Thick Flange Steel Forging for Pore Compression and Low-Temperature Toughness
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Solution Overview
Problem
Existing methods struggle to produce extremely thick steel materials for flanges with both high strength and low-temperature impact toughness, as they often result in residual pores and surface defects, particularly due to insufficient deformation of the material center and localized strain concentration during manufacturing processes.
Innovation Solution
A method involving specific alloy compositions and a multi-step forging process, including heating, upsetting, and normalizing heat treatment, to achieve a composite microstructure of pearlite and ferrite with controlled grain size and porosity, along with fine precipitates, ensuring excellent strength and toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of steel material is increased to meet large-scale energy production requirements, then the strength and durability are improved, but the material deteriorates due to defects such as inclusions, segregation, and residual pores
Solution Approach 1:
The patent applies parameter changes by controlling the chemical composition parameters (C: 0.05-0.20%, Si: 0.10-0.50%, Mn: 1.00-2.00%, etc.) and processing parameters (heating temperature 1100-1300°C, forging ratios, cooling rates) to achieve the desired balance between strength and internal soundness in extremely thick steel materials
Solution Approach 2:
The patent applies preliminary action by performing multiple forging operations (first upsetting, bloom forging, round forging, second upsetting, third upsetting, ring forging) before final product formation to progressively compress and eliminate residual pores and defects in the center of the thick material
2Reliability
If high reduction ratio is applied in rolling process to improve internal soundness, then the concentration of impurities is reduced, but it is technically difficult to apply high strain to the center where residual pores exist in extremely thick materials
Solution Approach 1:
The patent applies segmentation by dividing the deformation process into multiple discrete forging operations (first upsetting, bloom forging, round forging, second upsetting, third upsetting, ring forging) with specific forging ratios, allowing progressive compression of the material center to eliminate residual pores without exceeding equipment capabilities in a single step
Solution Approach 2:
The patent transitions from a single-dimension rolling process to multi-dimensional forging operations that can apply strain more effectively to the center of extremely thick materials by changing the deformation geometry and applying force from multiple directions
3Reliability
If cumulative reduction amount is increased to compress central pores, then the internal soundness is improved, but surface defects may occur due to localized strain concentration
Solution Approach 1:
The patent applies local quality by optimizing the forging process to achieve different deformation characteristics in different regions of the material - the center region receives progressive compression to eliminate pores, while the surface region maintains controlled strain to prevent defect formation, with each forging operation carefully controlled to balance these competing requirements
4Strength
If the material thickness is increased to 200mm or more for high-strength applications, then the durability is improved, but the deformation of the center of the material is not large, making it difficult to compress residual pores
Solution Approach 1:
The patent applies preliminary action by performing a series of forging operations with progressively increasing deformation before final product formation, allowing the center of the thick material to be gradually compressed and pores to be eliminated before the material is finished, ensuring both the required thickness and internal soundness
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 method effectively compresses central pores and improves internal soundness, resulting in a steel material with enhanced low-temperature impact toughness and strength, minimizing surface cracks and defects.
Implementation Method 1
a first upsetting with a forging ratio of 1.3 to 2.4; bloom forging with a forging ratio of 1.5 to 2.0... round forging with a forging ratio of 1.65 to 2.25, and then performing a second upsetting with a forging ratio of 1.3 to 2.3; performing a third upsetting with a forging ratio of 2.0 to 2.8... ring forging with a forging ratio of 1.0 to 1.6
Implementation Method 2
heating the manufactured slab to a temperature within a range of 1100 to 1300° C.... reheating the bloom forged material to a temperature within a range of 1100 to 1300° C.... reheating the hole-processed material to a temperature within a range of 1100 to 1300° C.
Implementation Method 3
performing a normalizing heat treatment by heating the ring-forged material to a temperature within a range of 820 to 930° C. based on a temperature measurement standard of a central portion thereof and maintaining the temperature for 5 to 600 minutes and then performing air cooling to room temperature
Data Source
AI summary
The present disclosure relates to an extremely thick steel material for a flange having excellent strength and low-temperature impact toughness, and a method of manufacturing the same.