Mokume-gane (wood-grained metal) is an ancient Japanese metalworking technique involving the diffusion bonding of pure metals and alloy sheets into a billet that is forged, rolled and patterned, resulting in patterned materials. In 2005, James Binnion, Andrew Nyce and Stewart Grice studied diffusion bond strength as a function of open and closed torque plate bonding apparatus, utilizing the newly developed Thermal Expansion Mismatch Torque Plate system (TEMTP). Their paper demonstrated that the TEMTP system resulted in increased bond strength as compared to the open torque plate system. However, the authors did not include downstream processing within the scope of their study, nor did they consider the effects of time and temperature on bond strength. This study is a continuation of the work they began and includes the effects of time and temperature and selected downstream processing techniques on bond strength, where bond strength was measured by rolling samples to failure on edge. Based on the results of this study, it was found that longer firing cycles produce stronger bonds. Cold forging, either by hand or using a hydraulic press, produces bonds that were among the strongest of the tested methods of reduction. Hot and cold forging using the hydraulic press creates strong materials. Hot forging takes advantage of the elastic deformation of the heated billet, which allows for much greater reductions. This method is a good fit for the small, well-equipped shop. Cold rolling, as accomplished with the smaller diameter rolls of the typical small shop rolling mill, seems to be less than adequate when compared to hot and cold forging.

Author: Dr. Cóilín Ó Dubhghaill, Dr. A. Hywel Jones