Heat treatment technology has become a key technology for fastener manufacturing

Heat treatment is a key technology to control the performance of fasteners, ensure long life and safety and reliability, and is the core element of the competitiveness of advanced materials and high-end mechanical equipment.

Every international fastener manufacturer that produces famous brand products has always attached great importance to the research and development of heat treatment technology. Through a large amount of investment, long-term accumulation and continuous improvement, master unique heat treatment technology and strict confidentiality, others can create geometric elements Imitations with exactly the same accuracy, but their service life and reliability are hard to come by. The development of modern heat treatment technology has two major characteristics: one is the continuous in-depth formation of new heat treatment theories and processes based on the fundamental research of material structure transformation and its influence on performance; the second is to absorb the results of other disciplines (such as electromagnetic induction, laser, ion Beam, chemical thermodynamics and kinetics, combustion technology, heat transfer, etc.) developed new heat treatment technologies. my country has become a major manufacturing country. Although the scale of heat treatment has grown rapidly in the past 20 years, there is still a gap of decades between the technical heat treatment technology and the world's advanced level, which has caused the bottleneck phenomenon of domestic high-end fasteners lagging behind the mainframe.

In essence, the added value it brings to key components and equipment is much higher. For example, automobile fasteners are fasteners with high economic value. Due to the high requirements for quality and reliability, my country’s production cannot be fully localized; the engine connecting rod bolts, flywheel bolts, and flywheel bolts used in key parts of automobiles Wheel bolts, suspension bolts, etc. are all important fasteners related to life and property safety. At present, 40% to 60% rely on imports. Although their manufacturing technology has some similarities with general fasteners, their manufacturing and testing technology, equipment, materials, management control, etc. are very different, which is the highest and most concentrated embodiment of fastener technology. .

①To do a good job in the top few of heat-treated parts, the potential for energy saving and consumption reduction is huge;

②Improve the reliability of the product and protect the safety of people's lives and property;

③ Relying on advanced heat treatment technology to manufacture fasteners with small size, light weight, long life and high reliability, which greatly increases the added value of the whole machine;

④The research results in the field of heat treatment are catalysts for new materials, new products, and new equipment.

Application examples of heat treatment: such as 10.9 high-strength bolts, quenching and tempering treatment can greatly improve the tensile strength of the material, specify non-proportional extension stress, increase the yield ratio and impact toughness, so that the material has good strength and plastic toughness Cooperate. Due to the improvement of fatigue strength and impact toughness, a smaller material cross-section can be used in the design of high-strength bolts, thereby reducing the overall weight of the whole machine, saving space occupied by parts and energy consumption.

Commonly used low and medium carbon structural steel, low alloy structural steel, 20, 35, 45, 20MnTiB in GB/T699-1999 'Quality Carbon Structural Steel, 35CrMoA, 40Cr, 42CrMoA, 40CrNiMoA, 30CrMnSiA and other steels can give full play to the role of alloying elements only through quenching and tempering treatment. Not quenching and tempering is equivalent to wasting precious alloys.

GB/T3098.1-2010 'The mechanical properties of fasteners, bolts, screws and studs' new standard is released, emphasizing that the material requirements for products of grade 8.8 and above should have sufficient hardenability to ensure tightness The core of the thread section of the piece obtains about 90% martensite structure in the quenched state and before tempering. In fact, in order to ensure good hardenability for fasteners with a thread diameter of more than 20mm, the alloy steel material specified in the standard needs to be quenched and tempered. For this reason, metallographic inspection has developed rapidly in the fastener industry. Metallographic inspection not only uses metallographic microscope to study the internal structure of metal materials, but also conducts macroscopic inspection through the naked eye or under a low-power magnifying glass.

The main failure mode of high-strength bolts is fatigue, and its outstanding feature is sudden failure without significant deformation. The key to solving the problem of fatigue failure is heat treatment technology. Heat treatment not only endows the material with ultimate performance and the ultimate service performance of high-strength bolts, but also provides protection for the service of high-strength bolts. Therefore, the heat treatment of fasteners is very important. When some companies have product quality problems in heat treatment, it is not too late to think about the importance of heat treatment and the improvement of technology. Time does not wait for me, technological innovation is rare.