Oveasea Production technology of spring steel
The production of spring steel in foreign countries started earlier and is more advanced than that in China in terms of production equipment, new process, new technology research and product quality control. For example, large electric furnace or blast furnace converter process is adopted for crude steel supply. When using electric furnace as primary smelting furnace, the scrap used is selected to ensure that the residual elements in crude steel are at a low level; Powder injection dephosphorization and slag free tapping technology are adopted for electric furnace; Vacuum slag removal of converter steel to reduce phosphorus content and prevent oxide slag from entering the refining furnace; RH vacuum degassing process is adopted on the basis of LF refining; The section size of continuous casting billet is generally larger than that of domestic special steel plants.
Some defects caused by casting are improved or eliminated through large compression ratio, and multistage electromagnetic stirring is adopted to reduce continuous segregation and forging defects; Liquid phase cavity reduction techniques such as light reduction, large diameter roll strong reduction and continuous forging are used to reduce segregation; In terms of finishing heat treatment, it has perfect finishing heat treatment equipment and quality assurance system.
Japan Datong special steel produces sup6, SUP7 and sup12 by combining ULO process. The specific steps of ULO treatment (ultra low oxygen treatment) are as follows: melt the molten steel in an over power alkaline electric arc furnace and blow argon, add Fe Si or Al to the molten steel for pre deoxidation treatment to obtain high alkalinity reduction slag.
Then pour the molten steel into the ladle, insert the two legs of RH circulating degassing equipment into the molten steel, and draw the molten steel into the vacuum chamber of degassing equipment. With the help of large capacity jet pump, keep the vacuum degree less than 13.3pa, introduce small flow argon into the molten steel, and the molten steel foams into the vacuum chamber.
The carbon deoxidation reaction in the molten steel is carried out quickly to deoxidize the molten steel. When the carbon oxygen reaction reaches equilibrium, Al deoxidizer is added. In order to promote the separation and removal of carbon and oxygen products and maintain the stability of deoxidation state, the deoxygenation operation is continued, and finally the amount of Al added is adjusted. After RH cycle degassing, the oxygen content decreased to about 15mg / L. In order to keep the oxygen content not greater than 15mg / L, the molten steel shall be kept free of oxidation during molten steel pouring and solidification to avoid pollution and promote the removal of deoxidation products.
Thyssen company of Germany achieved initial success in inclusion control of Si CR valve spring steel through efforts in 1993. Although the steel still contains 10 ~ 15LM inclusions, it does not exceed the maximum size of 15LM required by the spring manufacturer.
In 1989, Ipanema company of Brazil developed a vacuum deoxidation and desulfurization vrso treatment process for the production of ultra-low oxygen valve spring steel. The purity level obtained by this process is higher than that obtained by the traditional process used in vacuum degassing (VD) system. The average total oxygen content in steel can be reduced from 13.5mg/l to 8.4mg/l, and the total amount of micro inclusions can be reduced by more than 2 / 3.
Custom springs
Follows are some details for our springs.
