Fe-Based Alloy Composition for Additive Manufacturing Deformation Control

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Solution Overview

Problem

Current metal powders for additive manufacturing, such as SKD61 and maraging steel, face issues with high deformation during manufacturing, high as-manufactured hardness leading to low processing efficiency, and high costs due to excessive content of expensive alloying elements like Ni, Co, and Mo, which affect dimensional accuracy and production costs.

Innovation Solution

A Fe-based alloy with specific composition ranges for elements like C, Si, Mn, Ni, Cr, and N, optimized to balance hardness, machinability, and thermal properties, along with a metal powder having an average composition equivalent to this alloy, to minimize deformation and processing costs while maintaining high processing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal powders such as SKD61 and maraging steel are used for additive manufacturing, then high temperature strength and toughness are achieved, but high deformation occurs during manufacturing and as-manufactured hardness is high leading to low processing efficiency

Engineering Contradiction:
Improvetemperature strengthVSAvoiddimensional accuracy
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention changes the compositional parameters by strictly limiting C content to 0.03 mass% or less and controlling the balance of alloying elements, which fundamentally alters the material's hardening behavior and as-manufactured properties to reduce deformation while maintaining strength

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite microstructure consisting of martensite, retained austenite, and carbides through controlled composition and heat treatment, achieving a balance between strength, toughness, and reduced as-manufactured hardness for better processing efficiency

Inventive Principle:
Principle #40Composite materials

2Strength

If high-alloy steel powders containing Si, Cr, Ni, and Co are used, then high temperature strength is achieved, but thermal conductivity decreases due to dissolution of these elements in the matrix

Engineering Contradiction:
Improvetemperature strengthVSAvoidthermal conductivity
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The invention changes the compositional parameters by strictly limiting C content to 0.03 mass% or less and optimizing alloying element contents, which prevents excessive formation of carbides and maintains better thermal conductivity while achieving required strength through controlled martensitic transformation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces expensive alloying elements (Ni, Co, Mo) with more economical alternatives while achieving comparable or superior performance through optimized composition and heat treatment, reducing production cost without sacrificing thermal properties

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Strength

If maraging steel containing Ti is used for additive manufacturing, then toughness is improved, but Ti segregation occurs linearly during manufacturing reducing toughness

Engineering Contradiction:
ImprovetoughnessVSAvoidcompositional homogeneity
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The invention changes the compositional parameters by strictly limiting C content to 0.03 mass% or less and controlling alloying element contents, which prevents excessive carbide formation and promotes more uniform distribution of alloying elements during solidification, reducing segregation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention ensures compositional homogeneity throughout the additively manufactured part by optimizing material composition and processing parameters, preventing local segregation and ensuring uniform properties throughout the component

Inventive Principle:
Principle #3Local quality

4Strength

If metal powders with high as-manufactured hardness are used, then strength is achieved, but processing efficiency in as-manufactured state becomes low due to high cutting tool wear

Engineering Contradiction:
Improveas-manufactured hardnessVSAvoidprocessing efficiency
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The invention performs preliminary softening through controlled composition (low C content) and optional intermediate annealing before final heat treatment, allowing efficient machining or processing in the as-manufactured state, followed by hardening to achieve final strength requirements

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention creates a dynamic material system where the microstructure can be adjusted between soft (for processing) and hard (for final performance) states through controlled composition and heat treatment timing, optimizing both processing efficiency and final strength

Inventive Principle:
Principle #15Dynamics

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 Fe-based alloy and metal powder combination reduces deformation and processing costs by optimizing the composition to achieve low distortion, moderate hardness, and efficient processing, while maintaining low content of expensive alloying elements, thus improving the production efficiency and cost-effectiveness in additive manufacturing.

Implementation Method 1

a method of repeating a step of forming a thin powder layer made of a metal powder and a step of locally melting and solidifying the powder layer by irradiation with an energy beam such as a laser beam

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

locally melting and solidifying the powder layer by irradiation with an energy beam

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

locally melting and solidifying the powder layer

Methodology Applied
Scientific EffectSolidification: Freezing

Data Source

PatentEP4180549B1Fe-based alloy for melt-solidification-shaping and metal powder
Publication Date: 2024.07.24 DAIDO STEEL CO LTD
  • EP4180549B1 patent drawingFigure 1~2
  • EP4180549B1 patent drawingFigure 3
  • EP4180549B1 patent drawing

AI summary

The present invention relates to a Fe-based alloy for melt-solidification-shaping containing : 0.05 mass% ≤ C ≤ 0.25 mass%, 0.01 mass% < Si ≤ 2.0 mass%, 0.05 mass% ≤ Mn ≤ 2.5 mass%, 2.5 mass% ≤ Ni ≤ 9.0 mass%, 0.1 mass% ≤ Cr ≤ 8.0 mass%, and 0.005 mass% ≤ N ≤ 0.200 mass%, with the balance being Fe and unavoidable impurities, and satisfying: 11.5 < 15C+Mn+0.5Cr+Ni < 20.