Effect of Material Heterogeneity on Environmentally Assisted Cracking Growth Rate of Alloy 600 for Safe-End Welded Joints.

Kuan Zhao,Shuai Wang,He Xue,Zheng Wang

doi:10.3390/ma14206186

Abstract

Environmentally assisted cracking (EAC) is essential in predicting light water reactors’ structural integrity and service life. Alloy 600 (equivalent to Inconel 600) has excellent corrosion resistance and is often used as a welding material in welded joints, but material properties of the alloy are heterogeneous in the welded zone due to the complex welding process. To investigate the EAC crack growth behavior of Alloy 600 for safe-end welded joints, the method taken in this paper concerns the probability prediction of the EAC crack growth rate. It considers the material heterogeneity, combining the film slip-dissolution/oxidation model, and the elastic-plastic finite element method. The strain rate at the crack tip is a unique factor to describe the mechanical state. Still, it is challenging to accurately predict it because of the complicated and heterogeneous material microstructure. In this study, the effects of material heterogeneity on the EAC crack growth behavior are statistically analyzed. The results show that the material heterogeneity of Alloy 600 can not be ignored because it affects the prediction accuracy of the crack growth rate. The randomness of yield strength has the most influence on the EAC growth rate, while Poisson’s ratio has the smallest.

Highlights

Due to their outstanding corrosion resistance and excellent mechanical properties in high-temperature and wet corrosive environments, nickel-based alloys are widely used as welding consumables in the safe-end welded joints [1,2]
Xue et al [9,10] proposed an approach for the quantitative prediction of Environmentally assisted cracking (EAC) crack growth rate
The normal plastic strain ε22 p in front of the crack tip is often adopted as the primary mechanical parameter influencing the EAC crack growth rate prediction

Summary

Introduction

Due to their outstanding corrosion resistance and excellent mechanical properties in high-temperature and wet corrosive environments, nickel-based alloys are widely used as welding consumables in the safe-end welded joints [1,2]. Dozens of mechanisms and predictive models have been proposed for EAC crack propagation [5,6,7], and the slip-dissolution/oxidation model has been widely accepted as a reasonable EAC description of the critical materials in nuclear plants [8]. Xue et al [9,10] proposed an approach for the quantitative prediction of EAC crack growth rate. In this method, the selection of characteristic distance r0 is essential. It is difficult to accurately predict it because the material microstructure is complicated and heterogeneous [12]

Objectives

Results

Conclusion