Effect of Residual Elements on Hot-Crack Susceptibility of Austenitic Stainless Steel

Abstract Hot cracking susceptibility and the formation of brittle martensite phase are the main factors that limit the weldability of a dissimilar joint between carbon steel (CS) and austenitic stainless steel (SS). In this study, the self-constraint finger test was used to correlate the welding thermo-mechanical field with the crack susceptibility of a dissimilar weld between the CS ASTM A36 and SS AISI 304L. The finger test allowed to intercalate fingers (portions) of tested materials in the weld samples to produce dissimilar welds. The heat dissipation and the distortion behavior were related to the crack susceptibility, critical weld regions extension and chemical species diffusion. Four samples were welded (two similar welds and two dissimilar welds) using the filler metals ER70S-6 and EC410NiMo. Welds were analyzed through light optical microscopy (LOM) and scanning electron microscopy (SEM) to characterize phases, detect cracks, microstructural changes and element diffusion. A finite element (FE) numerical model was applied to simulate the welding thermo-mechanical field. Additionally, electrochemical tests were carried out to assess the corrosion susceptibility of the dissimilar welds. The observed cracks were produced due to different factors such as residual stress distribution, the formation of brittle and untempered martensitic phase in the fusion zone (FZ) and hot cracking associated with the weld sample distortion behavior. The dilution contributed to the formation of d-ferrite in the FZ, which limited the growth of cold and hot cracks. The decarburization and sensitization were not observed in dissimilar welds due to the low element diffusion.

Download Full-text

Residual Elements Have Significant Effects on the Elevated-Temperature Properties of Austenitic Stainless Steel Welds

Properties of Austenitic Stainless Steels and Their Weld Metals (Influence of Slight Chemistry Variations) ◽

10.1520/stp38352s ◽

2009 ◽

pp. 56-56-12

Author(s):

DP Edmonds ◽

RT King ◽

GM Goodwin

Keyword(s):

Stainless Steel ◽

Elevated Temperature ◽

Austenitic Stainless Steel ◽

Residual Elements ◽

Steel Welds

Download Full-text

Some aspects of the defect structure in an austenitic stainless steel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108714 ◽

1978 ◽

Vol 36 (1) ◽

pp. 314-315

Author(s):

R. Gonzalez ◽

L. Bru

Keyword(s):

Stainless Steel ◽

Austenitic Stainless Steel ◽

Cellular Structures ◽

Total Strain Amplitude ◽

Total Deformation ◽

Density Of Dislocations ◽

Planar Arrays ◽

Stacking Fault Tetrahedra ◽

Distribution Of Dislocations ◽

Very High

The analysis of stacking fault tetrahedra (SFT) in fatigued metals (1,2) is somewhat complicated, due partly to their relatively low density, but principally to the presence of a very high density of dislocations which hides them. In order to overcome this second difficulty, we have used in this work an austenitic stainless steel that deforms in a planar mode and, as expected, examination of the substructure revealed planar arrays of dislocation dipoles rather than the cellular structures which appear both in single and polycrystals of cyclically deformed copper and silver. This more uniform distribution of dislocations allows a better identification of the SFT.The samples were fatigue deformed at the constant total strain amplitude Δε = 0.025 for 5 cycles at three temperatures: 85, 293 and 773 K. One of the samples was tensile strained with a total deformation of 3.5%.

Download Full-text

A TEM microscopical investigation of the magnetic domain structure of a metastable austenitic stainless steel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171213 ◽

1994 ◽

Vol 52 ◽

pp. 696-697

Author(s):

G. Fourlaris ◽

T. Gladman

Keyword(s):

Tensile Strength ◽

Stainless Steel ◽

Austenitic Stainless Steel ◽

Cold Rolling ◽

Solution Treatment ◽

Magnetic Domain ◽

High Strength ◽

Medium Carbon Steel ◽

Magnetic Characteristics ◽

Metastable Austenitic Stainless Steel

Stainless steels have widespread applications due to their good corrosion resistance, but for certain types of large naval constructions, other requirements are imposed such as high strength and toughness , and modified magnetic characteristics.The magnetic characteristics of a 302 type metastable austenitic stainless steel has been assessed after various cold rolling treatments designed to increase strength by strain inducement of martensite. A grade 817M40 low alloy medium carbon steel was used as a reference material.The metastable austenitic stainless steel after solution treatment possesses a fully austenitic microstructure. However its tensile strength , in the solution treated condition , is low.Cold rolling results in the strain induced transformation to α’- martensite in austenitic matrix and enhances the tensile strength. However , α’-martensite is ferromagnetic , and its introduction to an otherwise fully paramagnetic matrix alters the magnetic response of the material. An example of the mixed martensitic-retained austenitic microstructure obtained after the cold rolling experiment is provided in the SEM micrograph of Figure 1.

Download Full-text