Corrosion-Fatigue Assessment of Martensitic Stainless Steel and High Strength Low Alloy Steel Sucker Rod Materials in Harsh Environments

Abstract

The cyclic nature of the operations with sucker rods makes the fatigue life one of the most desired characteristics for these products. Production in aggressive service environments with higher acid gas concentrations associated with increased levels of hydrogen sulfide (H2S) and carbon dioxide (CO2) requires good fatigue life with the potential for corrosion. This combination makes corrosion-fatigue the primary mechanism responsible for sucker rod failures in reciprocating artificial lift applications.

High Strength Low Alloy (HSLA) steels have been widely used in decades to provide fatigue resistance, however the corrosion resistance of such steels is of concern. High-chromium steels have recently been utilized to improve performance, but their corrosion resistance is limited along with their fatigue performance.

The development of a new martensitic stainless-steel grade aims to improve corrosion resistance, extend fatigue life of sucker rods and reduce overall operating costs. The combination of selected chemistry with well-defined process variables and heat treatment parameters is key to provide a product with optimum properties that includes fatigue life with needed mechanical properties, toughness and grain structure.

This paper presents the results of different high strength low alloy steels compared to a targeted stainless steel in corrosive environments.