Analysis: Application of steel in the manufacturing process of fasteners

Fastener steel needs to increase significantly

The price of iron ore remains high and the price of domestic steel is struggling to survive. This game war makes people worry about the future of fasteners. Fasteners, also known as industrial meters, are the most common general-purpose components with a large quantity and a wide range. They are closely related to the steel industry at all levels. Not only do they require a large number but are widely used.

In recent years, with the rapid growth of China's fastener industry, the demand for fastener steel has also increased. Iron and steel almost occupies 100% of the fastener products. At the same time, considering the 15%-20% of the material consumption in the production process, one ton of fasteners needs about 1.18-1.25 tons of steel, and fasteners must be worn every year. The amount of steel is considerable. According to relevant materials, in the cold heading steel market in 2003, the world's fastener demand reached 3 million tons, the demand increased to 4.5 million tons in 2005, and the world demand reached more than 5.5 million tons in 2006.

Steel is the most fundamental material in fasteners

Fasteners can be made of steel, non-ferrous metals, stainless steel, titanium alloys and other engineering materials. The processing methods can be hot processing and cutting, but more than 90% of them are processed by cold heading and refrigerant pressing. The products produced are of high precision, good quality, and high production compliance. China's fastener industry has maintained double-digit growth for five consecutive years.

Although the utilization ratio of non-ferrous metals and composite materials is increasing year by year, the influence of steel used in high-strength fasteners cannot be replaced.

All kinds of fasteners are usually made of cold-headed steel. In terms of category classification, in addition to normal carbon steel, the steel used for fasteners also includes stainless steel, low-temperature alloy steel, aluminum-magnesium alloy, Monel alloy and so on. Among them, stainless steel and non-ferrous metals account for about 5% 7% of the total consumables, and the most important thing is the cold heading wire. Cold heading steel wire rods and wire rods are usually low- and medium-carbon high-quality carbon layout steels and low-alloy steels. Low-carbon cold heading steel is mainly used for cold heading nuts. The materials of bolts and screws are mainly medium-carbon steel (ML35 and SWRCH35K), which can reach Grade 8 and above after quenching and tempering.

Cold heading is to manipulate metal plastic forming at room temperature. Cold heading function is one of the tense functions of cold heading steel. The important performance of its function is excellent cold formability; to deal with deformation, it must have as little resistance as possible and probably high deformation ability. Because of its excellent cold forming machine, cold heading steel uses cold drawing instead of hot-rolled material cutting machining in the machining industry. The advantage of this type of process is that it saves a lot of man-hours while reducing metal loss by 10%-30%, which is suitable for clean production , The capital-saving enterprise produces large-scale production, and the product has high dimensional accuracy, good general brightness, and high production compliance. It is the advanced machining technology that is promoted. Therefore, the use of cold forging technology to make fasteners not only has high obedience, good quality, but also saves materials and low cost.

Although the development of domestic cold-heading steel wire rod and wire rod started late, they have grown rapidly. Especially in the mid-1980s, high-speed wire rod production lines and wire rod continuous rolling production lines have been put into production. The production of upsetting steel wire and wire rod provides equipment guarantees. At the end of 2005, the production capacity of cold heading wire rod reached 6 million tons per year (approximately 1012% of the total wire rod amount).

The steel mills of Baosteel, Maanshan Iron u0026 Steel, Xing Steel, Xiangtan Iron and Steel, and Hangzhou Iron u0026 Steel, which have established cooperative relations with the fastener industry, have constituted the property group of my country's cold heading wire rods. The types of products include low carbon, ultra-low carbon, medium carbon (quenched and tempered), low-alloy alloy steel and general carburizing and softening steel. The specifications range from 5.5 to 42, almost covering fasteners. All steel is needed.

Stainless steel wire selection criteria for fasteners

For all bolts, screws, rivets, etc., in order to ensure safety, it is generally not necessary to consider the influence of temperature on the despicable environment or other harmful working conditions. Frequently used materials are carbon steel, low alloy steel and non-ferrous metals. However, in certain places, fastener materials must satisfy the preconditions of stress corrosion or high strength, and many stainless steels and ultra-high-strength stainless steels have emerged at the historic moment.

Most stainless steel materials can be made into steel wires or rods for fastener production, including austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, and precipitation softened stainless steel.