Assessment of the hydrogen induced stress cracking resistance of precipitation hardened nickel-based alloys using the slow strain rate tensile test method - Experimental parameters and related issues

• Within the framework of a Joint Industrial Project (JIP) sponsored by several petroleum companies, the behavior of several Precipitation Hardened (PH) Ni-based alloys with respect to Hydrogen Induced Stress Cracking (HISC) resistance was studied using the Slow Strain Rate Tensile (SSRT) test method under hydrogen charging conditions. The experimental conditions included a 0.5M sulfuric acid solution at 5 mA/cm2 and at 40°C at a strain rate of 10-6 sec-1. A round robin was performed that highlighted the need to measure the effective strain rate of the specimen during the elastic part of the SSRT test, the cell configuration, the current density, the gas cap composition, were all studied to determine the effects on the results. Once the test conditions had been optimized, the study of different industrial heats was carried out on specimens sampled in three locations, 120 degrees apart and at mid radius. It was found that sampling different areas could lead to changes in the test results, resulting mainly from microstructural variances at different locations of the bar. The results generated in this program could then be studied by relating plastic elongation obtained under CP as well as cracking mode and microstructure compliance with the API 6A CRA standard.

Nyckelord

HISC

Precipitation Hardened Ni-based alloys

SSRT

Density of gases

Hardening

Hydrogen

Metal testing

Nickel alloys

Petroleum industry

Precipitation (chemical)

Regulatory compliance

Tensile testing

Cell configurations

Experimental conditions

Experimental parameters

Ni based alloy

Slow strain rate tensile test

Sulfuric acid solution

Strain rate

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