Nonlinear ultrasonic characterization of intergranular corrosion damage in super 304H steel tube

Abstract

Purpose

Super304H steel is a new fine-grained austenitic heat-resistant stainless steel developed in recent years, and it is widely used in high temperature section superheater and reheater tubes of ultra-supercritical thermal power units’ boiler. Currently intergranular corrosion (IGC) has occurred in a few austenitic stainless steel tubes in ultra-supercritical units and led to boiler leakage. The purpose of this paper is to find a nondestructive method to quickly and easily detect IGC of austenitic stainless steel tube.

Design/methodology/approach

This paper uses the nonlinear characteristics of ultrasonic propagation in steel tube to detect the IGC of Super304H tube.

Findings

The experimental results show that the nonlinear coefficient generally increases sensitively with the degree of IGC; hence, the nonlinear coefficient can be used to assess IGC degree of tubes, and the nonlinear coefficient measurement method is repeatable for the same tube.

Research limitations/implications

A theory of how IGC would affect the ultrasonic signals and lead to a nonlinear response needs further research.

Practical implications

A nondestructive method to quickly and easily detect IGC is provided.

Social implications

Using ultrasonic nonlinear coefficient to assess IGC degree of tubes is a new try.

Originality/value

This paper provides a new way to test IGC.

Citation

Zhong, F., Zhang, C., Li, W., Jiao, J. and Zhong, L. (2016), "Nonlinear ultrasonic characterization of intergranular corrosion damage in super 304H steel tube", Anti-Corrosion Methods and Materials, Vol. 63 No. 2, pp. 145-152. https://doi.org/10.1108/ACMM-05-2014-1390