Evolution of Welding Residual Stresses within Cladding and Substrate during Electroslag Strip Cladding

Abstract

Hydrogenation reactors are important oil-refining equipment that operate in high-temperature and high-pressure hydrogen environments and are commonly composed of 2.25Cr–1Mo–0.25V steel. For a hydrogenation reactor with a plate-welding structure, the processes and effects of welding residual stress (WRS) are very complicated due to the complexity of the welding structure. These complex welding residual stress distributions affect the service life of the equipment. This study investigates the evolution of welding residual stress during weld-overlay cladding for hydrogenation reactors using the finite element method (FEM). A blind hole method is applied to verify the proposed model. Unlike the classical model, WRS distribution in a cladding/substrate system in this study was found to be divided into three regions: the cladding layer, the stress-affected layer (SAL), and the substrate in this study. The SAL is defined as region coupling affected by the stresses of the cladding layer and substrate at the same time. The evolution of residual stress in these three regions was thoroughly analyzed in three steps with respect to the plastic-strain state of the SAL. Residual stress was rapidly generated in Stage 1, reaching about −440 MPa compression stress in the SAL region at the end of this stage after 2.5 s. After cooling for 154 s, at the end of Stage 2, the WRS distribution was fundamentally shaped except for in the cladding layer. The interface between the cladding layer and substrate is the most heavily damaged region due to the severe stress gradient and drastic change in WRS during the welding process. The effects of substrate thickness and preheat temperature were evaluated. The final WRS in the cladding layer first increased with the increase in substrate thickness, and then started to decline when substrate thickness reached a large-enough value. WRS magnitudes in the substrate and SAL decreased with the increase in preheat temperature and substrate thickness. Compressive WRS in the cladding layer, on the other hand, increased with the increase in preheat temperature.

Effects of normalizing temperature on microstructure and high-temperature properties of 2.25Cr-1Mo-0.25V bainitic steel

“…In the oil-refining sector, hydrogenation reactors must run for extended periods of time under hightemperature, high-pressure, and hydrogen conditions [1]. Low alloy 2.25Cr-1Mo-0.25V steel, the material of hydrogenation reactors, requires outstanding raised temperature performance and resistance to oxidation for safe operation [2][3][4]. The size and cross-section of pressure vessels can also be expanded to achieve improved processing efficiency, due to an increase in energy consumption [5].…”

Impact of Cladding Technology on Residual Stresses within the Renovation of High Pressure Die Casting Molds

“…The analysis of the residual stresses by hole drilling method in explosive welding is discussed in [22]. The determination of the residual stresses using the electroslag strip cladding method is discussed in [23]. Finally, the combination of the determination of residual stresses by finite element method and the hole drilling method is described in [24].…”