Quench Sensitivity
Hardening sensitivity describes how much the mechanical properties of a steel are affected by slow cooling.
Physical-Chemical Mechanism of Action
Hardenability is a property of metals that shows how their mechanical properties (such as hardness and toughness) are impaired during slow cooling. In steels, slow cooling forms a finely branched structure with many small grains, which reduces toughness.
Metallurgical Relevance & Welding Risks
High hardenability leads to a coarser structure and lower toughness of the weld. This can cause cracks, hot cracks, or reduced component life. It is especially dangerous in steels with high carbon content.
Workshop Practice & Action Instructions
To minimize hardenability, cooling of the weld should be as fast as possible. This can be achieved by using cooling water or special cooling gases. For steels with high hardenability, it is important to observe the maximum cooling rate and possibly use a protective cooling layer (e.g., paint).