Seam Area Research Articles

The origin of weld seam defects related to metal flow in the hot extrusion of aluminium alloys EN AW-6060 and EN AW-6082

Longitudinal weld seams are an intrinsic feature in hollow extrusions produced with porthole dies. As these joins occur along the entire extruded length, it is desirable that these weld seams have a minimal impact on the structural integrity of the extrudate. In particular, defects associated with weld seam formation should be avoided. In this research, the occurrence of defects related to material flow inside the extrusion tooling is studied. In lab-scale experiments, EN AW-6060 and EN AW-6082 aluminium alloy billets are formed into strips by means of the direct hot extrusion process. By utilising model dies with an internal obstruction similar to the supports present in porthole dies, a strip with a central longitudinal weld seam is formed. The effects of different geometries of the weld-chamber and the processing conditions on the quality of the weld seam are investigated. Characterisation is performed through mechanical testing, focusing on the ability of the weld seam area to accommodate plastic deformation, and microstructural analysis provides insight into the defects related to unsound metal flow. Through computer simulations, conditions related to weld seam formation are modelled and correlated with the experimental results. The experimental results demonstrate that metal flow controlled by the die geometry causes defects leading to inferior mechanical performance of the extrudate. It is further argued that current weld seam formation criteria utilised in finite element modelling need enhancement to incorporate these flow related defects.

An Investigation on Vacuum Brazing of Dissimilar Nonferrous Metals of Cu and Al

The writer successfully obtained brazed Cu-Al joint by using vacuum brazing method, and also conducted an analysis for the microstructure morphology of the joint. The result shows that: The interface of the brazed Cu-Al joint includes three parts---the transition area on the Cu side, the central brazing seam area and the transition area on the Al side. Formed between the brazing seam area and the Cu substrate are the Cu3Al2 and CuAl2 layers, and the average width of the transition area of Cu3Al2 is 12 μm while that of CuAl2 8 μm. The brazing seam area is mainly composed of α-Al solid solution, Cu3Al2 and CuAl2 metal compounds, in addition, the ε-Cu15Si4 phase, the Al-Si phase and CuZn2 phase are also formed. These phases present themselves in the state of acicular compounds, which are dispersed in the brazing seam area.

Numerical investigation of the influence of preliminary manufacturing processes on the crash behaviour of automotive body assemblies

The simulation of the crash behaviour of whole automotive body structures has gained increasing value in the development phase of the overall product cycle in the recent years. In the automotive body-in-white cost and time as well as high accuracy and quality of structural components are main issues. Particularly, when it comes to safety matters, the crash behaviour of the overall vehicle shell is a major concern. So as to describe the manufacturing process chain more precisely and to predict the structural behaviour at early stages of product and process planning, an interlinking of forming, trimming and welding models within a structural manufacturing computation chain is necessary. The computed structural properties after manufacturing and joining of body assemblies appear to be essential for a more accurate description of the actual crash behaviour. Considering the structural properties after the forming and trimming process for simulating welding tasks and finally the crash behaviour requires a multifaceted modelling method. In this paper, a practicable strategy for realising the simulation chain forming–welding–crash of whole structural assemblies by means of shell element models is introduced. The complete computed results of a forming process simulation, such as residual stresses, plastic strains, and material thinning are transferred into the simulation of welding heat effects. Further on, the structural properties after forming combined with the thermal distribution due to the welding process and the mechanical clamping conditions within a thermomechanical computation allow a conclusion on the final shape, residual stresses and plastic strains in the weld seam area of the manufactured structure. Finally, the attained structural results are converted into the required data format by means of a developed conversion routine, which enables the side crash simulation of a sill board assembly automotive structure on a rigid pole considering the entire preliminary manufacturing process chain.

Advanced forecast of coal seam thickness variation by integrated geophysical method in the laneway

Abstract Coal seam thickness variation has a direct relationship with coal mine design and mining, and the mutation locations of the thickness are generally the gas accumulation area. In order to justify the feasibility and validity of advanced forecast about the thickness change, we carried out geophysical numerical simulation. Utilizing generalized Radon transform migration, coal-rock interface can be identified with an error of less than 2%. By the calculation of 2.5D finite difference method, transient electric magnetic response characteristics of the thickness variation is conspicuous. In a coal mine the case study indicated that: the reflected wave energy anomaly offer interface information of the thickness change point; the apparent resistivity provide the physical index of the thick or thin coal seam area; synthesizing two kinds of information can predict the thickness variation tendency ahead of the driving face, which can ensure the safety of driving efficiency.

