MOBILE AND STATIONARY SYSTEMS FOR ORGANIC PIGS – ANIMAL BEHAVIOUR IN OUTDOOR PENS

The production of organic pork in Sweden has increased. For several years, however, demand has been greater than production. An important factor contributing to the limited production is a lack of knowledge and experience of outdoor pig systems, since they are uncommon in Sweden. This study compared the behaviour of fattening pigs in two different organic produc¬tion systems, with the main focus on excretory behaviour. In both the mobile and the stationary system there was an uneven distribution of manure and urine in the pens. In the mobile system, the hotspots were in the hut area and in part of the drinking area, while in the stationary system, the concrete pad as well as the wallowing area and the first section of the transporta¬tion area seemed to be the hotspots. Furthermore, the pigs avoided defecating around the feeding troughs and lying area in the mobile system. A more uniform distri¬bution of nutrients can possibly be obtained by manipulating the excretory behaviour of the pigs, e.g. by regularly shifting the positions of the feeders and huts

Elemental distribution in a decommissioned high Ni and Mn reactor pressure vessel weld metal from a boiling water reactor

In this paper, weld metal from unique material of a decommissioned boiling water reactor pressure vessel is investigated. The reactor was in operation for 23 effective full power years. The elemental distribution of Ni, Mn, Si and Cu in the material is analysed using atom probe tomography. There are no well-defined clusters of these elements in the weld metal. However, some clustering tendencies of Ni was found, and these are interpreted as a high number density of small features. Cu atoms were found to statistically be closer to Ni atoms than in a fully random solid solution. The impact of the non-random elemental distribution on mechanical properties is judged to be limited

Effects of Irradiation and Thermal Ageing on the Nanoscale Chemistry of Steel Welds

Structural materials of nuclear power plants degrade during operation due to thermal ageing and irradiation from the reactor core. Effects on the materials are an increase in hardness and tensile strength, and a decrease in ductility and fracture toughness, i. e. embrittlement. The degradation of the mechanical properties stems from changes in the microstructure. In this thesis, the effects of thermal ageing and irradiation on the nanoscale chemistry has been studied using atom probe tomography (APT).\ua0During irradiation, nanometre sized clusters are formed in the reactor pressure vessel (RPV) welds. As the RPV is a life-limiting part of a nuclear power plant, neutron irradiation with high flux is attractive for accelerated studies. Here, the effect of high flux is found to result in a higher number density of smaller NiMnSi-rich clusters for the high Ni and Mn - low Cu welds from Ringhals R4, resulting in similar hardening compared to surveillance material. It is also found that there are some stable matrix defects formed in the high flux material, contributing to the embrittlement. The cluster evolution showed no signs of late blooming phases (an accelerated degradation at high fluences). Furthermore, thermal ageing during operation for 28 years of a weld from the former Ringhals R4 pressurizer with similar composition is found to result in\ua0 clusters forming mainly on dislocations, hardening the weld metal.\ua0In ferrite with higher Cr-content, such as the ferritic parts of the mainly austenitic welds from the core barrel of the decommissioned Spanish reactor Jos\ue9 Cabrera, spinodal decomposition occurs as well as G-phase (Ni16Si7Mn6) precipitation. Weld metals irradiated up to 2 dpa are compared with thermally aged welds, confirming that the irradiation is considerably contributing to the changes in the microstructure. After 0.15 dpa, the spinodal decomposition was well developed, and the Cr concentration in the ferrite was found to influence the wavelength more than the difference in irradiation (0.15 to 2 dpa). The G-phase precipitates were more well-developed after 1 dpa neutron irradiation, but no difference could be distinguished between the material irradiated to 1 and 2 dpa

In situ tempering of martensite during laser powder bed fusion of Fe-0.45C steel

During laser powder bed fusion (L-PBF), materials experience cyclic re-heating as new layers are deposited, inducing an in situ tempering effect. In this study, the effect of this phenomenon on the tempering of martensite during L-PBF was examined for Fe-0.45C steel. Detailed scanning electron microscopy, transmission electron microscopy, atom probe tomography, and hardness measurements indicated that martensite was initially in a quenched-like state after layer solidification, with carbon atoms segregating to dislocations and to martensite lath boundaries. Subsequent tempering of this quenched-like martensite was the result of two in situ phenomena: (i) micro-tempering within the heat affected zone and (ii) macro-tempering due to heat conduction and subsequent heat accumulation. Hardness measurements showed that although both influenced martensite tempering, micro-tempering had the most significant effect, as it reduced martensite hardness by up to ∼380 HV. This reduction was due to the precipitation of nano-sized Fe3C carbides at the previously carbon-enriched boundaries. Lastly, the magnitude of in situ tempering was found to be related to the energy input, where increasing the volumetric energy density from 60 to 190 J/mm3 reduced martensite hardness by ∼100 HV. These findings outline the stages of martensite tempering during L-PBF and indicate that the level of tempering can be adjusted by tailoring the processing parameters

Integrated effect of thermal ageing and low flux irradiation on microstructural evolution of the ferrite of welded austenitic stainless steels

With the purpose to quantify microstructural changes with respect to ageing degradation, the microstructure of aged type 308 stainless steel welds with a ferrite content of 5-7% has been analysed using atom probe tomography. The weld metal of the core barrel of a decommissioned light water reactor, irradiated during operation of the reactor to 0.1 dpa, 1 dpa and 2 dpa at 280-285\ub0C (231,000 h), are compared to two similar thermally aged welds. In the ferrite of the irradiated welds, there is spinodal decomposition into Cr-rich α’ and Fe-rich α, with a similar degree of decomposition for all investigated doses, amplitudes of 21-26% and wavelengths between 6 and 9 nm. The ferrite of the thermally aged material showed evidence of decomposition when aged at 325\ub0C (an amplitude of 13-14% and wavelength of 5 nm), but not when aged at 291\ub0C, thus the irradiation significantly increases the rate of spinodal decomposition. There is G-phase (Ni Si Mn ) precipitation in the ferrite of all the weld metals except the one that was thermally aged at the lowest temperature. After irradiation to 1 and 2 dpa, the G-phase is considerably more well developed than after 0.1 dpa or thermal ageing

