High cleanliness spring steel and production method thereof

Abstract

The invention discloses a high cleanliness spring steel and a production method thereof. The production method includes pretreatment: desulfurizing molten iron to the extent that S≤0.0015% in molten iron; mixing molten iron and scrap steel into molten steel for desiliconization, dephosphorization, oxygen blowing and decarburization, and obtaining a temperature of 1630-1660° C., C 0.10-0.35 %, O≤0.045%, P≤0.011%, S 0.003~0.008% of molten steel, slag blocking and tapping and deoxidation alloying, the flow rate of argon blowing at the bottom of the ladle during tapping and after tapping is respectively 800~ 1000NL / min, 100~200NL / min; after that, the molten steel is refined to adjust the chemical composition and inclusions, and the flow rate of argon blowing at the bottom of the ladle is 300~500NL during the addition of slag and alloying treatment, when electrifying and heating up, and during the rest of the time. / min, 200~300NL / min, 50~100NL / min; then vacuum refining and air-breaking soft stirring are carried out in sequence, and the flow rate of argon blowing at the bottom of the ladle is 20~50NL / min, 50~100NL / min respectively; billet. In the high-cleanness spring steel prepared by the production method, the density of inclusions with a size of 5 μm or more is ≤ 0.5 pieces / mm 2 , the length-width product of the largest inclusion is less than or equal to 900 μm 2 , with high cleanliness.

Description

technical field [0001] The invention belongs to the technical field of iron and steel smelting, in particular to a high cleanliness spring steel and a production method of the high cleanliness spring steel. Background technique [0002] As a safety bearing component, springs are widely used in automobiles, machinery, railways and other fields. They often bear high-cycle alternating loads during service, and their failure mode is mainly fatigue fracture. Numerous studies have shown that inclusions are an important cause of fatigue failure. [0003] Due to the weak bonding force between the inclusions and the spring base, and the large difference in elastic modulus between the two, during the service process of the spring, the interface between the inclusions and the spring base will produce stress concentration. When the stress exceeds a certain range, the A crack source will form at the inclusion, and under the continuous alternating load, the crack will gradually expand, e...

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Problems solved by technology

In view of the spring steel prepared by the current production process in this technical field, there are problems such as large inclusion size and large number density of inclusions, so that the performance of the current existing spring steel cannot meet market demand

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