Mecatheque
Results of collective works
Hardening cracks: understanding cracking mechanisms
This study aimed at providing technical grounds for "usual practices" applied in production workshops to avoid hardening cracks. Therefore, this study aimed at better understanding why these hardening cracks appeared further to surface induction heating and was based on the generation of tensile stresses at the end of the heat affected zone. The conclusion of the different tests was as follows: in addition to the impact of stress concentrations due to geometrical parameters (part shape, surface condition), the two following parameters must be taken into account to understand the reason for the appearance of cracks: the plastic capacity of partially-transformed or untransformed material and the submission of the structure to compression stress further to thermo-kinetic and metallurgical processes. According to the test results, it is extremely important to control the cooling kinetics of the parts and to take steel hardenability and the metallurgical condition of the material prior to surface heating into account.
