Spring steel has good elasticity, and because it works under dynamic load environmental conditions, the most important material for manufacturing springs should have high yield strength; it should not cause plastic deformation when subjected to heavy loads; it should have high yield strength. Fatigue strength, long service life under repeated loads; and sufficient toughness and plasticity to prevent sudden brittle fracture under impact force.
The quality of spring steel: the larger the steel element (carbon, sulfur), the higher the isolation. When the carbon content is greater than 0.45%, the isolation degree of the content isolation increases rapidly, even electromagnetic stirring measures, high carbon content and relatively large isolation parts. Steel vacuum can remove [H], [Ø], [的], the removal of inclusions, and even the composition and temperature of molten steel can also close part of the carbon at the same time, thereby improving the purity of steel, thereby helping to reduce macro-segregation Of carbon and sulfur.
Spring steel refers to steel specially used for manufacturing springs and elastic elements due to its elasticity in the quenched and tempered state. The elasticity of steel depends on its elastic deformation ability, that is, within the specified range, the elastic deformation ability makes it bear a certain load, and no permanent deformation occurs after the load is removed.
Spring steel should have excellent comprehensive properties, such as mechanical properties (especially elastic limit, strength limit, yield ratio), elastic reduction properties (that is, elastic reduction resistance, also called relaxation resistance), fatigue properties, hardenability , Physical and chemical properties (heat resistance, low temperature resistance, oxidation resistance, corrosion resistance, etc.). In order to meet the above performance requirements, spring steel has excellent metallurgical quality (high purity and uniformity), good surface quality (strict control of surface defects and decarburization), accurate shape and size.
Spring steel produced by electric furnace steel is generally used, but it has a long production cycle, low output and high energy consumption. Two technologies are used to produce 60Si2Mn spring steel and compared: converter→LF furnace→continuous casting→venere; converter→LF furnace→continuous casting. Taking into account the effect of overheating on the growth of large columnar crystals, even mild overheating is prone to branch “bridging” phenomenon. “Small ingots” are loose and segregated from the center to cause the formation of the structure. When the degree of overheating increases, the diversion hike is in full bloom. In this test, in a larger overheating, the isolation plate after vacuum refining is not reduced, which shows that the level of center segregation of spring steel continuous casting billet can be improved by vacuum refining.
1) During the converter smelting process of spring steel 60Si2Mn steel, the center of vacuum refining, improving the quality of the cast billet, and reducing carbon dioxide and sulfur played an important role in isolation.
2) Vacuum refining may be due to the reduction of the carbon segregation index of spring steel billets from 1.72 to 1.28.
3) The spring sulfur segregation index of vacuum refining steel slab dropped from 2.68 to 1.68.