Clad Billet Interference Fit for Uniform Metallurgical Bonding
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Solution Overview
Problem
Conventional methods for producing clad billets with a metallurgical bond between carbon or low-alloy steel and corrosion-resistant alloys suffer from variability in bonding reliability, non-uniform cladding thickness, and porosity, leading to inadequate corrosion resistance in applications prone to chloride and marine environments.
Innovation Solution
A method involving heating a corrosion-resistant alloy cylinder, inserting a carbon or low-alloy steel material to create an interference fit, and extruding the composite billet assembly to form a 100% metallurgically bonded clad billet, which can be further processed into various clad products, ensuring a uniform and reliable bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wrapping and bonding methods are used to create metallurgically bonded clad bar, then corrosion resistance is improved, but bonding reliability becomes variable and inconsistent
Solution Approach 1:
The patent changes the bonding mechanism from mechanical wrapping to metallurgical bonding through controlled oxidation. By adjusting parameters such as oxygen potential, temperature, and time during the bonding process, consistent metallurgical bonds are achieved throughout the entire interface between the carbon steel core and stainless steel cladding, eliminating variability in bonding reliability and ensuring uniform cladding thickness.
2Object-affected harmful factors
If tightly wrapped sheathing is used to minimize gap between materials, then bonding surfaces are protected from oxidation, but protective mechanism cannot penetrate deep into long sheathing lengths
Solution Approach 1:
The patent extracts oxygen from the bonding interface by creating a controlled low-oxygen potential environment during the bonding process. This allows metallurgical bonding to occur throughout the entire interface even in long sheathing lengths, as the oxygen is removed rather than relying on protective mechanisms to penetrate and protect deep into the sheathing.
Solution Approach 2:
The patent introduces a controlled atmosphere or chemical environment as an intermediary that facilitates metallurgical bonding by managing oxygen potential. This intermediary mechanism enables consistent bonding throughout the entire interface area, regardless of sheathing length, by controlling the chemical environment rather than relying on physical barrier penetration.
3Reliability
If solid corrosion resistant alloy bars are used, then corrosion resistance is maximized, but cost increases significantly
Solution Approach 1:
The patent applies local quality by providing corrosion resistance only where needed - on the outer surface of the bar that contacts the corrosive environment. The carbon steel core provides mechanical strength while the stainless steel cladding provides corrosion resistance, creating a cost-effective composite structure with optimized material distribution rather than using expensive solid stainless steel throughout.
Solution Approach 2:
The patent creates a composite material structure combining carbon steel and stainless steel through metallurgical bonding. This composite clad bar leverages the advantages of both materials - the strength and cost-effectiveness of carbon steel in the core, and the corrosion resistance of stainless steel on the surface - achieving optimal performance at reduced cost compared to solid stainless steel bars.
4Quantity of substance
If corrosion resistant coatings are applied to carbon steel bars, then cost is reduced, but porosity in coating reduces corrosion protection effectiveness
Solution Approach 1:
The patent replaces the mechanical coating system with a metallurgical bonding system. Instead of applying a physical coating that can have porosity and adhesion issues, the stainless steel is metallurgically bonded to the carbon steel core, creating an integral, pore-free structure where the corrosion-resistant alloy becomes part of the material itself rather than a separate layer that can fail.
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 solution achieves a consistent, 100% metallurgical bond between the carbon or low-alloy steel and the corrosion-resistant alloy, providing enhanced corrosion resistance and durability in corrosive environments while maintaining cost-effectiveness.
Implementation Method 1
heating a corrosion-resistant alloy cylinder, the corrosion-resistant alloy cylinder including a hollow interior, an inner diameter, and an outer diameter
Implementation Method 2
cooling the heated corrosion-resistant alloy cylinder to contract at least the inner diameter of the corrosion-resistant alloy cylinder so that the inner diameter shrinks onto the outer surface of the solid carbon or low-alloy steel material creating an interference fit
Implementation Method 3
extruding the composite billet assembly to reduce the size of the composite billet assembly by reducing a thickness of each of the corrosion-resistant alloy cylinder and the solid carbon or low-alloy steel material and form the clad billet having a metallurgical bond between the solid carbon or low-alloy steel material and the corrosion-resistant alloy cylinder
Data Source
AI summary
A method of producing a clad billet includes heating a corrosion resistant alloy (CRA) cylinder having a hollow interior to expand its inner diameter; inserting a solid carbon or low-alloy steel (CS) material into the hollow interior of the heated (CRA) cylinder so that an outer surface of the (CS) material faces the inner diameter of the (CRA) cylinder; cooling the (CRA) cylinder to contract and shrink the inner diameter of the (CRA) cylinder onto the outer surface of the (CS) material creating an interference fit at an interface with the outer surface, resulting in a composite billet assembly; and hot extruding the composite billet assembly to reduce its size and form the clad billet having a metallurgical bond between the (CS) material and the (CRA) cylinder. The clad billet can be hot-rolled to form metallurgically-bonded clad bar, or can be cold pilgered/cold drawn to form a metallurgically-bonded clad pipe.