Process for removing mixed crystal defect of large rotor forging

Abstract

This invention provides a technology that eliminates flaws of mixed crystal of low pressure rotor forging of large turbine to decrease normalizing frequency, this technology controls central temperature of forging by some specific measure to make it be in a rational temperature range at every forming heats, to avoid grain of forging centre growing anomaly, avoid creating mixed crystal flaw, decrease Follow-up normalizing frequency.

Description

technical field [0001] The invention relates to a process for eliminating mixed crystal defects of a large-scale steam turbine low-pressure rotor forging Background technique [0002] At present, in the existing technology, the production process design of large forgings mainly focuses on meeting the deformation requirements of steel ingots, and does not take enough consideration of the influence of forging heating on the performance of final products. For example, in the current 300,000-kilowatt steam turbine low-pressure rotor forging process, each forming heat has the characteristics of long heating time (18-20 hours) and high temperature (1200-1270°C). Since the diameter of the forging has reached the maximum shaft diameter of the rotor before the forming fire, the middle part of the forging will no longer be deformed after the forming fire. This heating state without forging ratio will inevitably cause the grains in the core of the rotor to grow abnormally, and the gene...

AI Technical Summary

Problems solved by technology

Since the diameter of the forging has reached the maximum shaft diameter of the rotor before the forming fire, the middle part of the forging will no longer be deformed after the forming fire. This heating state without forging ratio will inevitably cause the grains in the core of the rotor to grow abnormally, and the genetic characteristics of the material will cause mixed crystal defects. Generated, bring pressure and increase the number of normalizing times to the subsequent heat treatment

Theoretical studies and numerical simulations have shown that the current forming and secondary heating process causes the core temperature of the rotor forging to always be above 1150°C, and prolonged exposure to this temperature will inevitably lead to abnormal grain growth and the formation of mixed crystal defects