Oxidation treatment method of hot-rolled seamless pipe

The oxide film on the surface of the hot-rolled seamless pipe is thin and high in density, and it is not easy to fall off. Under normal circumstances, the hot-rolled seamless pipe will cause 0.2-0.3mm oxide scale in the heat treatment equipment, and the casting defects in this range will be It can be removed with the oxidation of galvanized iron. If the defects are not within this range, the surface defects on the billet will inevitably be brought into the final product if they are not treated in all aspects. Hot-rolled seamless pipes generally cannot use flame to eliminate the surface defects of the billet. Flame elimination will cause changes in the composition and crystal phase composition of the region where the billet is eliminated, which will affect the corrosion resistance of stainless steel sheets. Therefore, industrial equipment elimination is a widely effective method for the metal surface treatment of stainless steel sheets. The general methods include cleaning mechanical treatment of oxidized galvanized iron, water blasting, and shot blasting machine elimination.

The first one, cleaning mechanical treatment of oxidized galvanized iron

The galvanized iron cleaning machine is mainly composed of steel brush roller, controller equipment, high pressure water system, refrigeration system and clamping equipment. Two rollers with stainless steel wires (called steel brush rollers) are installed on the roller seat, and the steel brush rollers run at high speed in the opposite direction of the slab running. Oxidized galvanized iron on the surface.The galvanized iron oxide cleaning machine can use more steel grades, but the elimination of the oxidized galvanized iron is not thorough enough.

The second type, the water burst pool

The water blast pool uses the refrigerating and cooling circulating water at room temperature as the refrigeration chemical substance, puts the high-temperature billet into the water storage tank, and uses "water blast" to remove the oxidized galvanized iron on the surface of the billet. The basic concept is that when the water encounters the high temperature billet, it vaporizes in an instant, resulting in a "water explosion", resulting in a lot of high-pressure steam. The impact force of the steam acts on the surface of the billet to make the oxidized galvanized iron fall off. In addition, the cast billet and the oxidized galvanized iron on its surface are greatly cooled by water under high temperature conditions, resulting in a shrinkage stress field. Due to the different stress field specifications between the cast billet and the oxidized galvanized iron on its surface, the oxidized galvanized iron cracks and falls off.The water explosion pool has low investment projects, less maintenance and low cost of production, processing and operation. However, fewer steel grades can be used, and only a part of austenitic stainless steel sheets, such as 301, 304 and other steel grades, can be used.

The third type, shot blasting machine eliminates

Shot blasting machines are mostly used to eliminate the oxidation of galvanized iron on the surface of the billet. The shot blasting machine is mainly composed of a sandblasting and derusting room, a grinding rod, a sandblasting and derusting conveying system, a shot removal machine and equipment, a shot compensation device, a dust collector, an air inlet and an automatic control system for electrical equipment. The basic principle is to use the spring steel shot thrown out by the shot blasting machine to oxidize the galvanized iron on the surface of the destructive casting billet to make it fall.