Nanobainitic steels with high Si content are very promising materials due to the very favourable combination of mechanical and functional properties. However, sometimes in order to achieve the required results, it is necessary to further increase the surface's layer hardness. One of the feasible methods of surface hardening is electron beam hardening. In this work, 30 × 20 × 150 mm blocks made of nanobainitic steel were hardened using a defocused oscillating electron beam. Two methods of surface hardening were used – with movement of the sample relative to the heat source and hardening using only beam oscillation. The obtained samples were then subjected to light microscopic and scanning electron microscopic microstructure analysis as well as Vickers hardness testing. The average hardnesses of all hardened samples were in the range of 641–681 HV0.1 which means the surface hardening resulted in a hardness increase in the range of 239–279 HV0.1. The occurrence of similar hardening depths and hardness values in specimens hardened by both methods was an interesting phenomenon that was observed. The amount of energy input needed to achieve similar results was up to 35% less for the method without specimen movement.

Electron beam welding (EBW) is one of the most highly precise methods that is gaining more importance in high-strength structural steel (HSSS) thicker plate application in various vehicles, construction industries, etc. Since it offers particular advantages over arc welding processes like narrow welds, reduced heat-affected zone (HAZ), and low distortion, it inherits lower linear heat input characteristics. The main purpose of this study is to analyze and compare the effect of localized electron beam–post-weld heat treatment (LEB-PWHT) with that of an as-welded EB-welded S960QL joint of a thickness of 12 mm for various joint and HAZ properties. LEB-PWHT can be beneficial in terms of time saving, more local treatment, higher flexibility, energy saving, greater efficiency, increased productivity, etc. In this study, LEB-PWHT was applied to an autogenous EB-welded S960QL joint using a defocused beam. Microstructural characteristics were observed through light optical and scanning electron microscopy (SEM) while mechanical properties, including microhardness, tensile strength, bending, and Charpy V-notch (CVN) impact test, are compared in as-welded and LEB-PWHT joints. The microstructural results showed that the EBW coarse-grain heat-affected zone (CGHAZ) consists of martensite, while the PWHT weld metal contains tempered martensite with carbide precipitates. The fine-grain heat-affected zone (FGHAZ) of EBW exhibits a martensitic and bainitic microstructure, whereas the FGHAZ of the PWHT joint exhibits equiaxed grain with finely dispersed carbides. The hardness decrease after LEB-PWHT in the weld metal and HAZ was approximately 23% and 21%, respectively. An increase in tensile strength (3%) was observed in the LEB-PWHT joints (1082 MPa) compared to the EBW joint (1051 MPa). Both tensile and bending tests demonstrated improved ductility behavior after PWHT. However, the impact test at −40 °C indicated a reduction in toughness in the weld metal of LEB-PWHT (27 J) compared to EBW (63 J).

In this paper, the dataset presents experimentally measured thermal cycles and cooling times (t_8/5) derived during electron beam welded (EBW) of high strength structural steels (HSSSs) in quenched and tempered (Q + T) condition with strength grades ranging from 690 MPa —1300 MPa. The dataset can support the calibration of thermomechanical models, training of AI models for HAZ prediction, and optimization of EBW parameters. These steels are widely used for lightweight structural applications that require high strength, toughness and reliability. The data were recorded for normal EBW and EBW with beam oscillation using K-type thermocouples positioned at 1.55 mm and 2 mm from the weld centerline. The experiments were performed under high vacuum chambers of EBW machine using precisely controlled process parameters. The cooling times were evaluated in the critical 800 -500 °C temperature range (t_8/5) as a function of linear energy and welding parameters. The dataset also includes optical micrographs of the base materials (BM), fusion zones (FZ) and different subzones of the heat-affected zones (HAZ) under various welding conditions. This dataset provides detailed information bridging EBW process variables, plate thickness etc. to measure cooling times in multiphase HSSSs. It provides crucial experimental results for understanding thermal behavior in EB-welded joints which are extremely useful for structural components with sophisticated joint structures. The open access dataset can be reused in various research and development studies like thermo-mechanical modelling, heat-affected zone (HAZ) simulations, and residual stress analyses. It will also support future research focused on improving joint strength, reducing cold cracking susceptibility to maintain structural reliability, and promoting cost-effectiveness in diverse engineering applications.

One of the new areas that requires extensive study of the structure and properties of welded joints is the heat-affected zone (HAZ). This issue is particularly important for new constructions made of aluminium alloys intended for battery housing for powering electric car engines. Modern welding methods, such as EBW and FSW, meet the requirements related to the high precision of the process and the quality of the welded joint itself. This article presents the results of an analysis of the structure and strengthening of the HAZ of chemically modified AlMgSi(Cu) alloys via EBW and FSW. Microstructural observation was performed via SEM for each welded joint to determine the morphology of the precipitates. In the HAZ, β-Mg₂Si, Q-Al,MgCu,Si and α-Al,Fe,Si (Mn,Cu) phases with larger sizes and rounded shapes were visible than they were directly in the weld made via the EBW method. The joints produced by the FSW method were characterised by a wide weld area and an irregular weld line. Analysis of the crystallographic orientation via EBSD and grain orientation spread (GOS) revealed differences in the shape of the grains and the degree of recrystallisation in the weld area between the FSW and EBW methods. The distributions of HB (FSW) hardness and HV (EBW) microhardness measurements revealed a slight decrease in hardening in the HAZ. In joints welded by both methods, the hardness of the welds for alloys with increased copper and chromium contents increased by approximately 5%.