Reflow wire: Process optimization shows advantages, applicable to both construction and packaging fields

Tempered wire, usually made from steel wire through tempering treatment, plays a crucial role in numerous industries such as industry, machinery, and packaging. Its unique properties stem from specific processing techniques, enabling it to perform indispensable functions in various fields.
From the perspective of production processes, taking oil quenching - tempering steel wire as an example, the steel wire that has been drawn to the final size needs to undergo quenching and tempering successively in a continuous furnace. The wire is first heated to the complete austenitization temperature in the continuous furnace, then quenched in an oil bath to form a martensitic structure, and finally tempered in the continuous furnace to obtain the desired strength and toughness. This process enables oil quenching - tempering steel wire to have good straightness and uniform mechanical properties, and after being made into components or parts, only low-temperature stress relief treatment is required for them to be put into use. Pre-hardening treatment, as a special form of oil quenching - tempering, is often used for the heat treatment of cold working steel wire, hot working steel wire, and plastic working steel wire, etc. for finished products. Due to the high carbon and alloy element content of such steel wires, not only must the austenitization heating temperature be increased and the holding time be extended, but also multiple tempering methods must be adopted to promote the decomposition of residual austenite and ensure that the steel wire reaches the predetermined hardness.
The performance advantages of tempered wire are remarkable. In the spring manufacturing field, the metallographic structure of oil quenching - tempering spring steel wire is uniform, presenting tempering martensite or tempering sorbite, with the characteristic of isotropy. Under the same tensile strength conditions, compared with cold drawn steel wire, its elastic limit is higher, the elastic straightening performance is better, and the stress relaxation and creep resistance are also better. For example, when the relaxation rate of cold-drawn carbon steel wire is ≤ 6.0%, the maximum working temperature is 120℃, while oil quenching - tempering carbon steel wire can reach 150℃. Some alloy steel wires such as 50CrV, 55CrSi, and 60Si2MnA, the maximum working temperature is even increased to 200℃ and 250℃ respectively. Springs wound with oil quenching - tempering steel wire, after stress relief tempering, can be directly used, simplifying the production process and reducing costs, while the surface decarburization phenomenon is reduced, the mechanical property uniformity is improved, and the fatigue life is significantly increased.
In practical applications, tempered wire can be found everywhere. In automotive manufacturing, tempered tire bead wire is used to enhance the structural strength of tires and ensure driving safety; valve springs, suspension springs, and other key components often use oil quenching - tempering spring steel wire to meet the strict requirements of spring performance under complex automotive working conditions. In the construction industry, annealed wire is often used due to its flexibility and elasticity, and is used for binding steel bars to provide support for building structures. In the packaging industry, tempered wire can be made into binding wires for waste paper packaging and vegetable greenhouse fixation, due to its good flexibility and certain strength, it can effectively achieve the binding and fixation of items.
However, tempered wire is not perfect. Improper tempering of tempered wire can lead to oxidation and decarburization on the surface, which will seriously affect its fatigue life; at the same time, the steel wire is highly sensitive to hydrogen embrittlement and has slightly poorer stress corrosion resistance, and its application in some special environments may be limited.
With the continuous advancement of technology, the production process and performance of tempered wire are also continuously optimized. On one hand, production enterprises improve the quality stability and production efficiency of tempered wire by improving heat treatment equipment and process parameters; on the other hand, researchers continuously explore new alloy formulations and surface treatment technologies to enhance the comprehensive performance of tempered wire and meet the needs of more emerging fields. It is believed that in the future, tempered wire will, with its unique advantages and continuous innovation in technology, play a greater role in more industries and provide strong support for the development of various fields.