Ce-Containing S355J2 H-Beam Rolling for Uniform Steel Quality
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Solution Overview
Problem
Existing production processes for hot-rolled H-beams face challenges in incorporating rare earth elements, particularly in shaped billets, leading to issues like cracks and uneven quality, making it difficult to achieve high-performance and cost-effective steel production.
Innovation Solution
A production process for S355J2 hot-rolled H-beams using a cerium-iron alloy additive, involving controlled smelting, continuous casting, and rolling operations to produce a hot-rolled H-beam with specific chemical compositions and temperature controls, ensuring stability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shaped billet is used for continuous casting with rare earth elements, then the steel quality can be improved through inclusion modification, but the production process becomes complex and prone to defects like web cracks
Solution Approach 1:
The patent segments the production process by separating the rare earth addition step from the continuous casting process. Rare earth elements are added to the molten steel before casting, allowing inclusion modification to occur during subsequent rolling operations rather than during casting, thereby simplifying the casting process while maintaining steel quality improvement
Solution Approach 2:
The patent applies preliminary action by adding rare earth elements to the molten steel before the continuous casting process. This preliminary addition allows the rare earth to interact with inclusions during rolling, achieving inclusion modification without requiring complex modifications to the casting process itself
2Productivity
If a double-nozzle system is used for casting shaped billets, then the casting process can be completed, but liquid level fluctuations and nozzle clogging occur leading to web cracks
Solution Approach 1:
The patent extracts the rare earth addition from the casting nozzle system and performs it separately in the molten steel before casting. This eliminates the need for a double-nozzle system and its associated problems with liquid level fluctuations and clogging, while still achieving the desired inclusion modification through subsequent rolling processes
3Ease of manufacture
If a rectangular billet is used instead of shaped billet, then the production process is simplified and cost is reduced, but the ability to add rare earth during smelting is limited
Solution Approach 1:
The patent enables continuous addition of rare earth elements during the smelting process when using rectangular billets. This continuous addition approach maintains production simplicity while allowing sufficient rare earth to be incorporated into the steel, achieving both ease of manufacture and adequate rare earth content for inclusion modification
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 high-performance, low-cost, and consistent S355J2 hot-rolled H-beams with improved mechanical properties and metal utilization, reducing stress concentrations and enhancing impact toughness.
Implementation Method 1
the rare earth plays two main roles in steel: the first is to purify the molten steel and improve the quality of the steel by modifying inclusions with the rare earth
Implementation Method 2
a rectangular billet, after being heated, is rolled into an I-shaped billet in a blooming mill
Implementation Method 3
rolled into an I-shaped billet in a blooming mill, and then fed into a multi-stand universal mill for continuous hot rolling
Data Source
AI summary
Provided is a production process of an S355J2 hot rolled H-beam for a Ce-containing beam-column member, relating to the production of hot-rolled H-beams. The production process can ensure the performance of the hot-rolled H-beam with multiple classes from one steel grade, and achieve low cost, stability, uniformity, consistency, and narrow composition control of various elements. In the S355J2 hot-rolled H-beam for a Ce-containing beam-column member, a hot-rolled H-beam is prepared from the following compositions by mass fraction: 0.18%-0.20% of C, 0.25%-0.30% of Si, 1.22%-1.27% of Mn, less than or equal to 0.025% of P, less than or equal to 0.025% of S, 0.008%-0.011% of Nb, 0.008%-0.012% of V, 0.004%-0.008% of N, 0.0015%-0.0055% of Ce, less than or equal to 0.015% of Al, and the rest of Fe and inevitable impurities.