Maraging Steel Grain Refiners for Additive Manufacturing

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Solution Overview

Problem

Current maraging steel alloys face challenges in additive manufacturing due to anisotropic material properties and low fracture toughness resulting from columnar grain structures, limiting their strength and toughness.

Innovation Solution

Incorporating grain refiners into the maraging steel alloy during additive manufacturing to induce equiaxed microstructures, which reduces cracking tendencies and enhances material isotropy, thereby overcoming the limitations of columnar grain structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If additive manufacturing is used to produce maraging steel alloys, then manufacturing complexity is reduced and design freedom is improved, but the material develops columnar grain structures causing anisotropic properties and low fracture toughness

Engineering Contradiction:

Improveadditive manufacturing capabilityVSAvoidfracture toughness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent modifies the solidification parameters by introducing grain refiners (TiB2, CeO2, TiN, NbC) at specific concentrations (0.01-10% by volume) to change the grain structure from columnar to equiaxed, thereby altering the material's microstructural parameters to achieve isotropic properties while maintaining additive manufacturing capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Grain refiners are introduced as intermediary substances during additive manufacturing to mediate the solidification process. These refiners nucleate equiaxed grains and prevent columnar growth, acting as a bridge between the additive manufacturing process and the desired isotropic microstructure

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If conventional maraging steel alloys are processed via additive manufacturing, then production flexibility is improved, but cracking tendencies increase due to columnar grain structures

Engineering Contradiction:

Improveprocessing flexibilityVSAvoidcracking tendencies

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the microstructural parameters by incorporating grain refiners that promote equiaxed grain formation, which fundamentally alters the solidification behavior and reduces cracking tendencies while preserving processing flexibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system by dispersing grain refiner particles (TiB2, CeO2, TiN, NbC) within the maraging steel alloy matrix, forming a composite material that exhibits reduced cracking and improved toughness while maintaining the base alloy's mechanical properties

Inventive Principle:

Principle #40Composite materials

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 use of grain refiners enables the production of high-strength maraging steel alloys with improved isotropic material properties and reduced cracking, allowing for the additive manufacturing of previously difficult-to-process alloys with enhanced strength and toughness.

Implementation Method 1

Incorporating grain refiners into the maraging steel alloy during additive manufacturing to induce equiaxed microstructures

Methodology Applied

Scientific EffectNucleation: Nucleation

Data Source

PatentUS11608548B2Maraging steel alloy and methods of making the same

Publication Date: 2023.03.21 THE BOEING CO

AI summary

Provided are maraging steel alloys having improved microstructures. Some variations provide maraging steel alloys including a base maraging steel alloy, a grain refiner, and optionally, a strengthening element. The base maraging steel alloy is surface-functionalized with the grain refiner. Other variations provide a method of method of manufacturing maraging steel including mixing a base maraging steel alloy with a grain refiner resulting in a maraging steel mixture, melting the maraging steel mixture, and solidifying the maraging steel mixture forming an equiaxed microstructure.