Partially Diffusion-Alloyed Steel Powder with Molybdenum
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Solution Overview
Problem
Conventional alloyed steel powders for powder metallurgy lack excellent fluidity, formability, and compressibility while avoiding the high costs and oxidation issues associated with Ni, Cr, and Si, and often require additional manufacturing steps or special atmosphere control.
Innovation Solution
A partially diffusion-alloyed steel powder with Mo adhered to an iron-based powder, within specific Mo content and particle size ranges, to enhance sintering diffusion and stability, eliminating the need for Ni, Cr, and Si, and avoiding additional manufacturing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Cr or Si is added to alloyed steel powder to reduce Ni content and lower cost, then alloy cost is reduced, but the powder oxidizes under RX gas atmosphere during sintering, requiring high-level atmosphere control which increases manufacturing cost
Solution Approach 1:
The patent replaces expensive Ni with cheaper Mo, Cr, Si, or Cu alloying elements. Specifically, it uses Mo-based alloyed steel powder where Mo serves as a cost-effective alternative to Ni, achieving the desired quench hardenability at lower cost while avoiding the oxidation problems of Cr and Si
Solution Approach 2:
The patent eliminates the need for inert atmosphere control by selecting Mo as the alloying element. Mo does not oxidize under RX gas atmosphere like Cr and Si do, thereby removing the requirement for high-level atmosphere control during sintering and simplifying the manufacturing process
2Reliability
If Mo is added to improve quench hardenability and avoid oxidation issues, then compressibility and formability are improved, but the powder requires diffusion adhesion process which may increase manufacturing complexity
Solution Approach 1:
The patent applies diffusion adhesion of Mo to the surface of iron-based powder particles before sintering. This preliminary alloying action ensures that Mo is distributed on the particle surfaces, providing excellent quench hardenability and compressibility while maintaining a relatively simple manufacturing process using existing powder metallurgy techniques
3Ease of operation
If conventional alloying elements are used to ensure excellent fluidity and formability, then powder workability is improved, but additional manufacturing steps or special atmosphere control are required which increase production cost
Solution Approach 1:
The patent optimizes the composition parameters by using Mo-based alloying instead of Cr or Si, and controls the Mo content within specific ranges (0.05-1.0 mass% in the iron-based powder, with additional Mo powder added). This parameter optimization achieves excellent fluidity and formability while maintaining compatibility with standard powder metallurgy processes without requiring additional steps or special atmosphere control
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 solution achieves excellent fluidity, formability, and compressibility without Ni, Cr, and Si, reducing manufacturing costs and eliminating the need for special atmosphere control, while maintaining high quench hardenability and mechanical properties.
Implementation Method 1
a partially diffusion-alloyed steel powder comprising an iron-based powder and Mo diffusionally adhered to a surface of the iron-based powder
Data Source
AI summary
Disclosed is a partially diffusion-alloyed steel powder having excellent fluidity, formability, and compressibility without containing Ni, Cr, and Si. A partially diffusion-alloyed steel powder having excellent fluidity, formability, and compressibility that includes an iron-based powder and Mo diffusionally adhered to a surface of the iron-based powder, in which Mo content is 0.2 mass% to 2.0 mass%, a weight-based median diameter D50 is 40 µm or more, and among particles contained in the partially diffusion-alloyed steel powder, those particles having an equivalent circular diameter of 50 µm to 200 µm have a number average of solidity of 0.70 to 0.86, the solidity being defined as (particle cross-sectional area/envelope-inside area).