ESTIMATION METHOD OF RESIDUAL LIFE OF HOLLOW METAL PART, HAVING WORKED UNDER CREEPING CONDITIONS AT HIGH PROCESS TEMPERATURE AND PRESSURE

摘要

FIELD: test equipment.;SUBSTANCE: after the equipment is stopped, the time τ_e from the indicated part operation start up to the indicated stop of exploitation is fixed, check if there are any microdamages in various areas of the outer surface of the controlled part, as well as the maximum level of the microdamage in the most damaged area. The target value of the residual life is calculated bythe mathematical relation τ_rl=K_rl⋅τ_e, where K_rl - residual life coefficient, determined on the basis of its experimental dependence on the level of microdamage Ω_cp of the controlled part. The section of the metal is cut from the least loaded part of the controlled part to produce the round section samples series, each of the samples is tested for creeping before fracture with the continuous load at the temperature above the operating value during the CP operating process. Based on the test results of these samples, plot the graphical dependence of the sample microdamage level Ω_sam from the worked out durability share τ_wds=τ_i/τ_k, where τ_i - is the current time from the test start, τ_k - time from the tests start up to the sample fracture. For several points (i) of the indicated graphical dependence, calculate the values of the residual life coefficient K_rl of the sample, starting from the mathematical relation τ_rli=K_rli⋅τ_i, where τ_rli=τ_k⋅(_1-τ_wds). Plot the new graphical dependence of K_rl=f(Ω_sam) with the exception of the time parameter. Calculate the residual life of the controlled part, use the mathematical ratio τ_rl=K_rl⋅τ_e, where K_rl is defined from the specified graphical dependence according to the K_rl=f(Ω_sam). The series consists of at least two pairs of samples. One of the samples of each pair is left solid, and the other is made with the annular tapped notch in the central part, that simulates in the known way the specified value of the controlled part surface microdamage, so that the sample section damage by the indicated annular notch level ω corresponds to the microdamage level Ω. The samples tests are done at the specific load within the range 0.9-1.1 of the operating value and the temperature for each subsequent pair higher than the previous one by 10-50°C. The minimum from these indicated temperatures is selected from the condition, that the time up to the fracture of the sample does not exceed 6200 hours. The sample with the annular notch of each pair selected for testing is given its own value ω. When plotting the indicated dependence of the microdamage level Ω_sam=f(τ_wds), the solid sample relative loading time of each mentioned pairs prior its rupture on the mentioned graphical relationship is fixed as τ_k=1, and the relative loading time of the sample with the annular notch prior to its destruction - as τ_wds.;EFFECT: elimination of the intermediate stops and measurements necessity during the samples testing.;6 dwg, 3 tbl