Effect Of Heat Treatment On Corrosion Resistance Of V150 Drill Steel

Drill pipe is an important tool for oil and gas exploitation and with the increasing number of oil and gas fields which has higher sulfur content being discovered in recent years, the requirements of drill pipe corrosion resistance to hydrogen sulfide have become stricker. Aimed the anti-corrosion requirements of drill pipe in the acidic environment and on the base of improving service life of drill pipes, in this article, the method of heat treatment for V150drill pipe body material has been chosen, after which it need to conduct the microstructure, mechanical properties test, hydrogen sulfide stress corrosion test(SSCC), and hydrogen sulfide hydrogen induced cracking (HIC) test to study the microstructure, mechanical properties, electro-chemical corrosion property, SSC performance and HIC performance of drill pipe body material after different heat treatment.Microstructure and mechanical properties test showed that:the microstructure is mainly tempered sorbite after different heat treatment. When the quenching temperature is determined, the higher the tempering temperature is, the tensile strength, yield strength and hardness is smaller, while the impact toughness is bigger。Electrochemical test showed that the order of corrosion tendencies in A solution of drill pipe body materials after different heat treatment was:735a<705a<725a<715a. The order of anti-corrosion was:715a<725a<705a<735a. The order of corrosion tendencies in B solution of drill pipe body materials after different heat treatment was:715b<735b<725b<705b. The order of anti-corrosion was:705b<725b<7305b<715b. Therefore. the resistance corrosion of735sample in A and B solution was better.SSC test showed that the corrosion time of700sample was the shortest while735sample was the longest. Therefore, under certain circumstances quenching temperature, with the increase of tempering temperature, the SSC performance is better. In conclusion,900℃×90min(insulation)+water quenching+735℃×120min (insulation)+air-cooled heat treatment process can improve the anti SSC performance of the drill pipe body material.HIC test showed that drill pipe body material after different heat treatment had good resistance to HIC because all the samples didn’t encounter hydrogen induced cracking through standard96hHIC test. In dehydrogenation HIC test, there were no bubbling hydrogen and hydrogen-induced cracking on the samples. After192h and384h HIC test, there was also no bubbling hydrogen and hydrogen-induced cracking occurred on all the samples. The order of HIC resistance strength was:B705<B715<B725<B735.Thus, the HIC performance became poor with extending the time of corrosion.900℃×90min (insulation)+water quenching+735℃×120min (insulation)+air-cooled heat treatment process can efficiently improves the HIC performance.