There are always some carbon elements in the stainless steel head, and carbon is iron. I believe that everyone has heard a saying that it is to take advantage of the heat to melt the iron in the high temperature and eliminate its magnetism. It is often said that the solution treatment.
After hot working, the stainless steel heads are not single-phase austenite, but also have a small amount of carbide. In order to obtain single-phase austenite and improve corrosion resistance, it can be heated at about IlOO C, so that all carbides are dissolved in austenite, and then water quenched to room temperature, that is to obtain single-phase austenite. This heat treatment, namely solid solution treatment (SHT), can improve the corrosion resistance of the material and soften the steel.
Because of its special shape, if the cooling method is improper, the stainless steel head may cause insufficient solid solution or serious deformation, which directly affects the quality of the product.
Heat treatment specification for solid solution treatment of stainless steel head
The heating rate should be as fast as possible. If the conditions are permitted, the air furnace can be heated to 1050 C, then the stainless steel head is placed in the furnace and then cooled. The holding time is usually controlled by 1mm/2 minutes, but at least 30 minutes, up to 60 minutes. If several stainless steel heads are heated together in the furnace, the second must rise again to 1050 degrees in the furnace, and then heat up for 5 minutes. From 950 to 550 C, it must be controlled within 3 minutes.
Stainless steel head
The operation method of solid solution treatment for stainless steel head
The stainless steel head with a diameter of less than lOOOmm is cooled by lifting the lifting lug after driving.
For stainless steel heads with larger diameters and openings on the curved surfaces, the opening of holes on the surfaces of stainless steel heads should be subject to customer’s consent. The diameter of the general hole should be more than 30mm. In order to achieve better cooling effect, several vent holes can be opened. After discharge, the lifting lug horizontal position is immersed in water to cool down.
For a stainless steel head with a larger diameter and no opening, the exhaust pipe is usually welded with two seamless steel pipes with a diameter of 80mm. The pipe is immersed in the water with a crane and the top of the exhaust pipe must be exposed to the water.
Among the above three methods, the function of the tooling board is to control the change of the size of the stainless steel head. The thickness of the plate plate should be more than 30mm, the thicker the stainless steel head, the thickness of the tooling board should be correspondingly thickened. The welding of the tooling plate and the stainless steel head must be firm. Once the welding is not stable, if the welding process is undone during the cooling process, it may cause the deformation of the stainless steel head. The strength of the hanging ear should also be considered, because the strength of the steel plate may be only 1/10 at normal temperature when heating to 1050 C. In order to prevent problems during the lifting process, the strength of the hanger and the welding of the hanger must be confirmed.
After the stainless steel head is immersed in the water, the water on the surface of the stainless steel head should be continuously flowing to prevent the formation of water film on the surface of the stainless steel head and the cooling rate of the stainless steel head.
Source: China Stainless Steel Head Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)