Analysis of corrosion fatigue steel strength of pump rods for oil wells

IF 2.8 Q2 MINING & MINERAL PROCESSING

Mining of Mineral Deposits Pub Date : 2022-09-30 DOI:10.33271/mining16.03.031

Yurii Vynnykov, M. Kharchenko, S. Manhura, H. Muhlis, A. Aniskin, A. Manhura

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引用次数: 2

Abstract

Purpose is to perform analysis of corrosion durability (fatigue) of pump rod materials in terms of various chemically active simulation environments, and study influence of economically modified rare-earth impurity on corrosion fatigue strength of pump rod materials. Methods. 40 and 20N2M steel grades have been applied as well as experimental steel (ES). Steel of the conditinal ES grade has been melted within a pilot site of Institute of Electric Welding Named after E.O. Paton of the National Academy of Sciences of Ukraine. The steel was alloyed economically by means of a micro impurity of a rare-earth element (REE) being 0.03% of cerium; in addition, it contained comparatively low concentration of sulfur and phosphorus as well as minor concentration of dissolved hydrogen. The following has been used as simulation environments: 1) NACE environment (i.e. 5% NaCl solution which contained 0.5% СН3СООН, and saturated H2S; t = 22 ± 2°C; pH = 3.8-4.0); 2) 3% NaCl solution without hydrogen sulphide. Once every day, the environment was replaced to oxygenate it up to 8-10 mg/l concentration. Findings. Stability against sulfide stress-corrosion cracking (SSCC), hydrogen initiated cracking (HIC), and corrosion fatigue of steel of deep pump rods for oil industry has been studied. It has been defined that the experimental steel, modified economically by means of micro impurities of a REE, meets NACE MR0175-96 standard in terms of chemical composition as well as strength; in turn, 20N2M and 40 steel grades have high resistance neither to SSCC (threshold stresses are < 0.8 s) nor to corrosion fatigue attack; moreover, steel grade 40 has demonstrated low resistance to HIC (CLR > 6% and CTR > 3%). Originality. It has been identified that corrosion fatigue attack results from hydrogen penetration of steel initiating its cracking and hence destruction under the effect of alternating loads accelerated by the action of corrosive environment. Further, surface micro destructions, influenced by micro stresses, transform into large discontinuities and cracks with following macro destructions. Practical implications. It has been proved that high resistance to corrosion cracking can be achieved by means of refining of pump-rod steel of ferrite and perlite type using metallurgical methods, i.e. 0.01-0.03% REE microalloying.

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油井抽油杆腐蚀疲劳钢强度分析

目的是在各种化学活性模拟环境下对泵杆材料的腐蚀耐久性（疲劳）进行分析，并研究经济改性稀土杂质对泵杆材腐蚀疲劳强度的影响。方法。40和20N2M钢以及实验钢（ES）已经被应用。在以乌克兰国家科学院E.O.Paton命名的电焊研究所的一个试验场地内，条件ES级钢已经熔化。钢通过稀土元素（REE）的微量杂质（铈的0.03%）经济地合金化；此外，它含有相对较低浓度的硫和磷以及少量的溶解氢。以下被用作模拟环境：1）NACE环境（即含有0.5%СН3СООН和饱和H2S的5%NaCl溶液；t=22±2°C；pH=3.8-4.0）；2）不含硫化氢的3%NaCl溶液。每天更换一次环境，使其氧化至8-10mg/l的浓度。调查结果。研究了石油工业用深抽油杆钢抗硫化物应力腐蚀开裂（SSCC）、氢致开裂（HIC）和腐蚀疲劳的稳定性。已经确定，通过REE的微量杂质经济地改性的实验钢在化学成分和强度方面符合NACE MR0175-96标准；20N2M和40级钢对SSCC（阈值应力<0.8s）和腐蚀疲劳攻击都没有很高的抵抗力；此外，40级钢的抗HIC能力较低（CLR＞6%，CTR＞3%）。独创性已经确定，腐蚀疲劳攻击是由钢的氢渗透引起的，在腐蚀环境作用下加速的交变载荷作用下，钢开始开裂，从而破坏。此外，表面微破坏在微应力的影响下，转变为大的不连续性和裂纹，并伴随着宏观破坏。实际意义。事实证明，采用冶金方法，即0.01-0.03%REE微合金化，对铁素体和珍珠岩型抽油杆钢进行精炼，可以获得较高的耐腐蚀开裂性能。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Mining of Mineral Deposits MINING & MINERAL PROCESSING-

CiteScore

5.20

自引率

15.80%

发文量