Problemy występujące podczas spawania nowej generacji stali bainitycznej 7CrMoVTiB10-10 (T24)

A dynamic development of steels for components for usc boilers used in fossil fired power plants creates new welding problems. Introduction of new combinations of alloying agents, which are used to improve mechanical properties, especially creep resistance, does not remain indifferent as to the weldability of the newest steels. Every new steel grade which will be used for pressure components in power plants boilers has to be precisely tested. The most important processes that require profound research are bending and welding. It is crucial to examine all new steel grades and use the knowledge to elaborate technologies which could be used during prefabrication and assembly of boiler installations. As an example 7CrMoVTiB10-10 also known as T/P24 is given.Dynamiczny rozwój stali stosowanych w energetyce na elementy kotłów o parametrach nadkrytycznych stwarza nowe wyzwania spawalnicze. Wprowadzanie coraz to nowych kombinacji dodatków stopowych w celu osiągnięcia jak najlepszych właściwości mechanicznych w tym odporności na pełzanie nie pozostaje bez wpływu na spawalność nowych stali. Każda nowa stal, która zostaje zastosowana na elementy ciśnieniowe kotłów energetycznych musi przejść wiele prób, szczególnie jeśli chodzi o gięcie i spawanie aby możliwe było opracowanie technologii umożliwiających bezproblemowe wykonanie oraz montaż instalacji kotłowych. Przykładem takiej stali jest 7CrMoVTiB10-10 znana również jako T/P24

Doświadczenia przy spawaniu złączy doczołowych rur z nowej generacji stali w gatunku PB2 przeznaczonej dla przemysłu energetycznego

This paper presents a new generation steel PB2 grade assigned for the power industry. In this article the authors present the results of non-destructive (VT, PT, RT) and destructive (tensile test, bending test, hardness measurements, impact strength, macro- and micrograph, fractography) tests. The major objective of the examinations was to verify properties of welded joints made of PB2 steel. Investigation of welded joints made of PB2 steel was performed in Instytut Spawalnictwa in Gliwice and it brings one of the first positive results for this type of steel in the world.W artykule scharakteryzowano stal nowej generacji w gatunku PB2 przeznaczoną dla przemysłu energetycznego. Zaprezentowano wyniki badań nieniszczących (VT, PT, RT) i niszczących (statyczna próba rozciągania, próba zginania, pomiar twardości, pomiar pracy łamania, badania metalograficzne makro- i mikroskopowe) mające na celu sprawdzenie własności połączeń spawanych wykonanych z tego gatunku stali. Badania połączeń spawanych rur ze stali PB2, przeprowadzone w Instytucie Spawalnictwa w Gliwicach są jednymi z pierwszych wyników badań tej stali na świecie

Microstructure and Mechanical Properties of Welded Jointsof Thor 115 Steel

Research was conducted on welded joints of martensitic steel Thor 115 made with two filler materials – CrMo91 and Ni 6082. The scope of the investigations included: non-destructive and destructive testing. The macro- and microstructural investigations revealed correct structure of the weld, without welding imperfections. In the joint welded with Ni 6082, the so-called Nernst’s layers and δ-ferrite grains were visible. The investigations of the analysed joints showed that their properties, i.e. tensile strength and impact strength, were higher than the required minimum, whereas hardness was lower than the maximum value of 350 HV permitted for this group

Quantitative analysis of stability of 9%Cr steel microstructure after long-term ageing

The paper presents the results of research on the microstructure of martensitic X10CrMoVNb9-1 (P91) and X13CrMoCo- VNbNB9-2-1 (PB2) steel subject to long-term ageing at the temperature of 620°C and holding times up to 30 000 hours. The microstructural tests of the examined steel types were performed using a scanning microscope Joel JSM - 6610LV and a transmission electron microscope TITAN 80 - 300. The stability of the microstructure of the investigated steels was analyzed using a quantitative analysis of an image, including measurements of the following: the density of dislocations inside martensite/subgrain laths, the width of martensite laths, and the mean diameter of precipitates. It has been concluded that during long-term ageing, the microaddition of boron in PB2 steel significantly influenced the slowing of the process of degradation of the martensitic steel microstructure, as a result of slowing the process of coagulation of M23C6 carbides and Laves phase. It had a favorable effect on the stabilization of lath microstructure as a result of retardation of the processes of recovery and polygonization of the matrix