Residual Stress Evolution in Low-Alloyed Steel at Three Different Length Scales

Area of Science:

• Materials Science
• Metallurgy
• Solid Mechanics

Background:

• Residual stresses significantly impact the performance and integrity of steel components, particularly in demanding environments like sour gas applications.
• Understanding residual stress evolution during heat treatment is critical for predicting material behavior and ensuring component reliability.

Purpose of the Study:

• To investigate the quantitative and qualitative evolution of residual stresses in low-alloyed steel during heat treatment.
• To analyze residual stress development across three distinct length scales: component, interdendritic segregation, and precipitate.
• To provide insights for optimizing steel design for sour gas-resistant seamless steel tubes.

Main Methods:

• A continuum model was employed to simulate macroscopic temperature, phase, and stress evolution during heat treatment.
• A mesoscopic submodel was utilized to analyze strain and temperature variations influenced by interdendritic segregation.
• Precipitates were categorized based on their propensity to form microscopic residual stresses.

Main Results:

• Macroscopic residual stresses up to 700 MPa can develop after rapid cooling, contingent on the cooling process.
• Mesoscopic stresses up to Δ50 MPa were observed, influenced by the extent of interdendritic segregation.
• Carbides and inclusions in low-alloyed steel were ranked by their potential for residual stress formation.

Conclusions:

• This scale-bridging study offers a comprehensive overview of residual stress magnitude and evolution in low-alloyed steels across multiple length scales.
• The findings can serve as valuable input for the design and development of advanced steel materials.
• The research highlights the critical role of heat treatment and microstructural features in determining residual stress states.