Impurity Element Control Parameter
Tramp element control parameters are technical limits for unwanted trace elements such as tin, antimony, arsenic, and bismuth in the weld. These parameters prevent temper embrittlement and improve strength.
Physico-chemical mechanism of action
Tramp elements such as tin (Sn), antimony (Sb), arsenic (As), and bismuth (Bi) can appear as trace elements in the weld. These elements can alter the steel's structure, especially the formation of martensite and austenite. A too high concentration of these tramp elements can cause the temper (the core of the weld) to embrittle, thereby reducing its strength.
Metallurgical relevance & risks in welding
A too high concentration of tramp elements can lead to the following problems:
• Temper embrittlement: The temper (the core of the weld) becomes brittle, reducing the strength and toughness of the weld.
• Crack formation: The brittleness of the temper increases the risk of cracks, especially hot cracks.
• Coarsened grain structure: A too high concentration can also cause the grain of the weld to coarsen, further impairing toughness.
Workshop practice & action instructions
To effectively handle tramp element control parameters, the following measures should be taken:
• Melt pool control: Ensure the melt pool contains the right additions to control unwanted tramp elements.
• Material selection: Choose materials with low concentrations of tramp elements or use materials without these elements.
• Set welding parameters: Adjust welding parameters like temperature and time to properly control tramp elements.
• Post-inspection: After welding, inspect the weld quality for temper embrittlement and crack formation.