Seamless Stainless Steel Pipe Composition for Sour Corrosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing stainless steel pipes for oil country tubular goods lack sufficient corrosion resistance in severe environments containing CO2, Cl−, H2S, and acid, and do not meet the required high strength for deep oil fields and high temperatures.
Innovation Solution
A stainless steel seamless pipe composition comprising specific amounts of Cr, Mo, Ni, Cu, W, and Co, with a microstructure of martensitic, ferrite, and retained austenite phases, and a manufacturing process involving quenching and tempering to achieve a yield strength of 758 MPa or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If 13Cr martensitic stainless steel pipes are used for oil country tubular goods, then the pipes can be produced with high strength, but the corrosion resistance in severe high-temperature corrosive environments containing CO2, Cl−, and H2S is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters by specifying Cr: 16-18%, Mo: 2-3%, Cu: 1-3%, Ni: 3-5%, and other elements within defined ranges, along with controlling C, Si, Mn, P, S, Al, O, and N content. This parameter optimization resolves the contradiction by achieving both high strength and excellent corrosion resistance in severe environments including CO2, Cl−, and H2S exposure.
Solution Approach 2:
The patent creates a composite alloy system combining multiple elements (Cr, Mo, Cu, Ni, and others) in specific proportions to form a material with superior properties. This composite approach allows the steel pipe to simultaneously achieve high strength and enhanced corrosion resistance in harsh oil well environments.
2Strength
If the steel pipe composition is optimized for high strength, then the yield strength increases, but the corrosion resistance in acid environments deteriorates
Solution Approach 1:
The patent specifies precise parameter ranges including Cr: 16-18%, Mo: 2-3%, Cu: 1-3%, Ni: 3-5%, and controls C: 0.06% or less, Si: 1.0% or less, P: 0.05% or less, S: 0.005% or less, Al: 0.10% or less, N: 0.10% or less, O: 0.010% or less, W: 0.5-2.0%, and Co: 0.01-1.5%. These parameter optimizations ensure both high yield strength (758 MPa or more) and excellent acid-environment corrosion resistance.
3Strength
If the steel pipe is designed for high strength application, then the mechanical strength improves, but the corrosion resistance in CO2 and Cl− containing environments deteriorates
Solution Approach 1:
The patent optimizes composition parameters with Cr: 16-18%, Mo: 2-3%, Cu: 1-3%, Ni: 3-5%, and严格控制 C: 0.06% or less, Si: 1.0% or less, P: 0.05% or less, S: 0.005% or less. This parameter control achieves both high mechanical strength and superior resistance to CO2 and Cl− corrosion in high-temperature environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The pipe exhibits excellent corrosion resistance in corrosive environments, including carbon dioxide gas, sulfide stress cracking resistance, and acid-environment corrosion resistance, with a yield strength of 758 MPa or more.
Implementation Method 1
a method including: forming a seamless steel pipe of predetermined dimensions from a steel pipe material; quenching that heats the seamless steel pipe to a temperature ranging from 850 to 1,150° C., and cools the seamless steel pipe to a surface temperature of 50° C. or less at a cooling rate of air cooling or faster
Implementation Method 2
tempering that heats the quenched seamless steel pipe to a temperature of 500 to 650° C.
Implementation Method 3
the stainless steel seamless pipe having a microstructure containing at least 25% martensitic phase, at most 65% ferrite phase, and at most 40% retained austenite phase by volume
Implementation Method 4
the stainless steel seamless pipe having a microstructure containing at least 25% martensitic phase, at most 65% ferrite phase, and at most 40% retained austenite phase by volume
Implementation Method 5
the stainless steel seamless pipe having a microstructure containing at least 25% martensitic phase, at most 65% ferrite phase, and at most 40% retained austenite phase by volume
Data Source
AI summary
A stainless steel seamless pipe having high strength and excellent corrosion resistance. The stainless steel seamless pipe has a specified composition in which C, Si, Mn, Cr, Ni, Mo, Cu, and N satisfy a predetermined formula, a microstructure containing at least 25% martensitic phase, at most 65% ferrite phase, and at most 40% retained austenite phase by volume, and a yield strength of 758 MPa or more.