Features of Acoustic Emission in Tensile Testing of Dissimilar Welded Joints of Pearlitic and Austenitic Steels

Abstract

This paper presents a study of acoustic emission (AE) during the deformation of dissimilar welded joints of austenitic steel to pearlitic steel. One of the specific problems in these welded joints is the presence of decarburized and carbide diffusion interlayers, which intensively increase in width during long-term high-temperature operation. The presence of wide interlayers negatively affects the mechanical properties of welded joints. Moreover, welded defects are difficult to diagnose in welded joints containing interlayers: due to the high structural heterogeneity, interlayers create structural noises that can hinder the detection of defects such as cracks, pores, or a lack of penetration. The AE method may become a complex decision for diagnosing dissimilar welded joints due to applicability to the testing of heterogenic materials with a complex microstructure. Specimens cut from dissimilar welded joints of austenitic steel to pearlitic steel were tested by tension to rupture, with parallel AE data registration. According to the research results, the characteristic features of the AE were revealed for specimens containing defects in the form of lack of penetration as well as for specimens with diffusion interlayers. The results obtained show that the AE method can be used to test both typical welding defects and diffusion interlayers in welded joints of steels of different structural classes.

Assessment of the Structural State of Dissimilar Welded Joints by the Acoustic Emission Method

“…Moreover, an additional maximum of the AE hit rate appeared in the specimen with interlayers under static tension at such loads. In addition, such an AE waveform was detected during tension of dissimilar welded joints with diffusion interlayers in [22].…”

“…It is advisable to start with considering patterns of AE data recorded under static loading (described in detail in [22]) to gain deep knowledge and understanding of AE data parameters under cyclic loading. Figure 4 shows the AE data obtained under static tension of a specimen without interlayers.…”

“…We studied the dissimilar welded joints of 12Kh18N10T austenitic steel to 09G2S pearlitic steel. In [22], AE monitoring under static tension of the dissimilar welded joint is investigated by the authors. Therefore, this research is devoted to the study of AE technique application under cyclic loading of dissimilar welded joints.…”

Intelligent Testing and Analysis of Dissimilar Steel Welds for Industrial Throttle Flowmeter

“…Danielewski et al [8] conducted metallographic analysis of the weld and found that in stainless steel, the heat-afected zone was very narrow, and the growth of austenite grains was not observed, while the slender grains of ferrite formed a discontinuous network around the austenite grain. Another problem with dissimilar steel welds between austenitic steel and pearlitic steel is the presence of decarburization and carbide interlayers, which have an adverse efect on the mechanical properties of the welding seam [9]. Nikulina et al [10] studied the fash butt welding of high-carbon pearlitic steel and chromium-nickel austenitic steel, and the results showed that layered pearlite colonies containing chromium and nickel and thin austenite interlayers were formed in the weld zone.…”

“…Hempel [19] conducted an in-depth study on the residual stress state of dissimilar steel welds using X-ray and neutron difraction and confrmed that the residual stress on the surface of austenitic tubes during sample preparation was greatly afected by the machining technology. Barat et al [9] experimentally confrmed that the acoustic emission method can be used to detect both typical welding defects in welded joints of diferent structural grades of steel as well as difusion interlayers. Lyubimova et al [20] proposed that the combination of X-ray fuorescence analysis, X-ray difraction, and microhardness determination with traditional inspection methods (visual or ultrasonic inspection [21], etc.)…”