Abstract: Based on the idea of combination of equation and graph, welding temperature field was analyzed by example plate analytical solution under the action of mobile line heat source. The three-dimensional distribution graph and the two-dimensional temperature and isotherm curve of the temperature field of the infinite plate were accurately drawn. The results showed that the temperature increases slowly and then decreases rapidly with x variation when y takes a fixed value. The highest temperature point moves slowly to the left with the increase of y value. The temperature is symmetric about straight line y=0 mm when x takes a fixed value and takes a maximum value when y=0 mm. A single isotherm is similar to an ellipse and is symmetric about its horizontal axis. The front of the temperature field has dense lines and large temperature gradient, while the back of the temperature field has sparse lines and small temperature gradient. Then the surface shape and size of welding pool in the case of example are calculated, the molten pool looks like an ellipse and is 30.16 mm long, 22.13 mm wide.

Key words: infinite plate, welding temperature field, analytic solution