QuesTek senior materials design engineer Gary Whelan was recently interviewed by Pipeline & Gas Journal for an article detailing innovations in corrosion control and pipeline coating for oil and natural gas pipelines. 
Gary shared how the physics-based modeling approach employed by QuesTek’s ICMD® digital materials design and engineering platform can be used to create more resilient alloys, reducing or eliminating the need for coatings.
See Gary’s section of the article below, and also check out his recent piece on structural stress cracking for PGJ.
Different types of alloys can be considered high-performing for use in pipelines.
“Generally speaking, there is a spectrum of alloys that can be used for transporting hydrocarbons, depending on how corrosive the hydrocarbons are,” said Gary Whelan, a senior materials design engineer at QuesTek Innovations. “If the hydrocarbons are relatively non-corrosive, simple carbon-steel can be used, and as the corrosiveness increases, you would want to include more chromium, tending toward stainless steel, which is inherently more expensive but also higher performance.”
He added that for highly corrosive hydrocarbons we might consider nickel alloys, which are sometimes referred to as corrosion-resistant alloys in the oil and gas business.
Whelan has experience using integrated computational materials engineering (ICME), to model process-structure-property relationships for metal alloys of various material classes, including steel, aluminum, nickel and titanium. His research has primarily focused on physics-based simulation and machine learning applied to fatigue in metallic components, with an emphasis on additive manufacturing.
Among the innovative products that have been developed recently, which enhance corrosion control and provide better pipeline coatings, are ones focused on ICME — a methodology developed over the past 10–20 years to utilize physics-based modeling and simulation to predict process-structure-property relationships in materials.
“This approach is useful in developing coating technology, but more importantly, it is useful in developing high performing alloys, which in many cases subvert the need for coatings in challenging environments like pipelines,” said Whelan.
ICME has been used to develop high-strength corrosion resistant alloys for many applications including those in the oil and gas industry Recently QuesTek used this methodology in a software tool called simply ICMD®, which is a user-friendly, web-based environment for engineers to use resolving materials challenges.
Whelan noted that additional research is underway on ways to enhance corrosion control and pipeline coatings and on the effects of various alloying elements on general corrosion resistance and grain boundary cohesion in metal alloys.
“Particularly for the latter, there are density functional theory (DFT) simulations and atom probe experiments that can predict and measure the segregation of alloying elements to grain boundaries in metal alloys,” Whelan said, as well as “predicting the effects of those elements on the cohesion of grain boundaries when they are present in high densities.”
He described these efforts like a ball at the top of a hill.
It is kinetically more favorable for the ball to be at the bottom of the hill, so it will tend to roll down the hill; however, if you make the hill less steep, make it sticky or add impediments along the hill to stop the ball, then you can prevent the ball from rolling down the hill.
“In the case of corrosion cracking, hydrogen wants to make free surfaces out of grain boundaries, which means grains separating, which is a form of the overall material cracking,” he said.
This tendency for hydrogen to make grains separate more easily makes the material brittle. The current research focuses on adding impediments to this process, by alloying the metal with elements that will take up all of the spots at the grain boundary and act as cohesive forces to hold the grain boundary together.
The current research focuses on understanding how each element behaves in common materials like steel, nickel, and aluminum, so that we can better design new alloys which are resistant to corrosion cracking, he added.
Read the full article in Pipeline & Gas Journal.