A dissimilar autogenous laser welded joint of AISI 430F (X12CrMoS17) martensitic stainless steel and AISI 304 (X5CrNi18-10) austenitic stainless steel was manufactured. The welded joint was examined by non-destructive visual testing and destructive testing by macro- and microscopic examination and hardness measurements. With reference to the ISO 13919-1 standard the welded joint was characterized by C level, due to the gas pores detected. Microscopic observations of AISI 430F steel revealed a mixture of ferrite and carbides with many type II sulfide inclusions. Detailed analysis showed that they were Cr-rich manganese sulfides. AISI 304 steel was characterized by the expected austenitic microstructure with banded δ-ferrite. Martensitic microstructure with fine, globular sulfide inclusions was observed in the weld metal. The hardness in the heat-affected zone was increased in the martensitic steel in relation to the base metal and decreased in the austenitic steel. The hardness range in the weld metal, caused by chemical inhomogeneity, was 184–416 HV0.3.

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The aim of the present study was to characterize the repair weld of serviced (aged) solid-solution Ni-Cr-Fe-Mo alloy: Hastelloy X. The repair welding of a gas turbine part was carried out using Gas Tungsten Arc Welding (GTAW), the same process as for new parts. Light microscopy, scanning electron microscopy, transmission electron microscopy, microhardness measurements were the techniques used to determine the post repair condition of the alloy. Compared to the solution state, an increased amount of M 6 C carbide was detected, but M 23 C 6 carbides, sigma and mu phases were not. The aged condition corresponds to higher hardness, but without brittle regions that could initiate cracking.

This paper defines the wear process of rollers made of 20Cr4. Rollers with a diameter of 1000 mm were installed in a roller press used for the production of drop-shaped briquettes and the copper concentrate was briquetted for 1100 h. Three-dimensional (3D) geometry analysis, metallographic analysis, macroscopy, scanning electron microscopy, as well as hardness measurements were performed. It was observed that the working surface was non-uniformly worn. The smallest wear affects the molding cavities situated on the outermost edges of the ring. The wear increases as the center of the ring is approximated, and it reaches its maximum at the middle of the ring. The molding cavities also wear asymmetrically. For the shape considered in this study, the lower part of a cavity is subject to a higher wear rate. We found that the material of the working ring was carburized, but its hardness was significantly lower than required. The roller ring microstructure changes depended on the distance from the cavity’s face. An investigation of the wear mechanisms showed different types of abrasive wear, corrosive processes, and plastic deformation. The exact type and course of wear were described, depending on the location on the working surface.

Fracture evaluation of welded joints in high-strength steels, with bainitic and martensitic structures, is presented and cracking mechanisms discussed. Hot cracks or microcracks formed during welding are further expanded as cold cracks on cooling. The cause of cracking is shown to be low temperature of weld solidification and deformation-induced contraction. Hydrogen can also be an important factor in this cracking.

Właściwości połączeń spawanych stali 7CrMoVtiB10-10 (t24) po obróbce cieplnej the properties of joints of 7crMoVtiB10-10 (t24) steel after heat treatment Mgr inż. Krzysztof Pańcikiewicz, prof. dr hab. inż. Edmund Tasak -Akademia Górniczo-Hutnicza, Kraków, mgr inż. Sławomir Kwiecień -polimex Mostostal Zakład ZRE, Kraków. StreszczenieW artykule przedstawiono wyniki oceny twardości i pracy łamania spoin po obróbce cieplnej złączy spawanych żarowytrzymałej stali niskostopowej T24 (7CrMo--VTiB10-10). Wykazano, że otrzymanie jednocześnie wymaganych właściwości plastycznych i twardości jest możliwe jedynie po wyżarzaniu w temperaturze co najmniej 700ºC. Podjęto również próbę wyjaśnienia przyczyn występowania niezadowalającej twardości złączy i udarności spoin po obróbce cieplnej w stosunkowo do niskiej temperaturze wyżarzania.

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