Hardenability Tendency
Hardening tendency describes how quickly a material can form brittle martensite during cooling. High hardening tendency leads to a high martensite content and increases hardness, but also the risk of cracking.
Physical-Chemical Mechanism of Action
When rapidly cooling from the austenitic region, the steel quickly transforms into martensite. This process depends on the alloy composition and the cooling rate.
Metallurgical Relevance & Welding Risks
A high hardening tendency can lead to a high martensite content, which increases hardness. However, this can also lead to cracks and hot cracks in the material, especially if the cooling rate is too fast.
Workshop Practice & Action Guidelines
To achieve an optimal balance between hardness and dimensional stability, the cooling rate should be controlled. For high-hardening steels (e.g., high-strength steels), it is important to cool the weld slowly to ensure sufficient austenite formation. This can be achieved by using cooling water or special cooling jackets.