefore, fasteners-brittle fracture technology is wisdom, is the core competitiveness of enterprises, who owns anti-brittle fracture technology, will be able to upgrade its products, brand name, have carve automobile standard parts market Advantages, to create wealth for their own businesses. Therefore, anti-brittle fracture fastener heat treatment technology is a new technology, is the cornerstone of the fastener industrial transformation and upgrading.

High strength boltsThe main failure mode is fatigue, it features a sudden failure in the absence of significant deformations. The key to solving the problem of fatigue failure is heat treatment technology. Heat-treated material not only gives limited performance and service performance limits given strength bolts, high strength bolts for the service provided a guarantee. Thus, fastener heat treatment is very important.

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