Effects of Ti and Cu Addition on Inclusion Modification and Corrosion Behavior in Simulated Coarse-Grained Heat-Affected Zone of Low-Alloy Steels

Abstract

In this paper, the effects of Ti and Cu addition on inclusion modification and corrosion behavior in the simulated coarse-grained heat-affected zone (CGHAZ) of low-alloy steels were investigated by using in-situ scanning vibration electrode technique (SVET), scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS), and electrochemical workstation. The results demonstrated that the complex inclusions formed in Cu-bearing steel were (Ti, Al, Mn)-Ox-MnS, which was similar to that in base steel. Hence, localized corrosion was initiated by the dissolution of MnS. However, the main inclusions in Ti-bearing steels were modified into TiN-Al2O3/TiN, and the localized corrosion was initiated by the dissolution of high deformation region at inclusion/matrix interface. With increased interface density of inclusions in steels, the corrosion rate increased in the following order: Base steel ≈ Cu-bearing steel < Ti-bearing steel. Owing to the existence of Cu-enriched rust layer, the Cu-bearing steel shows a similar corrosion resistance with base steel.

Local Corrosion Behaviors in the Coarse-Grained Heat-Affected Zone in a Newly Developed Zr–Ti–Al–RE Deoxidized High-Strength Low-Alloy Steel

“…AF is staggered, interlocked and formed on non-metallic inclusions. The M/A constituent is a mixture of untempered martensite embedded in carbon-enriched retained austenite [ 4 , 5 ]. As a result, the CGHAZ is considered to be the weakest area in the welded joint [ 6 ].…”

“…Generally, the types of non-metallic inclusions—such as Al 2 O 3 , MnS, ZrO 2 , CaO and Al 2 MgO 4 —introduced in steels depend on the specific deoxidation techniques [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Inclusions in the steels are often considered as defects that can preferably be attacked by chloride ions in the marine environment, which induce pitting corrosion [ 4 , 16 , 17 ] that has a detrimental impact on application performance [ 18 , 19 , 20 , 21 , 22 , 23 ]. Numerous studies have been conducted on the local corrosion caused by inclusions in HSLA steels.…”

Effect of Cu on the Formation of Reversed Austenite in Super Martensitic Stainless Steel

“…However, some researchers believe it is related to anodic polarization. Studies have shown that only 0.1 wt.% of Cu can significantly improve the atmospheric corrosion resistance of steel [ 16 , 17 , 18 , 19 ]. To date, few studies have reported the effect of Cu on the formation of reversed austenite in super martensitic stainless steel.…”

Special Issue: Corrosion Properties and Mechanism of Steels

“…Park et al [ 10 ] examined the hydrogen-induced cracking caused by galvanic corrosion of an ASTM A516-65 steel weld in a wet sour environment using a combination of a standard immersion corrosion test, electrochemical analyses and morphological observation of the corrosion damage. Wang et al [ 11 ] investigated the effects of Ti and Cu addition on inclusion modification and corrosion behavior in the simulated coarse-grained heat-affected zone of low-alloy steels by using an in situ scanning vibration electrode technique, a scanning electron microscope/energy-dispersive X-ray spectroscopy and an electrochemical workstation. The corrosion feature of Q235B steel in desulfurization solution is studied by Gong et al [ 12 ].…”