Organic Pig Production in Europe - Health Management in Common Organic Pig Farming

Organic farmers in Europe have developed different housing systems for pigs based on the availability of land, soil characteristics, climate, tradition and national organic certification schemes. This guide gives an overview of the typical housing systems used for pigs in organic farming. It lists advantages and disadvantages of the different systems and provides relevant recommendations to farmers for health managment

The Nanostructure of the Oxide Formed on Fe-10Cr-4Al Exposed in Liquid Pb

An Fe-10Cr-4Al alloy containing reactive elements developed for application in high-temperature liquid lead environments was analyzed after exposure in 600 and 750\ub0C lead with dissolved oxygen for 1,000-2,000 h. Atom probe tomography, transmission electron microscopy, and X-ray scattering were all used to study the protective oxide formed on the surface. Exposure at 750\ub0C resulted in a 2-μm thick oxide, whereas the 600\ub0C exposure resulted in a 100-nm thick oxide. Both oxides were layered, with an Fe-Al spinel on top, and an alumina layer toward the metal. In the 600\ub0C exposed material, there was a Cr-rich oxide layer between the spinel and the alumina. Metallic lead particles were found in the inner and middle parts of the oxide, related to pores. The combination of the experimental techniques, focusing on atom probe tomography, and the interpretations that can be done, are discussed in detail

Atom probe tomography characterisation of powder forged connecting rods alloyed with vanadium and copper

The precipitation of V and Cu in the powder forged connecting rods of Fe-V-Cu-C alloy, were studied by atom probe tomography (APT). The purpose of alloying with V was to further improve the mechanical properties of the existing powder forged materials based on Fe-Cu-C. In this study, materials tested at room temperature and 120 degrees C were investigated. It was found that Cu was unevenly distributed on a micrometer scale. The local Cu content affected the Cu precipitation; a higher Cu content resulted in a higher volume fraction of precipitates. The V was found to form very small nitrides. The N presumably originates from the sintering process. The vanadium nitrides act as nucleation points for the Cu precipitates during cooling of the material during fabrication. APT analysis of the deformed material close to the fracture surface of the tensile test samples showed a similar volume fraction of Cu precipitates, but statistical analysis of the data indicates that both Cu and VN precipitates are more diffuse than in the undeformed material

Piglet mortality in organic herds

Productive performance of organic pig farms is lower compared to conventional farms, but only very few data exist. Better knowledge of the productivity of organic herds regarding litter size at birth, piglet losses around birth and during lactation, as well as housing and management conditions should help to identify critical points and hence to improve the situation. Therefore, a research project was initiated in 6 EU countries (Corepig). As part of this, farmers recorded production data during 3-11 months starting between January and July 2008. Farmers were asked to record the numbers of piglets born dead, born alive as well as the number of piglets at weaning. Taking into account the quality of the records and setting a threshold of ≥ 10 litters/farm, data from 38 farms in 4 countries (France: 14, Germany: 12, Austria: 7, Sweden: 5) were analyzed (mean: 69, 10 to 713 litters/farm). Most farmers were not present at farrowing, meaning the number of piglets that were classified as “born dead” was probably greatly overestimated. Therefore, mean total litter size at birth (born dead + born alive, MTLS), its standard deviation (SDLS), litter size at weaning and percentage of total losses (born dead + lactation losses, pLOSS) were calculated at the farm level. Overall, MTLS was 12.9 ± 1.6 piglets at birth, 9.2 ± 1.1 piglets at weaning and pLOSS was 26.7 ± 7.1 % with a lactation duration of 45.3 ± 5.9 days. Mortality of piglets increased with MTLS (2.1 ± 0.7% additional loss per piglet, p = 0.004) and with SDLS (3.9 ± 1.6% additional loss per unit of SDLS, mean ± SEM, P = 0.021). MTLS was correlated with SDLS (r = 0.44, p = 0.006). These data confirm the detrimental influence of large litter size at birth on piglet mortality. This is commonly observed in conventional pig production and related to a higher proportion of piglets with low birth weight and to increased competition for teats. High variability in litter size may exacerbate these problems, and in addition may be an indicator for other problems on the farm

On the role of Zr and B addition on solidification cracking of IN738LC produced by laser powder bed fusion

The demand for manufacturing increasingly complex geometries for high temperature applications drives the increasing interest into additive manufacturing of nickel-based superalloys. Of particular interest are superalloys with high contents of the strengthening phase γ\u27 such as IN738LC. Previous research suggests that especially B and Zr have a detrimental influence on crack formation during the laser powder bed fusion (LPBF) process. The present study investigates solidification cracks in an IN738LC derivative with increased B (0.03 wt.%) and Zr (0.07 wt.%) in more detail using high resolution techniques such as transmission electron microscopy (TEM) and atom probe tomography (APT). Analysis of the bulk material shows a high number of MC carbides containing Ti and Cr. The concentration profiles indicate non-equilibrium carbide compositions by suggesting that Cr is pushed out of these particles. The carbides are surrounded by a thin B-rich layer at the metal/carbide interface. Analysis of the fracture surface shows both Zr and small amounts of B in the formed oxide layer. The presence of these elements together with thermodynamic calculations and previously reported findings of the same material variant support the hypothesis that low-melting phases are likely reasons for cracking of IN738LC