Ingrid Kovaříková

Ultrasonic Inspection of Thin Duplex Steel Weld Joints by TOFD

The use of non-destructive inspection techniques in conventional stainless steels is well established. However the non-destructive inspection of duplex and superduplex steels is a big challenge as those steels, being composed of ferrite and austenite, have some particularities. When using ultrasound, for instance, its waves propagate well in ferrite, but suffer strong attenuation, scattering and refraction in austenite. An extended research is proposed on the inspection of duplex steels, especially in welded joints, which presents the worst problems in those steels (incorrect ferrite/austenite balance and precipitation of deleterious phases). The aim of this work was to use the TOFD ultrasonic inspection method for the thin duplex steel weld joint inspection.

Microstructure and Properties of Plasma Arc Welding with Depth Penetration Keyhole SAF 2205 Duplex Stainless Steel

The microstructure and properties of plasma arc welding (PAW) with depth penetration keyhole SAF 2205 duplex stainless steel were examined. High-quality, full-penetration welds were successfully produced in the duplex stainless steel by plasma arc welding (PAW) with depth penetration keyhole. The base material had a microstructure consisting of the ferrite matrix with austenite islands. Ferrite content was held between 60 and 70% throughout the weld. The number grain of the ferrite and austenite phases caused increase in hardness and strength within the stir zone. In the evaluation experiment was used metallographic observation of the integrity and structure of the recast, measuring the proportion of austenite-ferrite in recast, hardness measurements.

Phased Array Ultrasonic Testing of Thin DP Steel Electron Beam Weld Joints

Duplex steels are an important group of materials which are generally used for applications where resistance to corrosion, or high strength and creep resistance at elevated temperatures, are required. They are used extensively in nuclear plant. Although ultrasonic inspection methods have been routinely used in industry for some three decades, it is well known that cast or welded austenitic components can be difficult, or even impossible, to examine ultrasonically. Development of ultrasonic techniques is therefore in progress in several countries to provide improvements which are being sought on safety and economic grounds.The aim of this paper is a brief description of the relevant metallurgical characteristics given before a consideration of the physical properties of the weld metal and the current theoretical models used to describe ultrasound propagation in it. The paper deals with the steps taken to improve the capabilities of ultrasonic inspection and includes a discussion of the problems of flaw location and sizing.

Ultrasonic Inspection of Thin Duplex Steel Welds by Phased Array

The non-destructive inspection of duplex steels is a big challenge, being composed of ferrite and austenite, have some particularities. When using ultrasound, for instance, its waves propagate well in ferrite, but suffer strong attenuation, scattering and refraction in austenite. The aim of this work is to use the Phased Array ultrasonic inspection method for the thin (4 mm) duplex steel weld joint inspection. The experimental sample was made of duplex steel shaped tube with an outer diameter of 44 mm and a wall thickness of 3.8 mm welded with a laser beam. The experiment was necessary to verify attenuation of duplex steel. On the base material and the weld joint were made the artificial defects, in which the adjusted sensitivity of the ultrasonic device was set.The result of the measuring was the defect echo coming from the weld root layer. The length (about 25 mm) can only be estimated due to the inaccurate constant velocity of probe motion along the surface.

Influence of Parameters of Plasma Welding on the Properties of Welded Joints of Duplex Stainless Steels in Mode with Deep Remelting

The paper is focused on the study Influence of parameters of plasma welding on the properties of welded joints of duplex stainless steels in mode with deep remelting. The aim of research is determining a suitable parameters of plasma keyhole welding that will allow the good welding joint, particularly in respect of proper ratio of austenite-ferrite phase without undesirable intermetallic phases.

Research of Cladded Layers Structures Changes Created by Laser Beam Technology Using a Wire Filler Material

The paper is focused on study of cladded layer properties created by laser beam, to abrasive wear resistant. As a basic material was used alloyed tool steel X37CrMoV5, the layers wascreated by laser beam by using a filler materials in the form of wire PZ 6159 and PZ 6168. The aim is research ofcladded layers structures changes, theirmicrohardness changes relative to the basic material and determine the abrasive wear resistance. One of the most important advantages of laser cladding technology is bringing the wire to the exact place of the interaction of a laser beam.

Study of Laser Cladded Layers Structure Applied in Practice

The aim of this paper was the study of laser cladded layers applied in practice from the view of the internal structure of the material changes. In the process of cladding the laser beam was used as the heat source to melt and fuse the cladding alloy LS 30 onto the substrate - steel EN 1.2379.The filler material - wire diameter was 0.4 mm and the maximum height of the coating was 0.3 mm. The basic material was in minimal heat treated, in a very narrow intermediate layer with the character of diffusion joint. The cladded layers were evaluated for resistance to abrasive wear and topography of layers was performed. The proposed technology and the filler material have impact on the topography and roughness of the resulting layers.

Research of Laser Clad Properties with Globular WC in Abrasive Wear Resistance

Laser cladding technology is creating layers with higher wear resistance in compared to conventional technologies of creating surfaces. The aim of this paper was the study of the composite clad properties of globular deposits WC. Required characteristics of certain surfaces can be achieved by a combination of more materials and coatings. Various metal powders can be applied alternately on surface and so to create a specific system layers.