Iron Alloy Additive Manufacturing Temperature Control
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Solution Overview
Problem
Conventional iron alloy manufacturing methods using metal additive manufacturing result in distortion and cracking due to rapid cooling and tempering-induced hardness fluctuations in martensitic structures, leading to inconsistent material properties.
Innovation Solution
The method involves controlling the temperature of iron alloy layers within the range of Ms≤T1≤Ms+α during formation to maintain an austenitic structure and controlling the base temperature within Mf−β≤T2≤Mf to prevent martensitic transformation, thereby reducing heat distortion and achieving a uniform, high-strength martensitic structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the formed iron alloy layer is rapidly cooled to achieve martensitic structure, then the strength of the iron alloy is improved, but distortion or crack occurs due to heat shrinkage exceeding volume expansion
Solution Approach 1:
The patent changes the temperature parameters during the forming process by controlling the layer temperature to remain at or above the martensitic transformation start temperature (Ms) and the base temperature to be at or below the martensitic transformation finish temperature (Mf). This parameter control prevents premature martensitic transformation and the associated harmful shrinkage, while still achieving the desired martensitic structure in the final product.
Solution Approach 2:
The patent applies preliminary heating action by maintaining the iron alloy layer temperature above the martensitic transformation start temperature during the forming process. This preliminary temperature control prevents the austenite from transforming into martensite during layer formation, avoiding the harmful shrinkage that would otherwise cause distortion or cracking.
2Strength
If additive manufacturing is performed on martensitic structure, then the hardness of the iron alloy greatly fluctuates along the lamination direction due to tempering
Solution Approach 1:
The patent changes the thermal parameters during the forming process by controlling both the layer temperature and base temperature to specific ranges. This prevents tempering of the martensitic structure during additive manufacturing, ensuring uniform hardness along the lamination direction while maintaining high strength properties.
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
This approach effectively suppresses distortion and cracking, ensuring a uniform and high-strength martensitic structure is achieved by maintaining an austenitic state during the additive manufacturing process.
Implementation Method 1
by irradiating raw material powder of the iron alloy with either a laser beam or an electron beam and melting the raw material powder
Implementation Method 2
by irradiating raw material powder of the iron alloy with either a laser beam or an electron beam and melting the raw material powder
Implementation Method 3
The first temperature is set to a temperature higher than the second temperature and equal to or more than a martensitic transformation finish temperature Mf, and the second temperature is set to a temperature equal to or less than the martensitic transformation finish temperature Mf. The above heating causes martensitic transformation in the iron alloy layer(s), and the iron alloy layer(s) changes into a martensitic structure.
Data Source
AI summary
An iron alloy manufacturing method which can suppress occurrence of distortion and crack in formed iron alloy layers is provided. During execution of a forming step, in a first temperature control step, an iron alloy layer temperature T1 of a predetermined number of laminated layers from a surface layer of iron alloy layers formed in the forming step is controlled to be kept within a range of Ms≤T1≤Ms+α, and in a second temperature control step, a base plate temperature T2 is controlled to be kept within a range of Mf−β≤T2≤Mf.