Hot Rolled Coil for SEW Petroleum Casing
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Solution Overview
Problem
Current methods for producing high collapse-resistant SEW petroleum casings result in high alloy costs and difficulties with pipe welding due to low yield strength in hot rolled coils, which affects oil drilling efficiency and cost.
Innovation Solution
A continuous hot rolled coil with specific chemical compositions (0.22-0.32% C, 0.10-0.30% Si, 1.10-1.40% Mn, 0.30-0.60% Cr, P ≤0.020%, S ≤0.010%, 0.008-0.019% Ti, and inevitable impurities) is produced through a process involving continuous casting and rolling with controlled temperature and deformation, reducing expensive alloy element usage and improving mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high amounts of expensive alloy elements (Nb, V, Cr) are added to enhance strength, then the yield strength and tensile strength of petroleum casing are improved, but the alloy cost increases significantly
Solution Approach 1:
The patent optimizes the chemical composition parameters by precisely controlling the content ranges of C (0.24-0.30%), Si (0.10-0.30%), Mn (1.20-1.40%), Cr (0.30-0.60%), and Ti (0.008-0.019%). This parameter optimization achieves the required strength properties while minimizing expensive alloy additions, directly resolving the contradiction between strength enhancement and cost reduction
Solution Approach 2:
The patent creates a composite microstructure consisting of martensite, bainite, and retained austenite phases through controlled rolling and heat treatment processes. This multi-phase composite structure provides synergistic effects where martensite contributes strength, bainite provides toughness, and retained austenite enhances ductility, achieving high strength without excessive alloying
2Strength
If the yield strength of hot rolled coil is increased to meet high collapse-resistant requirements, then the collapse resistance of petroleum casing is improved, but the welding performance deteriorates due to excessive strength making welding difficult
Solution Approach 1:
The patent performs controlled rolling and heat treatment processes before final pipe formation to achieve the desired microstructure and strength properties in the coil form. This preliminary action ensures that the material has optimal welding characteristics in the as-rolled state, while the final pipe strength is achieved through subsequent heat treatment after welding, thus resolving the contradiction between collapse resistance and welding performance
Solution Approach 2:
The patent applies different processing conditions to different stages of production: the hot rolled coil is processed to have lower strength (340-360 MPa yield strength) for ease of welding, while the final pipe undergoes quenching and tempering to achieve high strength (840-910 MPa yield strength) for collapse resistance. This local quality approach allows each stage to have properties optimized for its specific function
3Strength
If conventional seamless pipes are used for high collapse-resistant casing, then the strength grade can be achieved, but the quality and benefit of oil drilling are affected due to large wall thickness deviation, uneven performance, and fast casing damage
Solution Approach 1:
The patent replaces the conventional seamless pipe manufacturing process with a welded pipe process using controlled rolling technology. This substitution allows for better control of wall thickness uniformity through the continuous rolling process, eliminates the perforation cracking issues associated with seamless pipes, and enables more consistent mechanical properties through controlled microstructure development in the welded joints
Solution Approach 2:
The patent implements controlled rolling with specific deformation parameters (≥18% reduction per pass in rough rolling, ≥20% in finish rolling) and temperature control (950-1050°C entry temperature, 850-950°C finish rolling temperature) to achieve uniform microstructure and properties throughout the pipe, providing feedback control over the manufacturing process to ensure consistent quality
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 process achieves a significant reduction in production costs while enhancing the mechanical properties of the coils, ensuring excellent welding properties and increased strength for the quenched and tempered coils, with initial yield strengths of 840-910 MPa and tensile strengths of 940-1030 MPa.
Implementation Method 1
a continuous cast and rolled coil comprising the following chemical components
Implementation Method 2
continuous hot rolling production
Implementation Method 3
For the quenched and tempered continuous cast and rolled coil, the initial yield strength is 840 MPa-910 MPa and the initial tensile strength is 940 MPa-1030 MPa
Data Source
AI summary
The invention discloses a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing and a manufacturing method thereof, and belongs to the technical field of hot continuous rolling production. Provided is a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing with low alloy element cost and excellent initial welding property, and a manufacturing method thereof. The production cost of the hot continuous rolled coil is lowered by reducing expensive alloy elements such as Mo and V therein, and strictly controlling the content components of chemical elements such as Cr, Mn and Ti. According to the manufacturing method, a continuous cast slab is used as an initial billet and subjected to rough rolling by refined grains for 5-7 passes under the temperature-controlled heating condition to form an intermediate billet, and then the intermediate billet is subjected to finish rolling for at least 4 passes, then finally cooled and coiled to complete the production and processing of the continuous hot rolled coils, and achieve the purpose of controlling the initial yield strength and the initial tensile strength.