Aluminium Extrusion Die Material with SPS-Sintered Nanostructure
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Solution Overview
Problem
Existing methods for producing extrusion dies for aluminum profiles face challenges in achieving sufficient hardness, tempering resistance, and adhesion properties for vapor-deposited layers, which affects die lifetime and performance.
Innovation Solution
A method involving the use of a steel powder with specific composition and particle size, combined with grain growth inhibitors, followed by milling to achieve a certain crystallite size, mixing, sintering using discharge plasma sintering (SPS), and subsequent machining and coating to produce an extrusion die with enhanced mechanical and tribological features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional manufacturing methods (HIP, hot rolling) are used to produce extrusion dies, then the production process is established and reproducible, but the die material does not achieve sufficient hardness, tempering resistance, and adhesion properties for vapor-deposited layers
Solution Approach 1:
The patent changes the fundamental manufacturing parameters by using powder metallurgy with SPS sintering instead of traditional HIP and hot rolling. This involves changing the starting material form (powder vs. ingot), the sintering temperature (950-1200°C vs. higher temperatures), and the process sequence, thereby achieving superior material properties while maintaining manufacturing feasibility
Solution Approach 2:
The patent creates a composite microstructure by combining steel powder with grain growth inhibitors (carbides, oxides, nitrides) in controlled amounts (0.05-2.5 wt%). This composite approach at the microstructural level provides both the required mechanical strength and grain boundary control for improved tempering resistance and adhesion properties
2Strength
If the steel powder is milled to achieve a mean crystallite size of 20-100 nm, then the material achieves improved hardness and tempering resistance, but the milling process time and energy consumption increase
Solution Approach 1:
The patent employs periodic pulsed electric current in the SPS sintering process, which enables rapid heating and cooling cycles. This periodic action allows achieving fine crystallite size (20-100 nm) through controlled grain growth during brief high-temperature pulses, reducing the overall processing time compared to continuous heating methods
Solution Approach 2:
The patent performs preliminary high-energy milling to reduce the steel powder to fine crystallites (20-100 nm) before sintering. This preliminary size reduction creates a microstructure that is more responsive to subsequent SPS processing, allowing the desired fine-grained structure to be achieved with shorter sintering times and lower temperatures
3Manufacturing precision
If discharge plasma sintering (SPS) is used at temperatures of 950-1200°C, then the green body achieves sufficient density and mechanical properties, but the equipment complexity and energy consumption increase
Solution Approach 1:
The patent replaces traditional mechanical heating and pressure application systems with a plasma-based electric field system. The pulsed electric current generates plasma that directly heats the compact to sintering temperature while simultaneously applying pressure, eliminating the need for separate heating elements and pressure transmission mechanisms, thereby reducing overall equipment complexity
4Reliability
If the carbon content of the steel powder is reduced to lower than 0.8 wt.% (or lower than 0.5 wt.% or lower than 0.1 wt.%), then the material achieves improved adhesion properties for coating layers, but the inherent strength and hardness of the steel matrix decrease
Solution Approach 1:
The patent applies local quality by creating a dual-nature material structure: the steel matrix has controlled low carbon content ( <0.8 wt.%, or <0.5 wt.%, or <0.1 wt.%) for optimal adhesion, while localized regions contain grain growth inhibitors (carbides, oxides, nitrides) that provide strength reinforcement. This spatial differentiation of composition allows simultaneous optimization of adhesion and strength
Solution Approach 2:
The patent creates a composite steel matrix by combining low-carbon steel powder with grain growth inhibitors (0.05-2.5 wt%). The low-carbon steel provides excellent adhesion properties for vapor-deposited coating layers, while the dispersed carbide/oxide/nitride particles provide strength reinforcement and grain boundary strengthening, achieving both adhesion and strength requirements
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 results in an extrusion die with improved hardness, tempering resistance, and adhesion properties, leading to increased die lifetime, better hot strength and creep resistance, and enhanced surface-tribological performance.
Implementation Method 1
sintering the green body by discharge plasma sintering (SPS), at a temperature in the range of 950-1200° C.
Implementation Method 2
milling at least the steel powder to a mean crystallite size of 20-100 nm
Implementation Method 3
The coating layer may be deposited by chemical vapor deposition, CVD, on the surface of the shaped extrusion die.
Implementation Method 4
The coated extrusion die may be subjected to a final heat treatment step, age-hardening, to obtain the final hardness of the material.
Data Source
AI summary
A method of producing a die or a die material for extrusion of aluminum profiles, comprising the steps of: providing a first powder, which is a steel powder having the following composition in weight %: C<1.2; Co 6.0-15; Mo 5.0-11.0; Mn 0-1.5; Si 0-1.25; Cr 2-8; Ni 0.5-6.0; P<0.1; balance Fe and unavoidable impurities, said steel powder having a mean particle size of 5-100 um, providing a second powder containing one or more grain growth inhibitors selected among the group comprising carbides, oxides and nitrides, milling at least the steel powder to a mean crystallite size of 20-100 nm, mixing the first and second powders to a powder mixture, wherein the content of the second powder in the powder mixture is in the range of 0.05-2.5 weight %, forming a green body of the powder mixture, and sintering the green body by discharge plasma sintering (SPS), at a temperature in the range of 950-1200° C.