Near-threshold fatigue crack growth behavior of 10% Cr martensitic steel welded joint with 9% Cr weld metal in high temperature air. (August 2020)

• Record Type: Journal Article
• Authors: Sun, Qixing; Li, Kejian; Li, Xiaogang; Rui, Shao-Shi; Cai, Zhipeng; Pan, Jiluan
• Is Part Of: International journal of fatigue. Volume 137(2020)
• Publication Date: 2020-08
• Subjects: Fatigue crack growth -- Threshold value -- Crack closure -- Martensitic steel welded joint -- High temperature air; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2020.105650
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: The Δ K th tests of a 9%–12% Cr steel welded joint were firstly performed in 538 °C air. The weld metal with the lowest Cr content had the highest Δ K th . The heat affected zone with fine grains and few laths had lower Δ K th than base metal. The Δ K th differences and stress ratios' influences were explained by crack closures. Oxide-induced crack closure of the weld metal was still influential at R = 0.7. Abstract: The near-threshold fatigue crack growth (FCG) behavior under different stress ratios (R) of a 9%–12% Cr steel welded joint was studied in 538 °C air. The most significant oxide-induced crack closure (OICC) occurred in weld metal (WM) due to the lowest Cr content, resulting in the highest threshold value (Δ K th ) of WM. The base metal (BM) with coarser grains and denser lath structures had more obvious roughness-induced crack closure (RICC) and more severe crack deflection, which led to a higher Δ K th of BM than heat affected zone (HAZ). The Δ K th of WM, HAZ and BM decreased as R increased.