Austenitic stainless steel bismuth-free flux-cored wires for high-temperature applications

Abstract

Since the 1970s, bismuth is widely used as an auxiliary ingredient in stainless steel flux-cored wires to improve slag detachability. But, for components subject to post-weld heat treatment (PWHT) and/or applications at high temperature, bismuth has been confirmed to have a negative effect on weld metal ductility. It has been suggested that this is due to grain boundary bismuth segregation, and it has been debated whether it is as bismuth or as bismuth oxide Bi 2 O 3 . There are also reports on cracks found in weldments after service at elevated temperatures. This has affected the specifications, and API RP 582 has included a maximum bismuth content of 20 ppm in the weld deposit when welding with austenitic stainless steel flux-cored wires for applications above 538°C, including PWHT. This demand required development of a range of flux-cored wires intended for overlay welding (cladding) of creepresistant steels and joining stainless steels for hightemperature applications. Standard E347, E309L and E308H wires have here been compared with bismuthfree versions in as-welded condition and after PWHT. All-weld metal has been subject to mechanical, hot ductility and Varestraint testing. Results show that bismuthfree wires have higher ductility, and this was confirmed also when welding in single V-butt weld joints. Electron microprobe analysis (EPMA) modified for high precision mapping is used to illustrate that bismuth has a particle-like distribution without any clear relation to oxygen.

Genotoxicity and inflammatory potential of stainless steel welding fume particles: an in vitro study on standard vs Cr(VI)-reduced flux-cored wires and the role of released metals

“…In agreement with the EDS findings, the Mn content of F1 was below the quantification limit. Bi was present in its trivalent form [probably from added Bi 2 O 3 in the flux powder (Westin et al 2016 )], Figure S8. The Si peak position indicated the presence of both silica and organic silicon, Figure S9.…”

Nonlinear fatigue life prediction model based on the theory of the S‐N fatigue damage envelope

“…[46][47][48] Meanwhile, A387 GR 22 (10CrMo9-10) is commonly used in seamless pipes for steam conditions reaching high temperatures, such as pressurized parts of boilers powered by fossil fuels and heat recovery system generators. 49,50 A336 GR 5 can also be found to be applicable in the same domain. 51 The specimens were all fatigued under stress controlled fully reversed (R ¼ À1) tension compression loading, at 20 Hz in room temperature (21 C).…”