Factors Affecting Welding Temperature Field

    The factors affecting the welding temperature field can be summarized into the following main aspects.

    1. The influence of heat source

    Different heat sources affect the temperature distribution due to their different heat intensity (the amount of heat supplied per unit time) and heat distribution. The heat intensity of the arc is greater than that of the gas welding flame. Therefore, when welding materials of the same thickness, the temperature field of arc welding is smaller than that of gas welding. Moreover, the heat distribution of the arc is more concentrated than that of the gas flame, that is, the area affected by the heat is small, that is, the heat affected zone of the welding is small. In general, a small heat-affected zone is beneficial to the performance of welded joints. Therefore, the heat source (such as electron beam, plasma arc, etc.) with the greater the heat intensity and the more concentrated heat distribution is more promising in the welding process.

    2. Influence of basic metal thermophysical properties

    (1) Thermal conductivity (λ)

    Indicates the ability of a material to conduct heat, and the thermal conductivity of different materials varies greatly. The thermal conductivity of the same material also varies with temperature.

    (2) Specific heat (c)

    The amount of heat required to raise the temperature of a unit weight of material by 1°C. Different materials have different specific heats. Aluminum has a larger specific heat, carbon steel has a smaller specific heat, and copper is in between.

    Due to the different thermophysical properties of materials (mainly thermal conductivity, specific heat), the distribution of the temperature field is very different. The worse the thermal conductivity of the material, the larger the high-temperature heating area, that is, the larger the heat-affected zone that causes changes in tissue properties and deformation, and the more and more serious problems it often causes. But from another point of view, the material with poor thermal conductivity has high heat utilization rate of the heat source, and the welding melting efficiency is high.

    3. The influence of welding process parameters

    Among the welding process parameters, the arc rate and welding speed have a great influence. When the plate thickness and welding speed are constant, the arc power is large, and the high temperature area heated to 600°C increases. When the arc power and plate thickness are constant, increasing the welding speed reduces the high temperature region of 600°C. Therefore, we can properly adjust the welding process parameters and control the size of the heat affected zone.

    4. Influence of plate thickness

    The thickness of the material also has a great influence on the distribution of the temperature field. The larger the thickness, the faster the heat conduction, and the smaller the thickness, the slower the heat conduction. Therefore, under the same heat source power and process specification, the temperature field distribution range of the thick plate is smaller, and the temperature field distribution range of the thin plate is larger.

    5. Influence of the form of welded joints

    Different joint forms have different heat conduction. The joint with the easiest heat conduction has the smallest thermal field distribution (the ease of heat conduction is equivalent to the thermal conductivity of the material).

( huiputech)