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The post weld heat treatment (PWHT) was used to reduce the level of the residual stresses and increase of the crack resistance of the material in the connection part.The article presents the results of the residual stress measurements immediately after welding and after the stress relaxation by the PWHT.

The post weld heat treatment (PWHT) was used to reduce the level of the residual stresses and increase of the crack resistance of the material in the connection part.The article presents the results of the residual stress measurements immediately after welding and after the stress relaxation by the PWHT.

In the process of testing teal components exposed to elevated temperature, it is hot possible to neglect Cracks. The most significant cracks can be induced by welding, which is applied for joining of Structural components. Pressure equipment in service is also exposed to high pressure and high stresses. Materials for their manufacturing are designed to resist high stress at elevated temperature, and to meet requirements regarding creep resistance. The objective of this study is to investigate microstructure of different regions of the heat affected zone in T/P91 steels by using thermal simulation instead of welding.

The subject of this paper is the microstructural and mechanical characterisation of regions of the heat-affected zone (HAZ) in steels containing 9-12% Cr that are used for operation at elevated temperatures. Tests were performed on regions in the HAZ, which was created by physical simulation using a thermal welding simulator. Half of the simulated samples (SSs) were tested at room temperature (RT) and at an operating temperature (OT) of 600 degrees C immediately after simulation/welding, while the rest of the simulated samples were tested at RT and at the OT after heat treatment following the welding, i.e., post-weld heat treatment (PWHT). In addition to the results from mechanical testing, the results from microstructural analysis using light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are also presented. The manner in which PWHT contributes to the creep resistance of the HAZ in P91 steel is demonstrated.

The subject of this paper is the microstructural and mechanical characterisation of regions of the heat-affected zone (HAZ) in steels containing 9-12% Cr that are used for operation at elevated temperatures. Tests were performed on regions in the HAZ, which was created by physical simulation using a thermal welding simulator. Half of the simulated samples (SSs) were tested at room temperature (RT) and at an operating temperature (OT) of 600 degrees C immediately after simulation/welding, while the rest of the simulated samples were tested at RT and at the OT after heat treatment following the welding, i.e., post-weld heat treatment (PWHT). In addition to the results from mechanical testing, the results from microstructural analysis using light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are also presented. The manner in which PWHT contributes to the creep resistance of the HAZ in P91 steel is demonstrated.

In the process of testing teal components exposed to elevated temperature, it is hot possible to neglect Cracks. The most significant cracks can be induced by welding, which is applied for joining of Structural components. Pressure equipment in service is also exposed to high pressure and high stresses. Materials for their manufacturing are designed to resist high stress at elevated temperature, and to meet requirements regarding creep resistance. The objective of this study is to investigate microstructure of different regions of the heat affected zone in T/P91 steels by using thermal simulation instead of welding.

In this investigation we look at the influence of the local residual stresses caused by Vickers-pyramid indenting on the initiation and early propagation of small cracks from indentations in coarse-grain martensitic steel. The size of these indentations is comparable to the grain size. Specimens with and without a local residual stress field were tested on a rotary bending machine. A focused ion beam and a scanning electron microscope were used to reveal the influence of those stresses on the location of the cracks' initiation and the mechanism of the small-crack propagation. The existing local residual stresses assist in the initiation of two cracks at a level lower than the fatigue limit. The early small-crack propagation is gradually obstructed by the residual stress-field configuration until the cracks become non-propagating cracks. At levels higher than the fatigue limit, both cracks succeed in breaking through the compressive stressed domain and link together. From that moment the crack begins to behave as a long crack, penetrating outside the indentation into the tensile-stressed domains.

In this investigation we look at the influence of the local residual stresses caused by Vickers-pyramid indenting on the initiation and early propagation of small cracks from indentations in coarse-grain martensitic steel. The size of these indentations is comparable to the grain size. Specimens with and without a local residual stress field were tested on a rotary bending machine. A focused ion beam and a scanning electron microscope were used to reveal the influence of those stresses on the location of the cracks' initiation and the mechanism of the small-crack propagation. The existing local residual stresses assist in the initiation of two cracks at a level lower than the fatigue limit. The early small-crack propagation is gradually obstructed by the residual stress-field configuration until the cracks become non-propagating cracks. At levels higher than the fatigue limit, both cracks succeed in breaking through the compressive stressed domain and link together. From that moment the crack begins to behave as a long crack, penetrating outside the indentation into the tensile-stressed domains.