Narrash
is the time and slope of bringing the temperature of the object to the temperature of the maximum heating rate. The welded part must be heated with a certain amount of heat, because if the amount of heat is not taken into account, the part in question will be subjected to stress escalation due to improper heat distribution, causing stress and possible cracking.
Dami Nah Dasht (Damy Haddad)
The fixed and specific temperature at which the object is kept for a certain period of time is called the holding temperature. There is a specific temperature range for keeping the welded metal in it to reduce the stress level effectively. The holding temperature is usually determined between 600 and 760 degrees Celsius according to the material of the connecting components of the structure.
Time of Nah Dasht
The specific period of time that the object is kept at the maximum temperature is called holding time. This period of time causes the heat to be evenly distributed throughout the thickness. The appropriate holding time, which is one hour per 20 to 25 mm thickness, is required to reduce the level of residual stress and is determined according to the thickness of the joints.
Narrate Sarmich
The time and slope of bringing the object's temperature to the ambient temperature and cooling it is called the cooling rate. The cooling rate should also be considered in order to avoid stress and cracking due to improper heat distribution.