Hardness Based Creep Life Prediction for 2.25Cr-1Mo Superheater Tubes in a Boiler

Abstract

Fig. 1.MHP-s correlation for new and service-exposed 2.25Cr-1Mo tubes.

Creep characterization and damage assessment of long term service exposed P-22 grade of steel

“…The long term creep rupture lifetime is often estimated using shortterm creep rupture data. Some past observation of remnant life on service exposed materials has been reported in literature [3][4][5][6][7][8]. But in these studies scatter characteristic of service exposed material is not taken into account for damage/remaining life assessment.…”

Incorporating specific batch characteristics such as chemistry, heat treatment, hardness and grain size into the Wilshire equations for safe life prediction in high temperature applications: An application to 12Cr stainless steel bars for turbine blades

“…The breakpoint does not seem to be determined by any of the batch characteristics so the variation in this breakpoint between the batch must be just random in nature.  or the variation in failure times for each batch, is predominantly determined by x 2 , x 7 x 12 and x 16 which are the Rockwell hardness of the batch, the P content of the batch, the Cu content of the batch and whether that batch went through heat treatment 2. These loading were then used to form the q partial least squares components 1q T given by Eq.…”

“…The activation energy (b 2 ) has a very strong systematic component with 84.6% of the batch to batch variation in b 2 being explained by T 12 with the remaining random variation measured by   u2 = 109.5. The scale parameter also has a very strong systematic component with 83.0% of the batch to batch variation in s being explained by T 16 with the remaining random variation measured by   u6 = 0.01. Even the break point seems to be well predicted by the partial least squares component T 15 .…”

“…al. [16] found that for 2.25Cr-1Mo steel the Larson Miller parameter was a quadratic function of the log of the pre service Vickers hardness measurement, so allowing life times to be predicted from the initial hardness and stress/temperature conditions. In principal it is possible to incorporate into the Wilshire equation specific batch characteristics such as its chemical composition, the heat treatment it has been subjected to, the grain size, the frequency of inclusions and its hardness to predict the creep properties of that particular batch.…”

“…Notice that at temperature 723K the median failure time prediction obtained when ignoring the batch specifics of RBH underestimates the actual failure times for specimens cut from this batch. However, when the batch characteristics of RBH are combined with the loading values in Table 3, specific values for T 11 to T 16…”