| 1. |
- Hedström, Peter, et al.
(författare)
-
Load partitioning between single bulk grains in a two-phase duplex stainless steel during tensile loading
- 2010
-
Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 58:2, s. 734-744
-
Tidskriftsartikel (refereegranskat)abstract
- The lattice strain tensor evolution for single bulk grains of austenite and ferrite in a duplex stainless steel during tensile loading to 0.02 applied strain has been investigated using in situ high-energy X-ray measurements and finite-element modeling. Single-grain X-ray diffraction lattice strain data for the eight austenite and seven ferrite grains measured show a large variation of residual lattice strains, which evolves upon deformation to the point where some grains with comparable crystallographic orientations have lattice strains different by 1.5 x 10(-3), corresponding to a stress of similar to 300 MPa. The finite-element simulations of the 15 measured grains in three different spatial arrangements confirmed the complex deformation constraint and importance of local grain environment.
|
|
| 2. |
- Huang, Shuo, et al.
(författare)
-
Thermal Expansion, Elastic and Magnetic Properties of FeCoNiCu-Based High-Entropy Alloys Using First-Principle Theory
- 2017
-
Ingår i: JOM. - : Springer. - 1047-4838 .- 1543-1851. ; 69:11, s. 2107-2112
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of V, Cr, and Mn on the magnetic, elastic, and thermal properties of FeCoNiCu high-entropy alloy are studied by using the exact muffin-tin orbitals method in combination with the coherent potential approximation. The calculated lattice parameters and Curie temperatures in the face-centered-cubic structure are in line with the available experimental and theoretical data. A significant change in the magnetic behavior is revealed when adding equimolar V, Cr, and Mn to the host composition. The three independent single-crystal elastic constants are computed using a finite strain technique, and the polycrystalline elasticity parameters including shear modulus, Young's modulus, Pugh ratio, Poisson's ratio, and elastic anisotropy are derived and discussed. The effects of temperature on the structural parameters are determined by making use of the Debye-Gruneisen model. It is found that FeCoNiCuCr possesses a slightly larger thermal expansion coefficient than do the other alloys considered here.
|
|
| 3. |
- Kohne, Thomas, 1990-, et al.
(författare)
-
Evolution of Martensite Tetragonality in High-Carbon Steels Revealed by In Situ High-Energy X-Ray Diffraction
- 2023
-
Ingår i: Metallurgical and Materials Transactions. A. - : Springer. - 1073-5623 .- 1543-1940. ; 54:4, s. 1083-1100
-
Tidskriftsartikel (refereegranskat)abstract
- The martensitic transformation was studied by in situ and ex situ experiments in two high-carbon, 0.54 and 0.74 wt pct C, steels applying three different cooling rates, 15 °C/s, 5 °C/s, and 0.5 °C/s, in the temperature range around Ms, to improve the understanding of the evolution of martensite tetragonality c/a and phase fraction formed during the transformation. The combination of in situ high-energy X-ray diffraction during controlled cooling and spatially resolved tetragonality c/a determination by electron backscatter diffraction pattern matching was used to study the transformation behavior. The cooling rate and the different Ms for the steels had a clear impact on the martensitic transformation with a decrease in average tetragonality due to stronger autotempering for a decreasing cooling rate and higher Ms. A slower cooling rate also resulted in a lower fraction of martensite at room temperature, but with an increase in fraction of autotempered martensite. Additionally, a heterogeneous distribution of martensite tetragonality was observed for all cooling rates. © 2023, The Author(s).
|
|
| 4. |
- Mellin, Pelle, 1985-, et al.
