Carburization Resistant Alloy Composition for Furnace Components
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Solution Overview
Problem
Conventional techniques for enhancing metal dusting resistance, carburization resistance, and coking resistance in high-temperature metal materials require special heat treatment and surface treatment, leading to increased costs and labor, and lack effective scale restoration after the pre-oxidized scale or surface treatment layer exfoliates, while also compromising weldability, creep strength, and creep ductility.
Innovation Solution
A metal material composition with specific ranges of C, Si, Mn, P, Cr, Ni, Cu, Al, Ti, and O is developed, which forms a stable oxide scale and incorporates noble metal elements like Cu to restrain dissociative adsorption of carbon-containing gas molecules, improving metal dusting resistance, carburization resistance, and coking resistance, while optimizing weldability and creep ductility by controlling grain boundary segregation and precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat treatment and surface treatment are applied to enhance metal dusting resistance and carburization resistance, then corrosion resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent modifies the chemical composition parameters of the base metal material itself, specifying precise ranges for Cr (20-35%), Ni (35-60%), Si (0.5-2.0%), and other elements. By changing the material's intrinsic parameters rather than applying external treatments, the patent achieves improved corrosion resistance while avoiding the complexity of additional heat treatment or surface treatment processes
Solution Approach 2:
The patent enables the metal material to protect itself through its own composition. The specific alloying elements (particularly Cr and Ni) automatically form protective oxide films and resist carburization and metal dusting under service conditions without requiring external interventions. The material's own chemical composition provides the corrosion resistance function
2Reliability
If Cr and Ni content are increased to improve corrosion resistance, then metal dusting resistance is enhanced, but weldability deteriorates
Solution Approach 1:
The patent optimizes the Cr and Ni content within specific ranges (Cr: 20-35%, Ni: 35-60%) rather than using excessive amounts. This parameter optimization ensures sufficient corrosion and metal dusting resistance while limiting the negative impact on weldability. The balanced composition achieves the necessary performance without over-alloying
Solution Approach 2:
The patent introduces localized micro-alloying with small amounts of specific elements (Ti: 0.01-0.10%, Nb: 0.01-0.10%, V: 0.01-0.10%) that provide localized strengthening and carbide precipitation resistance. This allows the bulk material to maintain good weldability while specific local regions provide enhanced mechanical properties and corrosion resistance
3Reliability
If Si content is increased to improve carburization resistance, then oxide film formation is enhanced, but creep strength decreases
Solution Approach 1:
The patent precisely controls Si content within a narrow range (0.5-2.0%) to achieve the optimal balance between carburization resistance and creep strength. This parameter optimization ensures sufficient oxide film formation for protection while limiting Si's negative effect on high-temperature strength and creep resistance
4Strength
If C content is increased to improve high-temperature strength, then strength is enhanced, but metal dusting resistance decreases
Solution Approach 1:
The patent carefully controls C content within a specific range (0.03-0.10%) to achieve sufficient high-temperature strength through solid solution strengthening and controlled carbide precipitation, while limiting excessive carbon that would promote metal dusting. The balanced carbon level maintains both strength and resistance to carbon-related degradation
Solution Approach 2:
The patent creates a composite alloy system combining Fe, Cr, Ni, Si, and micro-alloying elements that work synergistically. The Cr and Ni form protective oxide films that prevent carbon ingress, while the Si enhances oxide film stability. This composite material approach achieves high-temperature strength and metal dusting resistance simultaneously through the combined effect of multiple elements rather than relying on high carbon content alone
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 metal material effectively restrains reactions with carburizing gases, enhancing metal dusting resistance, carburization resistance, and coking resistance, and improves weldability and creep ductility, ensuring durability and operation efficiency in high-temperature applications such as cracking furnaces and heat exchangers.
Implementation Method 1
elements such as Cr and Si, which have higher oxidation tendency than Fe or Ni or the like, are oxidized selectively, and a dense film of chromium oxide or silicon oxide or the like is formed
Implementation Method 2
the dissociative adsorption of the gas molecules consisting of C compounds is restrained on the metal surface
Implementation Method 3
the diffusion of element from the inside to the surface of metal material is insufficient
Data Source
AI summary
There is provided a carburization resistant metal material suitable as a raw material for cracking furnaces, reforming furnaces, heating furnaces, heat exchangers, etc. in petroleum and gas refining, chemical plants, and the like. This metal material consists of, by mass %, C: 0.03 to 0.075%, Si: 0.6 to 2.0%, Mn: 0.05 to 2.5%, P: 0.04% or less, S: 0.015% or less, Cr: higher than 16.0% and less than 20.0%, Ni: 20.0% or higher and less than 30.0%, Cu: 0.5 to 10.0%, Al: 0.15% or less, Ti: 0.15% or less, N: 0.005 to 0.20%, and O (oxygen): 0.02% or less, the balance being Fe and impurities. The metal material may further contain one kind or more kinds of Co, Mo, W, Ta, B, V, Zr, Nb, Hf, Mg, Ca, Y, La, Ce and Nd.