This paper presents a numerical model of the laser welding of steel, taking into account the heat and mass flows, as well as thermal effects associated with phase transformations. It was assumed that the heat source is a laser with a symmetrical power distribution of the TEM₁₀ beam in two welding condition variants: a stationary heat source and a source moving at a constant speed along the sample. After reaching the melting temperature, the movement of the liquid phase was forced by the Marangoni effect acting on the surface of the welding pool. For the laser power applied, the surface of the welding pool was assumed to be flat. It was proposed an algorithm for the forecasting of the phase changes during heating and cooling. Diffusive phase transformations during cooling were modelled using Johnson-Mehl-Avrami-Kolmogorov (JMAK) equations. Diffusionless transformations occurring when cooling rates exceed the critical ones were modelled using Koistinen-Marburger (KM) equations. Calculations were made for a rectangular sample welded in air and cooled spontaneously in the atmosphere. The boundary conditions were simulated assuming a constant coefficient of heat exchange and radiation to the environment. The start and end time of the changes occurring in the cooling phase were calculated based on the average cooling rate in the temperature range 800–500°C (v_8/5). The model was tested for the test material: S355J2 steel.

本文介绍了钢激光焊接的数值模型，考虑了热流和质量流，以及与相变相关的热效应。假设热源是具有对称功率分布的 TEM ₁₀两种焊接条件变体中的光束：固定热源和沿样品以恒定速度移动的源。达到熔化温度后，由于作用于熔池表面的马兰戈尼效应，液相的运动被迫进行。对于施加的激光功率，假定焊池表面是平坦的。提出了一种用于预测加热和冷却过程中相变的算法。冷却过程中的扩散相变使用 Johnson-Mehl-Avrami-Kolmogorov (JMAK) 方程建模。使用 Koistinen-Marburger (KM) 方程模拟冷却速率超过临界值时发生的无扩散变换。对在空气中焊接并在大气中自然冷却的矩形样品进行计算。假设对环境的热交换和辐射系数恒定，模拟边界条件。根据800-500°C温度范围内的平均冷却速率计算冷却阶段发生变化的开始和结束时间（v _8/5）。该模型的测试材料为：S355J2 钢。