The structure of the superheated region of the heat-affected zone of the welded joint in heat-resisting pearlitic steels

Investigations were carried out into the formation of Widmanstatten ferrite in the structure of the section of incomplete recrystallization of the heat-affected zone of welded joints in heat-resisting pearlitic steels in the conditions of heating during welding.     

Improving materials and welding technology for dissimilar welded joints in austenitic and pearlitic steels

The first layer of the deposit on the edges of low-alloy steels in producing welded joints with 08Cr18Ni10Ti steel is made using materials based on 02Cr24Ni13 composition (TsL-25L electrodes, welding wire SV-02Cr24Ni13) producing the deposited metal with a reduced carbon content and the required content of the ferritic phase (2–5%). Welding with these materials results in the required parameters of technological properties in welding and efficiency of the austenitic–ferritic deposited metal:

• resistance to solidification cracking;

• preventing the formation of a structure containing very hard brittle compounds;

• preventing the formation of the sigma phase and, correspondingly, embrittlement in tempering;

• the mechanical properties and fatigue strength satisfy the requirements of PNAE G-7-002–86.

Technical documents for the production of these welding materials have been compiled.     

Effect of the structure of weld metal on the pitting susceptibility of welded joints of ferritic-austenitic steel

The structure of welded joints of tubes from ferritic-austenitic steel 02Kh22N5AM3 is studied by methods of metallographic, x-ray diffraction, and electron microscopic analyses. Corrosion properties of welded joints are determined in pitting tests. The results of the study are used for developing a mode of welding and heat treatment that increases substantially the corrosion resistance of the weld metal. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 32–35, July, 2006.     

Effects of artificial defects in weld metal on characteristics of welded joints

The system for automatic design of welding technology, described in the article, can be used to improve the quality of welded joints, increase labour productivity, reduce material losses, increase technological discipline and shorten the time required for the technological preparation of production.     

低相变点焊缝金属接头的焊接残余变形

试验中低相变点焊缝金属的固态相变温度在190℃左右，由于焊缝金属相变体积膨胀使其焊接接头的焊接残余变形降低。利用低相变点焊条LTrE和普通焊条E5015通过V形坡口对接接头和半V形坡口T形接头的角变形以及平板堆焊试验，探讨了焊缝金属固态相变对焊接变形的影响。两种接头角变形试验结果表明，LTTE焊条试件具有较小的角变形，其角变形分别为E5015焊条试件角变形的69．1％和64．3％；LTTE焊条平板堆焊试件出现反变形，在该试验条件下反变形挠度为-1．9mm，而E5015焊条试件的正变形挠度为2mm。这些试验结果为减小和控制焊接残余变形提供了一条有效的方法。     

Structure and mechanism of formation of dissimilar welded joints in nuclear power plant made of austenitic and pearlitic steels

The structure and mechanism of the formation of welded joints in pearlitic and austenitic steels in power engineering structures are analyzed. The results of investigations of the crystal structure of metals and metallurgical processes taking place in the welding zone are presented. Recommendations are given for improving the welding technology and welding materials, and the chemical composition of the materials used in these applications is determined more accurately.     

Weldability and high temperature performance of welded joints of heat-resisting alloys

The applications of various heat resisting alloys applications depend upon the service temperature and the environment in which they are employed; austenitic stainless steels are employed mainly in the temperature region of approximately 850-950 K and Fe-base, Co-base and Ni-base superalloys are employed for high-temperature use at more than approximately 950 K. Problems concerning the integrity of weld procedures and high-temperature performance of weld zones should be considered for the application of these heat-resisting alloys to welded structures. In fact, most heat resisting alloys have poor weldability compared with carbon and low-alloy steels and are subject to problems such as cracking during welding. Furthermore, there are many instances of deteriorating high-temperature performance of the weld zone due to changes in the microstructure which accompany welding. On the other hand, heat-resisting alloys are employed in severe high-temperature environments and it is highly possible that there will be an occurrence of fissures and deterioration due to deformation, creep damage, oxidation and carburising. There are many cases where materials which have been in service for extended periods have increased weld crack susceptibility. Repair welding of these requires further attention to be given to the possibility of weld cracks.     

Mechanical properties and structure of welded joints in a low carbon structure of pearlitic steel produced by various welding methods

Abstract

This article reports on the present use of resistance welding in the manufacture of cardiac pacemakers as well as on what possible general conclusions can be drawn and on a number of worthwhile improvements or supplementary additions that can be made to the type FP 5/20 welding machine.     

Fatigue strength of welded joints in austenitic Cr-Ni steels

Abstract

High quality corrosion resistant Cr-Ni steels are used in many branches of industry. Constructors are faced with the problem of correctly dimensioning statically and dynamically loaded parts, but have little data available for dynamically loaded welded constructions of high alloy austenitic steels. To close this gap fatigue strength tests were carried out on three different steels and five different welded joints.