Continuous Casting Mold Copper Plate Filling to Prevent Spalling
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Solution Overview
Problem
Existing continuous casting molds face issues with stress generation and cracking due to thermal strain differences between metals of low thermal conductivity and copper, especially at increased casting velocities, leading to spalling and reduced mold life.
Innovation Solution
A multi-layered built-up filling laminate is formed using a laser-beam buildup method, with nickel or nickel-based alloy layers stacked in concave portions of the mold copper plate, enhancing adhesion strength and heat resistance through controlled diffusion and composition gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal of low thermal conductivity is filled in concave portions of the mold surface, then stress generated on the mold surface is dispersed and cracking is less likely to occur, but thermal strain difference between the filled metal and copper plate generates large stress on the boundary surface leading to spalling and reduced mold life
Solution Approach 1:
The patent applies composite materials by creating a multi-layered filling laminate structure within the concave portions. The laminate consists of a base layer (first layer) made of nickel or nickel-based alloy that is directly bonded to the copper plate, and overlay layers (second layer and above) made of metals with low thermal conductivity such as silver, aluminum, or their alloys. This composite structure allows the base layer to provide strong adhesion to the copper plate while the overlay layers provide the desired low thermal conductivity for stress dispersion, thereby resolving the contradiction between preventing surface cracking and maintaining boundary surface strength.
Solution Approach 2:
The patent applies local quality by creating a composition gradient within the filling laminate. The base layer has different material composition than the overlay layers, with each layer having specific thermal conductivity properties tailored to its function. The base layer is designed for strong bonding and thermal matching with copper, while the overlay layers are designed for low thermal conductivity and stress dispersion. This local differentiation of material properties within the filling structure allows simultaneous achievement of strong adhesion and effective stress dispersion.
2Productivity
If casting speed is increased to improve productivity, then output increases, but heat accumulated in the filled metal increases causing excessive temperature rise and potential coating layer spalling
Solution Approach 1:
The multi-layered composite structure with the copper- bonded base layer provides improved thermal management. The base layer's thermal properties are optimized to conduct heat away from the overlay layers, preventing excessive temperature accumulation even at high casting speeds. This allows the mold to maintain structural integrity and prevent spalling while operating at higher productivity levels.
3Ease of manufacture
If a single-layer filling metal is used, then manufacturing is simpler, but adhesion strength between the filling metal and copper plate is insufficient leading to spalling
Solution Approach 1:
The patent applies preliminary action by pre-forming the base layer with optimized composition and thickness before applying the overlay layers. The base layer is prepared in advance to provide the necessary bonding interface with the copper plate, ensuring strong adhesion is established before the low thermal conductivity overlay layers are added. This sequential preparation ensures strong adhesion while maintaining manufacturing efficiency.
4Reliability
If the thickness of the filling metal layer is increased to improve heat resistance, then thermal insulation improves, but stress concentration and spalling risk increase due to excessive thermal resistance
Solution Approach 1:
The multi-layered composite structure allows optimization of each layer's thickness independently. The base layer thickness is optimized for adhesion and thermal management, while the overlay layers provide additional thermal insulation with controlled thickness to prevent excessive thermal resistance. This layered approach allows achieving sufficient heat resistance without the stress concentration and spalling risks associated with thick single-layer fillings.
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 increases adhesion strength and heat resistance, reducing stress and cracking, thereby improving mold durability and productivity in high-speed casting.
Implementation Method 1
radiating a laser beam while feeding nickel powder or nickel-based alloy powder to melt and solidify the powder
Implementation Method 2
by diffusion of copper from the mold copper plate by irradiating the nickel coating layer with a laser beam to melt the coating layer
Data Source
AI summary
Provided is a method for manufacturing a continuous casting mold, in which plural concave portions formed on an inner surface of a copper-made mold copper plate or a copper alloy-made mold copper plate used for continuously casting steel at least in a region including a meniscus position of molten steel in a casting process are filled with a metal having a thermal conductivity different from that of the mold copper plate, in which cracking and spalling are less likely to occur in the filling laminate. The filled metal is a filling laminate formed of two or more layers in such a manner that the layers are stacked on top of one another from a bottom of the concave portion to an open of the concave portion in a direction normal to an inner surface of the mold, in which each of a second layer and layers above the second layer is a nickel layer or a nickel-based alloy layer having a thickness of 0.2 mm to 2 mm formed by radiating a laser beam while feeding nickel powder or nickel-based alloy powder to a position irradiated with the laser beam to melt and solidify the nickel powder or the nickel-based alloy powder, and the second layer and the layers above the second layer form a multi-layered built-up filling laminate having a total thickness of 1 mm to 10 mm.