Assessment of the influence of surface finishing and weld joints on the corrosion/oxidation behaviour of stainless steels in lead bismuth eutectic

The objective of this paper is to gain some insight into the influence of the surface finishing in the oxidation/corrosion behaviour of 316L and T91 steels in lead bismuth eutectic (LBE). Specimens of both materials with different surface states were prepared (as-received, grinded, grinded and polished, and electrolitically polished) and oxidation tests were carried out at 775 and 825 K from 100 to 2000 h for two different oxygen concentrations and for H 2/H 2O molar ratios of 3 and 0.03. The general conclusion for these tests is that the effect of surface finishing on the corrosion/protection processes is not significant under the tested conditions. In addition the behaviour of weld joints, T91–T91 Tungsten Inert Gas (TIG) and T91–316L have been also studied under similar conditions. The conclusions are that, whereas T91–T91 welded joint shows the same corrosion properties as the parent materials for the conditions tested, AISI 316L–T91 welded joint, present an important dissolution over seam area that it associated to the electrode 309S used for the fabrication process.

Study on Corrosion Resistance of 316L Stainless Steel Welded Joint

Abstract The morphology, phase, pitting corrosion behaviors and galvanic corrosion resistance behavior of the welded joint of 316L stainless steel and Ti(TA2) clad plate were studied by scanning electron microcopy (SEM), X-ray diffraction (XRD), zero-internal resistance ammeter and potentiodynamic polarization technique. The results show that the welded 316L presents severe deformation and has intermetallic phase; moreover, more δ-ferrite phase emerges at the welded seam and fusion area near 316L side. All these factors lead to the decrease of pitting corrosion resistance and galvanic corrosion resistance of the welded 316L.

Towards Predictive Control of Extrusion Weld Seams: An Integrated Approach

Longitudinal weld seams are an intrinsic feature in hollow extrusions produced with porthole dies. The formation of longitudinal weld seams is a solid bonding process, controlled by the local conditions in the extrusion die. Being the weakest areas within the extrusion cross section, it is desirable to achieve adequate properties of these weld seams. In our research, the concept of a weld seam integrity indicator as a means of quantifying bonding efficiency is introduced. The value of this indicator depends on a number of factors: the material flow within the die weld chambers, an adequate pressure level acting on the weld planes and finally the evolution of the metal microstructure. Optimisation of the welding conditions leads to a higher value of the weld seam integrity indicator and thus to improved weld seam properties. The objective of the research presented in this paper is to assess the feasibility of this concept. In lab-scale experiments, AA6060 and AA6082 aluminium alloy billets were formed into strips by means of the direct hot extrusion process. By utilising porthole dies a central longitudinal weld seam is formed. The effect of different geometries of the weld chamber and the processing conditions on the quality of the weld seam are investigated. Characterisation of these weld seams through mechanical testing, focusing on the ability of the weld seam area to accommodate plastic deformation following the onset of plastic instability, and microstructural analysis provides insight into bonding performance. The outcome of this characterisation provides a basis for an estimation of the weld seam indicator. Through computer modelling, the particular process conditions related to weld seam formation are calculated and correlated with the experimental results. The experimental results clearly demonstrate that weld seam formation is controlled by a combination of factors as described above. Inadequate fulfilment of these conditions, verified by the FE-simulations, is the cause of inferior weld seams, associated with low values of the weld seam integrity indicator. Through further elaboration of the concepts presented in this work, the weld seam integrity indicator is to be developed, with the future aim of predicting the weld seam performance through finite element simulations.

Reflectivity forward modeling and a CSSI method seismic inversion study of igneous intrusive area, coked area, and gas-enriched area located within a coal seam

We applied the reflectivity method and the constrained sparse spike inverse modeling (CSSI) method to the interpretation of coal field lithologic seismic data. After introducing the principles of these two methods we discuss some parameters of a geological model involving possible gas enriched areas or intruded igneous rock. The geological model was constructed and a 60 Hz seismic response profile was obtained looking for igneous rock intrusion and coked areas of the coal seam using the reflectivity method. Starting from synthesized logging data from two wells and a synthesized seismic wavelet we calibrated the model to show accurate strata. Finally, we predicted the lithology within a 10 m igneous rock area, a 3 m coal seam area, and a coked area using the CSSI technique. The results show that the CSSI technique can identify hard to recognize lithologic features that normal profiling methods might miss. It can quantitatively analyze and evaluate the intrusive area, the coked area, and the gas-enriched area.

Influence of local heat treatment on residual stresses in electron beam welding

Electron beam welding (EBW), as a high performance welding method, is also subject to requirements of high integrity welds which particularly include residual stresses affecting distortion and fatigue behaviour. In this context multiple beam technique may provide new applications of specific thermal weld treatment. The present work introduces a promising method of local post-heating in a certain distance to the current welding location applying multiple beams for the reduction in residual stresses in EB welded sheet metals. The conducted investigations include finite element analysis (FEA) and stress measurements in the weld seam area. Using a systematic approach within the FEA decisive process parameters are optimised with reference to the achievable reduction in residual stress. All simulation results are validated by experiments applying strain gauges for the stress measurement. Both simulations and experiments revealed a considerable decrease in residual stress achievable by appropriate positioning of additional heat sources combined with the right power input and beam focusing.

