The invention discloses a
material repair welding method of a CB2
casting of an ultra-supercritical
turbine unit. The method comprises the following steps that firstly, high-temperature
softening tempering preheating is carried out; secondly, nondestructive inspection is carried out; thirdly, flaws are eliminated; fourthly, the portions where the flaws are eliminated are preheated; fifthly, a
welding material which is the same as and cooperates with a base material is used for performing repair
welding; sixthly, post-heating is carried out on the repair welding area; seventhly, nondestructive inspection is carried out on the repair welding area; eighthly, the austenitizing temperature is achieved through heating and then preserved, the
cooling speed of the CB2
casting is controlled after heat preservation is finished, after the
room temperature is achieved through cooling, high-temperature
tempering is performed when the temperature of the
casting is raised to about 100 DEG C below a point AC1 of a CB2 material, and the
cooling speed is controlled for achieving the
room temperature after heat preservation is finished; and ninthly, the nondestructive inspection is carried out. The procedures that the repair welding is carried out firstly, and then the performance
thermal treatment is carried out are adopted, it can be ensured that the same performance
thermal treatment process is adopted in the repair welding area and a
body area, and it is guaranteed that the performance of a welding line joint and the performance of a body are basically consistent.