1. A non-oxidation (nitrogen protected) roller hearth heat treatment furnace (normalized furnace) heated by
Radiant Tubes will develop nodules on the
Furnace Rollers after being used for a period of time. The direct harm of nodulation is to cause pockmarks in thicker steel plates. As shown in the figure below, it affects the surface quality. Please talk about effective measures to prevent nodulation on the hearth roller and how to deal with it after nodulation.
2. Casting has congenital deficiencies such as pores and blisters in the structure density. Drawing uses hot-rolled bar stock, and after multiple processes such as perforation and tube drawing, the uniformity and density of the ingredients are better than that of casting. , the price alone is much higher, regardless of the brand, so there is a big difference in price between stoves and stoves. It all sounds like the same material. The service life of drawn ones is much better.
3. Generally, protective atmosphere roller hearth furnaces will have the phenomenon of nodulation on the roller surface of the furnace roller. This is a difficult problem to solve. I asked SAC President Mr. Han Hengji and Mr. LOI Su. They think that the medium and thick plates are at the bottom of the roller. Nodulation in the furnace is mainly caused by surface impurities such as oxide scale coming into contact with the rollers at high temperatures. Once nodulation occurs, it will scratch the workpiece and aggravate the nodulation. The only solution is to add a shot blasting unit in front of the furnace to remove oxide scale and wash away steel shot and other impurities. Even if a shot blasting unit is added, there is no guarantee that no nodules will form at all, so regular inspections are required!
4. However, foreign experts say that it is better not to process the outer surface of the centrifugally cast roller, which can maintain a dense structure and has weak adsorption force on iron oxide scale or other impurities at high temperatures. However, the inner surface has been machined with an accuracy of 12.5 , which can effectively ensure the uniformity of the wall thickness of the roller.
