Five advanced heat treatment technologies

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The advancement of technological levels has led to continuous improvements in metal heat treatment techniques. Traditional heat treatment methods cause certain environmental pollution and pose threats to human health. Modern technology has been used to improve these heat treatment techniques, and we will now share with you the most advanced ones available today for use. 1. Controlled Atmosphere Heat Treatment: Controlled atmosphere heat treatment is primarily used to prevent oxidation and decarburization, while also enabling precise control over carburizing and nitriding processes. It was first applied in industrial production at the end of the 1980s, and today it is used on a very wide scale. Equipment manufacturers from home and abroad, taking into account the characteristics of the Chinese market, have introduced a range of controlled-atmosphere heat treatment furnaces with various grades and functions. Large-scale models such as Epson’s sealed box-type multi-purpose furnaces, as well as Fengdong’s fully automated and intelligent sealed box-type multi-purpose furnace production lines, can not only handle processes like carburizing and carbonitriding, but also enable various heat treatment techniques such as bright quenching and bright annealing. It can handle a range of tasks including computer-aided design, production management, logistics management, on-site control, quality management, and process management. At the same time, it has transformed the previously “dirty, messy, and poorly organized” environment of heat treatment workshops into one that is neat and tidy. Of course, these production lines are quite expensive and are suitable for mass production, such as in the automotive industry. Domestic manufacturers, in particular, closely follow user requirements and have introduced a variety of controllably atmospheric furnaces that are reasonably priced, come in diverse styles, and offer superior performance. It is generally capable of optimizing process parameters, predicting and precisely controlling the distribution of carbon concentration, thereby achieving an ideal concentration profile and case structure. It supports computer-based management, features a simple menu design, and offers a user-friendly interface. II. Vacuum Heat Treatment Vacuum heat treatment is a new type of heat treatment technique that combines vacuum technology with heat treatment techniques. The vacuum environment in which vacuum heat treatment takes place refers to an atmosphere with a pressure lower than one atmosphere, including low vacuum, medium vacuum, high vacuum, and ultra-high vacuum. In fact, vacuum heat treatment also falls under the category of atmosphere-controlled heat treatment. The application and development of vacuum heat treatment technology have been further improved and promoted. It features no oxidation or decarburization, a clean and bright surface of the workpiece after quenching, high wear resistance, no pollution, and a high degree of automation. Heat treatment techniques such as vacuum annealing, vacuum degassing, vacuum oil quenching, vacuum water quenching, vacuum hardening, vacuum tempering, and vacuum carburizing are widely used in industrial production. In recent years, with the advent of high-pressure gas quenching vacuum furnaces, the vacuum quenching of high-speed steel tools has become a reality. There are many manufacturers of vacuum furnaces, including domestic or joint-venture companies such as Epson, the French company ECM Industrielle Fours, and G-M Company, among others. There are also many well-known brands from domestic manufacturers, such as the \"Great Wall\" series produced by the China Aerospace Science and Industry Corporation, and the WZ series of vacuum furnaces developed by the Beijing Institute of Mechanical and Electrical Engineering. These products offer significant competitive advantages in terms of technology, performance, and price in the domestic market. Vacuum heat treatment is set to become one of the most widely used and important technologies in heat treatment workshops. III. Induction heat treatment and ion nitriding heat treatment technologies. Induction heat treatment is widely used in industries such as the automotive industry, construction machinery, and petrochemicals, thanks to its advantages of high efficiency, energy conservation, cleanliness, and flexibility. Nearly 40% of auto parts can be subjected to induction heat treatment, such as crankshafts, gears, universal joints, half-shafts, etc. By using induction heating, the processing of many products can be carried out on fully automatic or semi-automatic production lines, which improves the stability of product quality, reduces labor intensity, and enhances the working environment. The fastest-growing sector in China is induction heating power supplies; the old-style electronic oscillation tubes have fulfilled their historical role, and they have been replaced by all-transistor designs. A microcomputer controls the transistor-regulated power supply; this ensures stable and convenient regulation with high precision, while **reducing** interference from grid harmonics. The solid-state high-frequency heating devices that have been developed in recent years offer obvious advantages; they no longer rely on expensive, fragile, and energy-intensive electron tubes, as well as the accompanying anode step-up transformers, anode water jackets, filament voltage regulators, etc. Instead, they use MOSFET power electronic devices, which allow for a one-third reduction in energy consumption and a one-half reduction in water usage. And quenching machines equipped with heating power sources have also made great progress. This is reflected in: ① a significant increase in manufacturers of machine tools, as previously only Tianjin No. 9 Machine Tool Factory was active in this field. ②The precision, stability, and degree of automation of quenching machines have been greatly improved. ③The technical capabilities of specialized quenching machine tools have been fully utilized. Ion nitriding technology is characterized by a clean surface of the parts after treatment, as well as good corrosion resistance, minimal deformation, and high wear resistance. Compared to gas nitriding, it has advantages such as a shorter cycle time, higher efficiency, and less pollution. In recent years, ion nitriding has developed rapidly, especially with the advent of pulse power supplies for ion nitriding furnaces, which separate the physical parameters of the discharge (voltage, current, gas pressure) from the temperature control parameter (pulse width). It enhances the adjustability of the process, facilitating the selection and precise control of process parameters. IV. Quenching media and cooling techniques. An ideal quenching medium should possess the following characteristics: ① Mass-type: rapid cooling at high temperatures and slow cooling at low temperatures. That is, to eliminate cracks and reduce quenching deformation. ②Environmentally friendly: No emission of toxic or harmful dusts or gases; it is difficult to ignite. The workpieces can be easily cleaned after quenching, it does not cause corrosion to equipment, and it does not irritate or burn the skin. ③Stable type: The properties of the workpiece remain uniform and stable after quenching, and the properties of the medium itself remain stable over a certain period of time. ④Economy version: high quality at a good price, low energy consumption. In recent years, quenching media have developed very rapidly. The performance of quenching oils has improved, and research and application of organic polymer quenching media have seen unprecedented development. Abroad, there are the American companies Goodfulton and Derunbao, as well as the British company PB Petroleum. In China, there are companies such as Beijing Huali Fine Chemicals Company and Nanjing Kerun Fine Chemicals Company. V. Adoption of new surface strengthening technologies and promotion of heat treatment in nitrogen-based atmospheres. The existing methods for treating tool surfaces are limited to outdated techniques such as steam treatment and nitridation, which generally only manage to increase the tool’s lifespan by 30% to 50%. Since the 1980s, our country has independently developed as well as introduced from abroad the QPQ salt bath composite treatment technology and the PVD titanium oxide physical coating technology. The former can steadily increase tool life by 2 to 3 times; it features simple equipment and low costs, making it particularly suitable for ordinary cutting tools. The latter can increase tool life by 3 to 5 times, and is suitable for various precision and expensive gear cutting tools. A nitrogen-based atmosphere is used for heat treatment and chemical heat treatment; it enables oxidation-free decarburization during heat treatment and helps to prevent nitrogen embrittlement. Chemical heat treatment in a nitrogen-based atmosphere reduces defects such as internal oxidation, thereby improving the quality of the chemical heat treatment.