Research on water-air plasma cutting process of carbon steel

Abstract

The principle and equipment of water-air plasma cutting have been introduced in this paper. Especially, the function of water is not only to prevent the cutting pool from oxidizing in the form of a water curtain but also to generate plasma in the center of the arc. The Numerical Model of Low temperature Plasma has been established with equations of energy, status, motion, and chemical dynamic equations. The working process, mechanical properties, and microstructural features of 20 mm carbon steel processed by water-air plasma cutting and air plasma have been investigated, which choose the same parameters. The voice of the plasma arc and the dust of the pool are being limited in the area of the water curtain so that the noise and dust of water-air plasma cutting can be compared favorably with underwater plasma cutting. The lower temperature of water-air cutting plates is due to the fluent water taking off energy from the metal pool during cutting. It is impossible to find an oxide layer on the incision surface of water-air plasma cutting, and the heat-affected zone is so thin that welding can be carried out directly after cutting without any other process. So inclusion also can be avoided in the weld. But for air plasma cutting, a lot of time is wasted to remove the oxide layer by mechanical polishing before welding. With the help of additional plasma arising from water, the water-air plasma arc becomes stronger, so a smooth and high-flatness cutting surface can be acquired. Compared with the technology of air plasma cutting, water-air plasma cutting has the benefits of a friendly working environment, higher quality incision, and lower cost.