针对不同厚度50Mn钢板火焰切割取样过程中，取样范围较难确定的问题，通过试验和数值模拟研究了5 mm厚度50Mn热轧钢板在氧-乙炔火焰切割条件下热影响区的范围，并进行了硬度试验来验证模拟精度；利用热力学分析软件FLUNT对不同厚度50Mn钢板火焰切割过程进行温度场模拟，得到了不同厚度50Mn钢板火焰切割的热影响区范围；最后对热影响区宽度和钢板厚度进行了线性拟和，确定了最小加工余量Y与50Mn钢板厚度x的关系为Y=1+int（10.31+0.11x）。

In order to solve the problem that it is difficult to determine the sampling range in the flame cutting sampling process of 50Mn steel plates with different thickness, the range of the heat affected zone of 5 mm thickness 50Mn steel plates under oxygen-acetylene flame cutting conditions was studied by experiment and numerical simulation, and the simulation accuracy was verified by hardness test. The temperature field of 50Mn steel plates with different thickness during flame cutting process was simulated by using the software FLUNT, and the range of the heat affected zone in flame cutting of 50Mn steel plates with different thickness was obtained. The width of the heat affected zone and the thickness of the steel plates were linearly fitted, and the relationship between the minimum machining allowance Y and the thickness of 50Mn steel plates x was Y=1+int(10.31+0.11x).