研究目的
To determine the influence of heating rate on transitions occurring during the heating cycle in 18-Ni steel components fabricated by selective laser melting technique.
研究成果
The martensite reversion to austenite transition in analysed compounds discloses a trend to split into two stages for low heating rates. The activation energy of 301 kJ mol?1 was found out for the precipitation of intermetallic phases. For the reversion of martensite to austenite, the activation energy of 478 kJ mol?1 was found. The non-isothermal dilatometric method can be taken into consideration as a uncomplicated substitute for labour-intensive and time-consuming isothermal hardness analysis.
研究不足
The study is limited to the analysis of phase transitions in 18-Ni steel components fabricated by selective laser melting technique under controlled heating and cooling cycles. The influence of heating rate on transitions is investigated, but other factors such as cooling rate and material composition variations are not considered.
1：Experimental Design and Method Selection:
Dilatometric studies were carried out to analyze the phase transitions in 18-Ni steel components fabricated by selective laser melting technique. The heating and cooling cycles were controlled, with heating rates of 10, 15, 20, 30, and 60 °C min?
2：Sample Selection and Data Sources:
Cylindrical samples 4 mm in diameter and 10 mm long were manufactured from 18-Ni 300 steel supplied by B?HLER as a gas-atomised powder.
3：List of Experimental Equipment and Materials:
A BAHR DIL805 A/D dilatometer was used for the experiment, along with a RENISHAW AM125 AM system for sample preparation.
4：Experimental Procedures and Operational Workflow:
Samples were heated in a low vacuum to 900 °C at different heating rates, with temperature and length changes captured during heating. The Savitzky–Golay method was used for signal smoothing.
5：Data Analysis Methods:
The Kissinger equation was used to determine the activation energy of individual reactions.
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