Control method of center loosening of φ280mm 30crmo round tube billet

Abstract

The invention discloses a center porosity control method for producing a 30CrMo circular tube blank with the diameter of the section being phi 280 mm and belongs to the field of metallurgy. The method comprises the steps of converter steel making, LF furnace molten steel refining, RH refining, molten steel continuous casting and the like, and the method is characterized in that a technology combining crystallizer electromagnetic stirring and solidification final stage electromagnetic stirring is adopted in the continuous casting stage. The center porosity control method has the beneficial effects that firstly, the purity degree of molten steel is increased and the optimal tapping condition of the molten steel is reached according to reasonable parameter control in the molten steel smelting stage; and afterwards, in the molten steel pouring process, the mode combining crystallizer electromagnetic stirring and solidification final stage electromagnetic stirring is adopted, so that ingredients and temperature of the molten steel are uniformized, a blank shell grows uniformly, and columnar crystal structures are continuously eroded and fused in the stirring process. Accordingly, the area of a center porosity zone of the casting blank is reduced, and the compactness is improved.

Description

technical field [0001] The invention relates to the field of iron and steel metallurgy, in particular to a method for controlling looseness in the center of a 30CrMo round tubular steel billet with a section of φ280 mm. Background technique [0002] 30CrMo billet steel is mainly used for the production of steel for oil well pipes used in oil and gas exploitation and transportation. P≤0.020%, S≤0.010%, V≤0.015%, Cr: 0.85%~1.05%, Mo: 0.17%~0.24%, Cu≤0.15%, Ni≤0.20%, Alt: 0.020%~0.040%, Residual element requirements: Nb≤0.010%, Ti≤0.010%, B≤0.005%, and V+Nb+Ti+B+Zr≤0.15%; As≤0.015%, Sn≤0.010%, Sb≤0.010%, Pb≤0.008 %, Bi≤0.010%, and As+Sn+Sb+Pb+Bi≤0.045%, and the balance is Fe. Under the joint action of stress and hydrogen sulfide gas during use, brittle fracture (called hydrogen sulfide stress corrosion) will occur suddenly when the stress is much lower than its own yield strength, which will easily cause problems such as production leakage, which is harmful to production and...

AI Technical Summary

Problems solved by technology

[0004] In order to overcome the disadvantages such as center porosity easily occurring in existing 30CrMo round tubular steel billets with larger section sizes, the technical problem to be solved by the present invention is to provide a method for controlling center loosening of 30CrMo round tubular steel billets with a cross section of φ280mm