Effect of 4-(N,N-diethylamino)benzaldehyde thiosemicarbazone on the corrosion of aged 18 Ni 250 grade maraging steel in phosphoric acid solution

The corrosion inhibition of the aged 18 Ni 250 grade maraging steel in 0.5 M sulfuric acid by 3,4-dimethoxybenzaldehydethiosemicarbazone(DMBTSC) has been investigated by potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) techniques. The inhibition efficiency increased with the increase in inhibitor concentration and decreased with the increase in temperature. Polarization curves indicated mixed type inhibition behavior affecting both cathodic and anodic corrosion currents. The thermodynamic parameters of corrosion and adsorption processes were evaluated. The adsorption of DMBTSC on the aged maraging steel surface was found to obey the Langmuir adsorption isotherm model, and the calculated Gibb’s free energy values confirm the spontaneous adsorption. The results obtained by the two techniques were in good agreement.

3,4-Dimethoxybenzaldehydethiosemicarbazone as corrosion inhibitor for aged 18 Ni 250 grade maraging steel in 0.5 M sulfuric acid

Friction stir welding: An alternative to fusion welding for better stress corrosion cracking resistance of maraging steel

Effect of cathodic polarisation on stress corrosion cracking behaviour of a Ni(Fe, Al)-maraging steel in artificial seawater

In the heat-treated condition, 18% Ni maraging steels have a microstructure of aged martensite and essentially no austenite. However, austenite can form if the material is overaged. This has been termed as austenite reversion, a subject which has received much attention, because it importantly influences properties and performance of the steel. Reversion of austenite in fusion zones of weld joints in these steels has also been widely studied. Because of microsegregation, austenite reversion in the fusion zone is accelerated. Reverted austenite in the fusion zone strongly influences the performance of the weld joints. The present review critically analyses the published work on austenite reversion and its effects on properties and performance, covering both base metal and weld joints.

Austenite reversion in 18% Ni maraging steel and its weldments

The stress corrosion characteristics of 18 wt-%Ni (MDN-250) maraging steel and its weldments made under different welding conditions have been investigated. The threshold stress intensity factor K ISCC in stress corrosion conditions has been determined in 3.5 wt-%NaCl environment for the base metal and weldments. The fractured surfaces were analysed to study the types of fracture during stress corrosion cracking in base and weld metals. Fracture toughness tests were carried out and the results obtained from these tests have been compared with K ISCC values.

K. Y. Sastry

Papers

Stress corrosion cracking of maraging steel weldments