Annealing Process
Annealing is a commonly used heat treatment process to improve the distribution of welding residual stress. For Non-Standard Welding Parts, full annealing can heat the welded parts to an appropriate temperature, generally above the critical temperature, and slowly cool them after sufficient insulation time. During the heating process, the atoms inside the metal gain enough energy to become active, the lattice distortion originally caused by welding gradually recovers, and the residual stress is relaxed. For example, for some carbon steel Non-Standard Welding Parts, they are heated to 30-50℃ above Ac3, the insulation time is determined according to the thickness and size of the welded parts, and then slowly cooled with the furnace. This process can effectively reduce welding residual stress, improve the comprehensive performance of welded parts, improve their dimensional stability, and reduce the possibility of deformation and cracking. However, annealing will slightly reduce the strength and hardness of welded parts, and the pros and cons need to be weighed according to specific usage requirements.
Tempering Process
The tempering process is mainly used to eliminate residual stress after quenching or normalizing, and is also applicable to Non-Standard Welding Parts. Low temperature tempering is generally carried out between 150-250℃. The main purpose is to eliminate some residual stress and maintain high hardness and wear resistance. It is often used for some welded parts that require high surface hardness, such as tool steel Non-Standard Welding Parts. Medium temperature tempering at 350-500℃ can significantly reduce residual stress, while giving welded parts good elasticity and toughness. It is suitable for non-standard welded parts such as spring steel. High temperature tempering at 500-650℃ can greatly eliminate residual stress and achieve a good balance between the strength, plasticity and toughness of welded parts. It is often used for structural steel non-standard welded parts. The heating rate, holding time and cooling rate of tempering treatment need to be precisely controlled according to factors such as the material, shape and size of the welded parts to achieve the best residual stress elimination effect.
Aging treatment process
Natural aging is to place non-standard welded parts at room temperature for a long time, generally taking months or even years, using the changes in natural ambient temperature to allow atoms to diffuse naturally, thereby gradually eliminating residual stress. This method is simple, but the cycle is too long, and it is not suitable for welded parts that are urgently needed. Artificial aging is to heat the welded parts to a certain temperature and keep them warm for a period of time to accelerate the atomic diffusion process. For example, aluminum alloy Non-Standard Welding Parts are heated to about 100-200℃, kept warm for several hours, and then air-cooled, which can effectively reduce residual stress and stabilize the size and performance of the welded parts. Aging treatment is particularly important for some Non-Standard Welding Parts that have extremely high dimensional accuracy requirements and strong residual stress sensitivity. It can prevent deformation caused by residual stress release during subsequent processing or use.
Comprehensive considerations for selecting heat treatment processes
When choosing a heat treatment process to improve the residual stress distribution of Non-Standard Welding Parts, many factors need to be considered. First, the material of the welded parts should be considered. Different materials respond differently to heat treatment temperatures and processes. Secondly, the shape, size, and structural complexity of the welded parts. Complex shapes and large-sized welded parts may require special heating and cooling methods to ensure uniformity. Furthermore, the use requirements of welded parts, such as requirements for strength, hardness, toughness and other performance indicators, should be combined to weigh the impact of heat treatment process on these properties. At the same time, economic factors such as cost and production cycle should also be considered to select the most suitable and economical heat treatment process to ensure that Non-Standard Welding Parts meet performance requirements while residual stress is well improved, thereby improving its quality and reliability and extending its service life.
