Mechanical Work and Recrystallization Zone in Centrifugally Cast Alumina-forming Alloys Designed for Coking Resistance
Mentor 1
Benjamin Church
Location
Union Wisconsin Room
Start Date
27-4-2018 1:00 PM
Description
In the petrochemical industry, hydrocarbons are cracked at very high temperatures to produce ethylene gas and other products. Steel alloys used in the pipes and cracking reactors need both superior corrosion and creep resistance as well as coking resistance. Recently, studies have shown that alumina-forming austenitic stainless steels have superior oxidation resistance making them suitable for a wide range of energy production, chemical, and process industry applications.
A series of alumina-forming alloys produced via centrifugal casting process were received as sections of pipe. Following horizontal centrifugal casting, the cast tubes were pull-bored to machine the inner diameter. The inner diameters of the tubes were pull bored and the outer diameter was left in the as-cast condition. This production process used is identical to that used to produce production tubes for ethylene service.
The project involves the analysis of the near-surface hardness and understanding if the boring (machining of the ID) is imparting cold work to the material that would potentially provide the means for recrystallization near the ID of the tube. Samples were annealed at 500°C and 1000°C and compared to the as-cast pipe section alloy. Nanohardness tests were done to evaluate mechanical work on the inner diameters of the pipes during boring process as well as optical microscopy study of the recrystallization zone after heat treatment process to better identify corrosion-prone regions.
Mechanical Work and Recrystallization Zone in Centrifugally Cast Alumina-forming Alloys Designed for Coking Resistance
Union Wisconsin Room
In the petrochemical industry, hydrocarbons are cracked at very high temperatures to produce ethylene gas and other products. Steel alloys used in the pipes and cracking reactors need both superior corrosion and creep resistance as well as coking resistance. Recently, studies have shown that alumina-forming austenitic stainless steels have superior oxidation resistance making them suitable for a wide range of energy production, chemical, and process industry applications.
A series of alumina-forming alloys produced via centrifugal casting process were received as sections of pipe. Following horizontal centrifugal casting, the cast tubes were pull-bored to machine the inner diameter. The inner diameters of the tubes were pull bored and the outer diameter was left in the as-cast condition. This production process used is identical to that used to produce production tubes for ethylene service.
The project involves the analysis of the near-surface hardness and understanding if the boring (machining of the ID) is imparting cold work to the material that would potentially provide the means for recrystallization near the ID of the tube. Samples were annealed at 500°C and 1000°C and compared to the as-cast pipe section alloy. Nanohardness tests were done to evaluate mechanical work on the inner diameters of the pipes during boring process as well as optical microscopy study of the recrystallization zone after heat treatment process to better identify corrosion-prone regions.
