# Stress Corrosion Cracking Analysis of a Hot Blast Stove Shell with an Internal Combustion Chamber
## 3 Results and Discussion
### Discussion  
The characteristics of SCC change significantly depending on temperature and acid condensation. It is worth noting that, as the temperature increases, the CPR increases, from which it can be found that the damage expands as the temperature changes. Furthermore, acid condensation can lead to low-temperature corrosion (LTC) that can pose a safety threat. The model presented in this study aims to predict the stress corrosion cracking (SCC) growth rates, which can cause significant safety and economic issues due to their generality and severity. Additionally, the model predicts the distribution of these growth rates. Surface mobility mechanisms showed that an SCC mechanism should abide by first principles and account for the most appropriate variables, like temperature, environment composition, and stress.  
Therefore, based on this fundamental characteristic, this paper aimed to study the characteristics of the SMM under operating conditions and added some impact factors to improve the performance of convenient and relatively accurate predictions. Considering that the method in this study is proposed to study the growth of cracks initiated from mechanical stress-caused notch, this indicates the possibility that the proposed CPR prediction procedure has very high accuracy and can be widely used in practical prediction applications under harsh and extreme operating conditions.  
Similarly, even though the tendency of the CPR to increase the higher temperature is the same as the specimen experiment tendency, some more detailed results should be considered by adding more operation conditions to set up a series of operation rules. The  
Figure 8: The average crack propagation rates for (**a**) reference blast temperature and for the blast temperature increased by (**b**) 45 K and (**c**) 90 K through an operation cycle. (**d**) The comparison of the maximum crack propagation rate for the different blast temperatures.  
Figure 9: Maximum principal stress of the shell on the conical part along the circumferential direction for the reference blast temperature [28] and for the blast temperature increased by 45 K and 90 K.  
analysis results can provide insight into limiting the region to be inspected and monitored in the HBSs.  
In all cases analysed in this study, the probability of showing the SCC is higher in the conical region. [PERSON] and [PERSON] [41] reported that the SCC occurred in the weld line of the combustion chamber of the external combustion HBS. From their study, it was found that the SCC occurred from the nitric and sulfuric acids with the residual stress in the heat-affected zone of the weld line. Even the residual stress from welding was not considered in this study; the thermo-mechanical stress can also initiate the SCC with the acidic condensates in the internal-combustion HBS. Therefore, monitoring the weld lines around the conical region of the internal-combustion HBS can be important from the safety management point of view.  
The general relationship with the temperature was considered to fill the gap in the prediction of SCC considering the acid corrosion characteristics. However, some more detailed conditions should be added to reduce the discrepancy. Meanwhile, the study of the phenomenological relationship of SCC process variables that affect SCC characteristics by significantly changing the variables is also in great demand for the future.