What is the fatigue strength of the bimetal liner?

Published:

2022-11-25

High temperature fatigue refers to the process of bimetallic liner plate damage to the plate fracture due to the effect of cyclic and repeatedly changing stress under high temperature. Thermal fatigue refers to that when the temperature of bimetal composite liner changes and is constrained by external forces during heating and cooling, the internal expansion and contraction deformation of the liner corresponding to itself will produce stress and damage the Jiangsu bimetal liner. When heating and cooling repeatedly and rapidly, the stress will have impact, and the stress generated will be greater than that under normal conditions. At this time, some bimetal lining plates will be brittle. This phenomenon is called thermal shock. Thermal fatigue is similar to thermal shock, but the former is mainly accompanied by large plastic strain, while the latter is mainly brittle failure. The composition and heat treatment conditions of bimetal composite liner plate have influence on high temperature fatigue strength. Especially when the carbon content increases, the high temperature fatigue strength is obviously improved, and the solution heat treatment temperature also has a significant impact. Generally speaking, ferritic bimetallic liner has good thermal fatigue performance. In the austenitic Jiangsu bimetallic liner, the grades with high silicon and good extensibility at high temperatures have good thermal fatigue properties. The smaller the thermal expansion coefficient, the smaller the strain under the same thermal cycle, the smaller the deformation resistance and the higher the fracture strength, the longer the service life. It can be said that the fatigue life of martensitic bimetallic liner 1Cr17 is longer, while the fatigue life of austenitic liner plates such as 0Cr19Ni9, 0Cr23Ni13 and 2Cr25Ni20 is shorter. In addition, castings are more likely to be damaged due to thermal fatigue than forgings. At room temperature, the 107 times fatigue strength is 1/2 of the tensile strength. Compared with the fatigue strength at high temperature, there is not much difference in the fatigue strength from room temperature to high temperature.