Heat Accumulation Factor
The heat accumulation factor corrects the cooling time t8/5 in multi-pass welds and limited plate sizes due to preheating. It helps control the microstructure and avoid cracks.
Physical-Chemical Mechanism of Action
The heat accumulation factor (WAF) accounts for the additional heat in multi-pass welds. This extra heat can lead to more uneven cooling and alter the microstructure.
Metallurgical Relevance & Risks in Welding
Too fast cooling with a high WAF can lead to glass-hard martensite, which may cause cracks and fracture points. Too slow cooling can coarsen the grain and reduce the toughness of the steel.
Workshop Practice & Instructions
To use the WAF correctly, follow these steps:
1. Determine the actual cooling time t8/5 considering the WAF.
2. Use a controlled cooling method to ensure even cooling.
3. Monitor the temperature curve and correct the cooling steps if needed.