High-strength tough titanium alloy drill stem material friction welding method

Abstract

The invention discloses a high-strength tough titanium alloy drill stem material friction welding method. A titanium alloy drill stem comprises ingredients including, by weight, 5%-7% of Al, 2.0%-3.0% of Nb, 0.5%-2.0% of Zr, 0.7%-1.2% of Mo, 0.02%-0.05% of Fe, 0.01%-0.03% of Si and the balance Ti; and the friction welding method of the titanium alloy drill stem using the above compositions includes the steps that (1) a connector is rotated; (2) pressure is applied; (3) friction welding is carried out; and (4) welding seam induction heat treatment is carried out. The high-strength tough titanium alloy drill stem material friction welding method has the beneficial effects that the combination properties obtained after titanium alloy drill stem material friction welding can meet the conditions that the strength of extension is larger than 900 MPa, and the yield strength is larger than 800 MPa; the 10 mm*10 mm longitudinal ballistic work of a welding seam at 21 DEG C can reach higher than 36 J; the welding seam hardness is smaller than 32 HRC; H2S partial pressure can be 5 Mpa, the CO2 partial pressure can be 11 Mpa, the NaCl concentration is 100000 ppmCl, the elemental sulfur shows far higher sulfuretted hydrogen stress corrosion resistance compared with a common API drilling stem when used in the 3 g / L rigor corrosion environment, the drilling stem is the best material for replacing steel in oil and gas exploitation, and the corrosion environment oil field requirement is met.

Description

technical field [0001] The invention relates to the technical field of drill pipe materials for drilling, in particular to a friction welding method for high-strength and toughness titanium alloy drill pipe materials. Background technique [0002] In oil well tubular products, since the drill pipe directly bears the complex combined load of bending, torsion, compression and tension during the drilling operation, the safety of its oil field service is very important. According to the experience in the oil field, the failure of the drill pipe is mainly reflected in the two parts of the weld and the inner thickened transition zone. Friction welding is considered to be the most reliable method of joining oil drill pipe body and drill pipe joint. It is very important to research and develop a welding process suitable for titanium alloy drill pipe products. Welded joints have the problem of low strength and toughness. At present, the most common solution is to perform post-weld ...

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Problems solved by technology

At present, there is no mature welding and post-weld heat treatment process for titanium alloy drill pipe products in China

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