Investigation of the Effect of B4C Addition on the Matrix Composition of Diamond Sockets in Granite Cutting and the Relationships Between Socket Metallographic Properties and Cuttability Parameters via SEM and Regression Analysis

Selecting diamond sockets with matrix properties compatible with the target rock is critical for cutting efficiency and cost reduction in natural stone processing. This study investigated the effect of B4C addition (0–7 wt.%) on the matrix microstructure, diamond–matrix interfacial bonding quality, and cutting performance of powder metallurgy diamond sockets used in granite sawing. Eight sockets, one undoped and seven with varying B4C contents, were sintered at 730 °C, 35 MPa, for 3 min. Unit volume weight (UVW), porosity (P), Knoop hardness (HK), and abrasion loss by weight (ALW) were determined for each composition. SEM analyses on fracture surfaces revealed significant microstructural differences with increasing B4C content. Pore sizes increased from 2–4 µm (0% B4C) to over 40 µm (7% B4C). The 4% B4C socket achieved the most uniform B4C grain distribution (3–8 µm), the highest Knoop hardness (303.46 HK), the lowest porosity (4.20%) among doped sockets, and the tightest diamond–matrix bonding. Cutting tests on Hisar Grey granite confirmed that the 4% B4C socket delivered the highest net power consumption (720.85 W) and the lowest specific wear (84.84 µc/m2), consistent with SEM observations. Regression analyses identified porosity as the single strongest predictor across all cutting parameters (r = 0.87–0.97), and abrasion loss by weight as a reliable indicator of specific wear (r = 0.98). These findings suggest that laboratory metallographic measurements may serve as useful indicators of cutting performance trends, though validation across different rock types and cutting conditions is needed before broader generalisations can be drawn.