Thermomechanical Processing for Heavy Plate Toughness
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Solution Overview
Problem
Conventional thermomechanical treatment processes for heavy plates struggle to achieve high toughness values, particularly low-temperature toughness, as the advantages seen in thin sheets are not replicable in thicker plates due to limitations in mechanical forming and available forming degrees, leading to reduced toughness and the need for expensive and time-consuming chemical compositions and heat treatments.
Innovation Solution
A thermomechanical treatment method involving accelerated cooling of heavy plates to a temperature below Ar3 followed by inductive heating above Ac3, combined with thermomechanical or recrystallization-controlled rolling, to achieve grain refinement and improved toughness, allowing for higher-quality toughness properties in thick plates without significant strength reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional thermomechanical treatment processes are used for heavy plates, then the forming process is simplified, but the toughness values particularly low-temperature toughness are reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling temperature ranges during rolling operations. The heavy plate is heated to specific temperature ranges (Ac3 to Ac1 for partial forming, Ar3 to Ar1 for final forming) and cooled at controlled rates, transforming the microstructure to achieve high toughness without complex additional processes
Solution Approach 2:
The patent utilizes phase transitions of steel during thermomechanical processing. By heating above Ac3 to form austenite, then controlling cooling through Ac1 and Ar3 to Ar1 temperature ranges, the material undergoes phase transformations that refine grain structure and improve toughness properties
2Manufacturing precision
If the heavy plate is cooled in an accelerated manner after partial forming, then grain refinement is improved, but the time for the treatment process increases
Solution Approach 1:
The patent maintains continuous useful action by integrating accelerated cooling directly into the rolling process sequence. The heavy plate transitions continuously from partial forming to accelerated cooling to final forming without intermediate waiting periods, achieving grain refinement while minimizing total process time
3Speed
If inductive heating is used to heat the heavy plate above Ac3, then the heating speed is increased, but the equipment complexity increases
Solution Approach 1:
The patent replaces conventional thermal heating systems with inductive heating technology. Electromagnetic fields induce eddy currents within the heavy plate, generating heat internally and rapidly achieving the required temperature above Ac3, significantly reducing heating time compared to traditional external heating methods
4Shape
If the heavy plate is subjected to partial and final forming by rolling, then the shape control is improved, but the achievable toughness values are reduced due to mechanical forming limits
Solution Approach 1:
The patent overcomes mechanical forming limits by changing the temperature parameter throughout the process. By performing partial forming at high temperature (Ac3 to Ac1) where the material is more ductile, and final forming at controlled temperature (Ar3 to Ar1), the process achieves both excellent shape control and high toughness values that would be unattainable at ambient temperature
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
This method significantly enhances low-temperature toughness in heavy plates, making them suitable for applications like oil and gas pipelines, while being cost-effective and easy to integrate into existing processes, with improved throughput and material properties.
Implementation Method 1
the heavy plate heated to a temperature above Ac3 for partial forming is cooled in an accelerated manner after its final forming
Implementation Method 2
the heavy plate heated to a temperature above Ac3 for partial forming is cooled in an accelerated manner after its final forming
Data Source
Figure 1
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Figure 2B
AI summary
The invention relates to a thermomechanical treatment method for producing thick plate (1) from a starting material in order to increase the toughness, in particular the low-temperature toughness, of the thick plate (1), wherein the thick plate (1) is heated, is partially and finally shaped by rolling, and is cooled down at an accelerated rate compared to a cool-down at ambient temperature, wherein the thick plate (1), which is heated to above the Ac3 temperature for partial shaping, is cooled down at an accelerated rate after the thick plate has been finally shaped. In order to achieve advantageous properties of the thick plate, the thick plate (1) is cooled down to below the Ar3 temperature at an accelerated rate between the partial shaping and the final shaping and then is inductively heated to above the Ac3 temperature.