Improving the impact toughness of heavy-duty gear steel by rare earth addition
Source abstract
Abstract
: This study aims to investigate the role of rare earth (RE) elements in impact toughness of heavy-duty gear steel. For this purpose, heavy-duty gear steels with varying RE contents were prepared and systematically analyzed after undergoing the same carburizing process. The results demonstrate that a small amount of RE addition can modify irregular Al 2 O 3 and MnS inclusions into RE inclusions, accompanied with the significantly reduced inclusion size and increased inclusion number. As the RE content increases, the reaction sequence of potential inclusion forming elements with RE elements is O, S, As and P successively. Both the average size of inclusions and the number percentage of large inclusions increase, and the inclusion growth mode gradually shifts from precipitation growth to aggregation growth. Furthermore, RE treatment can increase the carbon concentration in the carburized layer, leading to an increased volume fraction of retained austenite (RA) in the carburized layer and microstructure refinement for RE-treated steels. Consequently, the impact toughness of carburized gear steel increases first and then decreases with an increasing RE content, and the highest impact toughness occurs at 0.0078 wt.% RE content with an about 21% increase. The improved impact toughness for RE-treated steels mainly benefits from the tiny inclusions alleviating stress concentration and more RA transformation. However, excessive RE addition generates more large inclusions, resulting in easier impact cracking and low impact toughness.
Source: openalex_inverted_index · Quality: baseline
Research context
OpenAlex topics: Microstructure and Mechanical Properties of Steels · Metal Alloys Wear and Properties · Metallurgical Processes and Thermodynamics
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
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