Duplex Stainless Steel Wire Composition for Phase-Balanced 3D Printing
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Solution Overview
Problem
Additive manufacturing using duplex stainless steel wires faces challenges in achieving a well-balanced austenite and ferrite phase ratio, leading to excessive austenite structures and reduced pitting corrosion resistance, with existing methods requiring high-temperature heat treatments that are industrially impractical and prone to thermal stress.
Innovation Solution
An additive manufacturing wire with a specific composition (0% < Si ≤ 2.0%, 0% < Mn ≤ 6.0%, 3.0% ≤ Ni ≤ 15.0%, 20.0% ≤ Cr ≤ 30.0%, 1.0% ≤ Mo ≤ 5.0%, 0% < N ≤ 0.50%, with a balanced content of Fe and unavoidable impurities, and optional elements like Cu, Co, W, Al, Ti, Nb, and Mg, is used, along with a controlled cooling rate between 10°C/s and 140°C/s, and a heat treatment between 800°C and 1,200°C to achieve a ferrite content of 30% to 70% and optimize pitting corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If duplex stainless steel wire is used for additive manufacturing, then mechanical strength is improved, but pitting corrosion resistance deteriorates due to excessive austenite phase formation
Solution Approach 1:
The invention changes the compositional parameters of the stainless steel wire by precisely controlling the content of alloying elements (Ni: 8-15%, Cr: 18-25%, Mn: 2-6%, Mo: 2-4%, N: 0.05-0.50%) to adjust the phase transformation characteristics during additive manufacturing, thereby achieving a balanced austenite-ferrite phase ratio that simultaneously provides high strength and excellent pitting corrosion resistance
Solution Approach 2:
The invention creates a composite microstructure at the phase level by maintaining a specific ratio of austenite and ferrite phases in the solidified structure. This dual-phase composite structure combines the high strength of austenite with the excellent corrosion resistance of ferrite, resolving the contradiction between mechanical strength and pitting corrosion resistance
2Reliability
If heat treatment at 1,350°C or higher is applied to adjust phase ratio, then pitting corrosion resistance is improved, but thermal stress and industrial practicality worsen
Solution Approach 1:
The invention performs preliminary action by optimizing the chemical composition of the wire material before the additive manufacturing process. The pre-designed composition (particularly the balanced Ni-Cr-Mn-Mo-N system) ensures that the desired austenite-ferrite phase ratio is achieved during the normal cooling process of additive manufacturing, eliminating the need for subsequent high-temperature heat treatment to adjust phases
Solution Approach 2:
The invention changes the approach from post-processing parameter adjustment (high-temperature heat treatment) to pre-processing parameter optimization (wire composition design). By carefully selecting and controlling the content of alloying elements, the phase transformation characteristics are modified to achieve the desired microstructure during the additive manufacturing process itself, avoiding thermal stress
3Productivity
If additive manufacturing process is used, then manufacturing efficiency is improved, but phase ratio control deteriorates due to thermal history influence
Solution Approach 1:
The invention changes the material parameters (chemical composition) to compensate for the thermal history effects inherent in additive manufacturing. The optimized composition (Ni: 8-15%, Cr: 18-25%, Mn: 2-6%, Mo: 2-4%, N: 0.05-0.50%) is designed to achieve stable austenite-ferrite phase transformation under the rapid heating and cooling conditions of additive manufacturing, ensuring consistent phase ratio control despite the dynamic thermal environment
Solution Approach 2:
The invention enables the material to self-adjust its phase structure during the additive manufacturing process. The carefully designed composition allows the steel to automatically form the desired dual-phase microstructure through its own phase transformation characteristics during cooling, without requiring external intervention or post-processing to correct phase ratio deviations caused by thermal history
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 approach allows for the stable generation of a duplex stainless steel with a balanced austenite and ferrite phase ratio, enhancing pitting corrosion resistance and mechanical strength while avoiding excessive austenite formation and reducing thermal stress, thus achieving high-quality additively manufactured objects with improved properties.
Implementation Method 1
a phase ratio between an austenite phase and a ferrite phase is changed under the influence of thermal history such as heating and cooling
Implementation Method 2
under the influence of thermal history such as heating and cooling
Data Source
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AI summary
The present invention relates to an additive manufacturing wire, containing, in terms of % by mass, 0% < Si ≤ 2.0%, 0% < Mn ≤ 6.0%, 3.0% ≤ Ni ≤ 15.0%, 20.0% ≤ Cr ≤ 30.0%, 1.0% ≤ Mo ≤ 5.0%, 0% < N ≤ 0.50%, with a balance being Fe and unavoidable impurities, in which C ≤ 0.10% is satisfied, and 27 < A < 67 is satisfied, when Creq is defined as Cr + Mo + 1.5Si + 0.5(Nb+W) + 2(Ti+Al), Nieq is defined as Ni + 30C + 20N + 0.5(Mn+Cu+Co), and A is defined as -16.2 + 6.3Creq - 9.3Nieq, here, in the definition of Creq and Nieq, each element symbol indicates a content of the each element in units of % by mass.