Materials and Testing Equipment for Cone Bit
The steel components of carburized cone bits are produced through die forging, machining, deep carburization, and heat treatment. All test specimens are sourced from actual cone bit bodies and processed into metallographic samples via wire cutting. Hardness is measured using an HR-150A hardness tester for both the carburized surface and core of the samples. The microstructure of the carburized layer is observed with a Nikon EPIPHOT 300 metallographic microscope, using a 4% nitric acid-alcohol solution as the etchant. Phase analysis of the carburized layer surface and regions distant from it is conducted using an XRD-6000 X-ray diffractometer.
Hardness Testing of Carburized Cone After Heat Treatment
Samples from the cone bit body are carburized, and hardness is measured for both the carburized layer and core. Post-carburization and heat treatment, the carburized layer achieves a hardness of HRC 58–59, while the core hardness ranges from HRC 44–45. Per heavy-duty gear industry standards, carburized gear surface hardness should be HRC 58–62, with core hardness between HRC 30–46. The carburized cone meets the hardness requirements for both surface and core.
XRD Phase Analysis of Carburized Layer and Core
XRD diffraction analysis is performed on the carburized layer and non-carburized core of the heat-treated cone samples. The carburized layer exhibits primarily ferrite and austenite peaks, indicating a microstructure of martensite and retained austenite after heat treatment, with no carbide peaks detected, suggesting minimal or no carbide presence. The core shows ferrite and austenite peaks as well, confirming a martensite and retained austenite structure. The key difference in XRD patterns is the lower intensity of austenite peaks in the core, where peak intensity correlates with phase proportion. Higher peak intensity indicates a greater phase fraction, revealing that the carburized surface layer contains more retained austenite than the core.
Post time: Mar-21-2025
