Steel for non-magnetic drilling tool and production method thereof

Abstract

The invention discloses steel for non-magnetic drilling tools and a production method thereof. The steel for non-magnetic drilling tools comprises the following chemical compositions in percentage by weight: Fe, less than or equal to 0.06% of C, 17.00-23.00% of Mn, less than or equal to 0.80% of Si, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 12.00-20.00% of Cr, less than or equal to 1.0% of Mo, 0.20-1.20% of N, less than or equal to 2.30% of Ni and less than or equal to 0.025% of Al, wherein, N equivalent weight=Ni+0.6Mn+0.18Cr+9.69(C+N)-0.11SI2 is greater than or equal to 16. Compared with the prior art, the invention provides an economic and scientific production method with stable austenite so as to be subject to use requirement, production cost requirement and the like. The steel for non-magnetic drilling tools of the invention is also suitable for other applicable fields.

Description

(1) Technical field [0001] The invention belongs to the technical field of steelmaking and forging, and in particular relates to a steel for non-magnetic drilling tools and a production method thereof. (2) Background technology [0002] The controllable directional drilling technology of oil production needs to precisely control the orientation of the borehole, which is usually positioned by a magnetic compass or other magnetic instruments. If ferromagnetic components are placed near these positioning instruments, the positioning will be disturbed. Therefore, in One or several non-magnetic drilling tools must be installed on each drill string to facilitate directional drilling. The purpose of configuring a non-magnetic drill collar near the position of the magnetic compass is not to provide a magnetic field-free environment for the magnetic compass, but to make the magnetic compass free from the influence of the close ferromagnetic drill string. If the magnetic compass is i...

AI Technical Summary

Problems solved by technology

However, there are the following problems: if the amount of RE added is too large, it is easy to generate a large number of rare earth oxide inclusions in the steel, which reduces the plasticity and intergranular corrosion resistance of the steel; if the Si content is too high, the solubility of N in the steel will be reduced. Encourage the formation of δ ferrite, so that the relative magnetic permeability of the steel exceeds the standard; the Nb content is too high, and it is easy to form many strips and massive Nb carbon and nitride precipitation, and when the carbon content is high, the carbon and nitrogen in Nb Around the compound, the carbon and nitrogen compounds of Cr are precipitated, which reduces the intergranular corrosion resistance of steel

In this patent, the Nb content is not more than 0.35%, and the niobium in the examples is 0.29-0.32%. In this case, many strips and massive Nb carbons and nitrides will be precipitated, and Cr will be formed around the Nb carbons and nitrides. Precipitation of carbon and nitrogen compounds reduces the intergranular corrosion resistance of steel

The stainless steel produced by this patent is medium and high-nitrogen stainless steel. Its manufacturing process adopts electric furnace-LFV refining or electric furnace-AOD refining-LFV refining, but the vacuum refining in the later stage of smelting will reduce the solubility of nitrogen in the steel, resulting in A large amount of precipitation, so the smelting process is contradictory to the characteristics of the patented steel, which is not conducive to reducing costs and improving quality