Mechanical analysis
(nano) Hardness tests (Vickers and Brinell)
Hardness testing enables the evaluation of material’s properties, such as strength, ductility and wear resistance. A hardness test is typically performed by pressing a specifically dimensioned and loaded object (indenter) into the surface of the material you are testing. The hardness is determined by measuring the size of the impression left by the indenter.
Tensile test
Tensile testing allows to get information about the tensile strength, yield strength and ductility of the metallic material. Different deformation rates can be applied from 0.0001 mm/min up to 500 mm/min with a maximum load capacity of 50 kN.
3 point bending tests (3PB)
Three-point bending testing is a technique favored for brittle materials. For this, a constant transverse loading speed is applied on a beam-shaped sample, which causes a maximum tension to exist at the convex surface. The bending tests can be performed with four different testing conditions: (1) in air, (2) with H charging during the bending test (in-situ), (3) pre-charged with H until saturation and continued in-situ charging during the bending test (saturated in-situ), (4) within a corrosive environment with possibility of corrosion monitoring or applied ICCP. By comparing the results obtained by tests performed in air and performed in a H-rich environment, the embrittlement index (EI) can be calculated. In an analogous fashion, property degradation can be calculated, resulting from corrosion.
4 point bending tests – Incremental Step Loading (4PB - ISL)
Four-point bending testing is similar to the three-point bending. However, due to the supports’ configuration there is a constant bending moment between the inner rollers. Therefore, the region where the fracture will occur is predetermined. The Incremental Step Load Tests (ASTM F1624) give the Hydrogen Embrittlement threshold. For this, a notched specimen is tested in an environmental cell for hydrogen charging in situ. The threshold is determined by comparing the Fast Fracture Strength (in air) and the subsequent in-situ tests.
4 point constant bending test (4PCB)
Four-point constant bending test is widely used in the oil and gas industry to evaluate the resistance of metals to sulfide stress cracking (SSC) and stress corrosion cracking (SCC). In this test, the surface of the specimen that would be exposed to the service environment is placed under tensile stress, while the opposite surface is under compression. The specimen is held at a constant displacement for a specified exposure period. The test can be performed with or without H2S and/or CO2, depending on the purpose of the study.