(författare)
-
Nano-sized by-products from metal 3D printing, composite manufacturing and fabric production
- 2016
-
Ingår i: Journal of Cleaner Production. - Sweden : Elsevier. - 0959-6526 .- 1879-1786. ; 139, s. 1224-1233
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, the health and environmental perspective of nano-materials has gained attention. Most previous work focused on Engineered Nanoparticles (ENP). This paper examines some recently introduced production routes in terms of generated nano-sized by-products. A discussion on the hazards of emitting such particles and fibers is included. Fine by-products were found in recycled metal powder after 3D printing by Selective Laser Melting (SLM). The process somehow generated small round metal particles (~1e2 mm) that are possibly carcinogenic and respirable, but not small enough to enter by skin-absorption. With preventive measures like closed handling and masks, any health related effects can be prevented. The composite manufacturing in particular generated ceramic and carbonaceous particles that are very small and respirable but do not appear to be intrinsically toxic. The smallest features in agglomerates were about 30 nm. Small particles and fibers that were not attached in agglomerates were found in a wide range of sizes, from 1 μm and upwards. Preventive measures like closed handling and masks are strongly recommended. In contrast, the more traditional production route of fabric production is investigated. Here, brushing residue and recycled wool from fabric production contained few nano-sized by-products.
|
|
| 5. |
- Weidow, J., et al.
(författare)
-
Impact of crystal defects on the grain growth of cemented carbides
- 2018
-
Ingår i: International journal of refractory metals & hard materials. - : Elsevier Ltd. - 0263-4368 .- 2213-3917. ; 72, s. 199-202
-
Tidskriftsartikel (refereegranskat)abstract
- Two different WC-Co powder mixtures were produced through a 200 h milling process. One of these mixtures were heat treated with the aim to remove the crystal defects from the WC grains. Image analysis showed that the two powders had the same average WC grain size and grain size distributions. X-ray diffraction showed much more narrow peaks for the material produced from the heat treated powder thus interpreted to have much less crystal defects. The powder mixtures were used to produce cemented carbides. Image analyses showed a clear difference for the WC grain sizes where the material produced from the heat treated powder had a significantly smaller mean WC grain size. It is therefore concluded that the crystal defects are of importance and facilitate WC grain growth during sintering.
|
|
| 6. |
- al-Emrani, Mohammad, 1967, et al.
(författare)
-
Fatigue improvement of welded bridge details in stainless steel using high-frequency mechanical impact treatment
- 2018
-
Ingår i: Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges - Proceedings of the 9th International Conference on Bridge Maintenance, Safety and Management, IABMAS 2018. - : CRC PRESS-TAYLOR & FRANCIS GROUP. ; , s. 446-451, s. 446-451
-
Konferensbidrag (refereegranskat)abstract
- This paper reports the results from fatigue testing on welded non-load-carrying transverse attachments made of C-Mn (S460) and stainless (LDX2101) steels. The tests are done on 40 mm thick specimens in as-welded and HFMI-treated specimens. Measurements on weld toe radius and weld residual stresses are also reported. The results show that the improvement of fatigue strength that can be achieved by HFMItreatment on welded LDX2101 steel is similar to what is obtained for equivalent C-Mn steels. Also in the aswelded condition do these two types of steel show similar fatigue strength. HFMI-treatment gives more than 5 steps increase in fatigue strength for both steels, which is higher than what specified, for example by the recommendations of the International Institute of Welding.
|
|
| 7. |
- Aldén, R., et al.
(författare)
-
Robustness of the HFMI techniques and the effect of weld quality on the fatigue life improvement of welded joints
- 2020
-
Ingår i: Welding in the World. - : Springer Science and Business Media Deutschland GmbH. - 0043-2288 .- 1878-6669. ; 64:11, s. 1947-1956
-
Tidskriftsartikel (refereegranskat)abstract
- Robustness of HFMI treatment in different weld qualities according to ISO 5817 was studied, and fatigue testing of the treated samples was carried out in order to investigate the effect of the weld quality prior treatment. The results show that HFMI-treated welds with weld quality level D shows fatigue life improvements that fall within the IIW recommendations for HFMI. No significant influence from the HFMI operator or HFMI equipment on the fatigue life was found. However, the scatter in fatigue testing results varied with HFMI operator and indicated that different HFMI operators could produce consistent treatment results. A considerable effect on fatigue life from HFMI tool radius was found, where the 2-mm tool radius showed considerably greater fatigue life compared with the 1.5-mm tool radius. According to IIW (Marquis and Barsoum 2016), for steel grade SY = 700 MPa, the fatigue strength recommendation is FAT 160 (m = 5) for transverse stiffener–welded joints with as-welded quality B according to ISO 5817 (ISO/TC 44/SC 10 2011), prior to treatment. It can be observed in the current study that fatigue-tested HFMI-treated welded joints, welded with weld quality D, are in good agreement with the IIW recommendations.
|
|
| 8. |
- Bjurman, Martin, et al.
(författare)
-
Microstructural evolution of welded stainless steels on integrated effect of thermal aging and low flux irradiation
- 2019
-
Ingår i: Minerals, Metals and Materials Series. - : Springer International Publishing. - 2367-1696 .- 2367-1181. ; Part F11, s. 703-710
-
Konferensbidrag (refereegranskat)abstract
- The combined effect of thermal aging and irradiation on cast and welded stainless steel solidification structures is not sufficiently investigated. From theory and consecutive aging and irradiation experiments, the effect of simultaneous low rate irradiation and thermal aging is expected to accelerate and modify the aging processes of the ferrite phase. Here, a detailed analysis of long-term aged material at very low fast neutron flux at LWR operating temperatures using Atom Probe Tomography is presented. Samples of weld material from various positions in the core barrel of the Zorita PWR are examined. The welds have been exposed to 280–285 °C for 38 years at three different neutron fluxes between 1 × 10 −5 and 7 × 10 −7 dpa/h to a total dose of 0.15–2 dpa. The aging of the ferrite phase occurs by spinodal decomposition, clustering and precipitation of e.g. G-phase. These phenomena are characterized and quantitatively analyzed in order to understand the effect of flux in combination with thermal aging.
|
|
| 9. |
- Boåsen, Magnus, et al.
(författare)
-
Analysis of thermal embrittlement of a low alloy steel weldment using fracture toughness and microstructural investigations
- 2022
-
Ingår i: Engineering Fracture Mechanics. - : Elsevier BV. - 0013-7944 .- 1873-7315. ; 262
-
Tidskriftsartikel (refereegranskat)abstract
- A thermally aged low alloy steel weld metal is investigated in terms of its fracture toughness and microstructural evolution and compared to a reference. The main purpose of the study is to investigate the effects of embrittlement due to thermal ageing on the brittle fracture toughness, and its effects on the influence of loss of crack tip constraint. The comparison of the investigated materials has been made at temperatures that give the same median fracture toughness of the high constraint specimens, ensuring comparability of the low constraint specimens. Ageing appears to enable brittle fracture initiation from grain boundaries besides initiation from second phase particles, making the fracture toughness distribution bimodal. Consequently, this appears to reduce the facture toughness of the low constraint specimens of the aged material as compared to the reference material. The microstructure is investigated at the nano scale using atom probe tomography where nanometer sized Ni-Mn-rich clusters, precipitated during ageing, are found primarily situated on dislocation lines.
|
|
| 10. |
- Edgren, Martin, et al.
(författare)
-
Evaluation of HFMI as a Life Extension Technique for Welded Bridge Details
- 2019
-
Ingår i: Procedia Structural Integrity. - : Elsevier BV. - 2452-3216. ; 19, s. 73-80
-
Konferensbidrag (refereegranskat)abstract
- Published by Elsevier B.V. In this current study, HFMI technique is used to study the possibility to extend the fatigue life of pre-fatigued flange gusset welds typically found in girder bridges. The results from the study are also compared with results found in the literature for other more conventional techniques for retrofitting, e.g. cut-outs. The study also aims to investigate if the IIW HFMI recommendations could be applied for existing steel structures and that equal fatigue strength improvement could be claimed for prefatigued structures. Furthermore, new recommendations for structural hot spot stress type B are suggested for HFMI treated welds, applicable to flange guest welds. The results indicate that the HFMI could be used for welded bridge details rehabilitation as a competing technology with conventional cut-out. Furthermore, the results indicate that the IIW recommendations for HFMI fatigue strength improvement could also be applied for pre-fatigued welded details. © 2019 The Authors.
|
|