Enveloping bioabsorbable polyglycolide membrane and immobilization in achilles tendon repair: A comparative experimental study on rabbits

Using qualitative and histoquantitative methods, we investigated the effect of immobilization versus nonimmobilization on the biodegradation process, implant-tissue interaction, and scar formation after enveloping a rejoined rabbit Achilles tendon with a self-reinforced polyglycolide (SR-PGA) membrane. The soleus and gastrocnemius tendons of the right hind legs of 40 rabbits were transected. After suturing the ends, the seam was enveloped with the bioabsorbable membrane. Twenty ankles were immobilized with cast, 20 remained nonimmobilized. All nonoperated left ankles served as intact controls. During the follow-up of 3, 6, 12, and 24 weeks, scar formation, tissue response, and membrane biodegradation were studied histologically and histomorphometrically. The amount of scar tissue, highest at 3 weeks, gradually approached intact controls. SR-PGA degradation in both cast and noncast specimens was near complete by 24 weeks. Signs of an inflammatory process were most prominent at 3 weeks and diminished gradually by 24 weeks. No significant difference between cast and noncast specimens was noted at any time point regarding the amount of scar tissue, degradation process of PGA, or intensity of inflammatory reaction. In the present experimental setting, cast immobilization influenced neither scar formation nor speed of degradation during reunion of transected Achilles tendon ends as compared with nonimmobilization. No differences in the reunion process of the tendon ends were seen between the immobilized and nonimmobilized groups. Moreover, inflammatory cells were similar in both groups and reflected a transient tissue reaction to the membrane. Within the follow-up, the seam area (cross-sectional) approached that of intact controls.

Ontogeny of Androgen Receptor and Disruption of Its mRNA Expression by Exogenous Estrogens During Morphogenesis of the Genital Tubercle

The ontogeny of androgen receptor expression in male and female mouse genital tubercles, and the effects of in utero ethinyl estradiol exposure on androgen receptor mRNA expression in the hypospadias model were studied. Androgen receptor mRNA expression was measured in mouse genital tubercles from fetuses and pups collected on gestational days 12, 14, 16 and 18, and from newborns using immunohistochemistry and real-time quantitative polymerase chain reaction. Pregnant dams were exposed to ethinyl estradiol or corn oil as controls from gestational days 12 to 17. Genital tubercles of gestational day 19 fetuses were then examined by further quantitative polymerase chain reaction analysis after identification of the seam area using a dissecting microscope to diagnose hypospadias in males. Androgen receptor protein was detected in genital tubercles by gestational day 14. Androgen receptor mRNA expression increased gradually in each sex during normal development. However, female genital tubercles expressed a higher level of androgen receptor mRNA throughout development compared to male genital tubercles (p <0.0001). In utero ethinyl estradiol exposure led to a 5.4 and 4.5-fold increase in androgen receptor mRNA in the genital tubercles of female and male embryos (p = 0.004 and 0.001, respectively). Hypospadiac male genital tubercles showed increased androgen receptor mRNA expression compared to control males (p = 0.006). Levels in hypospadiac males did not differ from those in control females but they were less than those in ethinyl estradiol treated females (p >0.05 and 0.01, respectively). Androgen receptor protein is expressed abundantly in male and female genital tubercles. Androgen receptor mRNA levels are higher in female than in male genital tubercles through development and they increase in response to in utero ethinyl estradiol exposure with ethinyl estradiol treated females having the highest levels of expression, followed by ethinyl estradiol treated hypospadiac males. We infer that higher estrogen in genital tubercles results in a physiological response of increased androgen receptor mRNA expression. We found no direct association between changes in androgen receptor mRNA expression and the presence or absence of hypospadias in males, suggesting that alterations in the expression of proteins other than or in addition to androgen receptor result in anomalous urethral development. This finding supports the idea that the etiology of hypospadias is multifactorial in origin.

IN UTERO PREDNISONE EXPOSURE AFFECTS GENITAL DEVELOPMENT

The etiology of the worldwide incidence of hypospadias remains unexplained. Data from the Center for Disease Control suggest that maternal asthma exposure may be a risk factor. The development of the mouse and human urethra shows significant similarities, such as fusion of 2 epithelial edges, closure of a midline epithelial seam and subsequent cellular remodeling, to justify the use of the mouse as an experimental animal model. Prednisone may act as a weak androgen directly or alternatively lowering testosterone by hypothalamic suppression of gonadotropins. We describe the effects of prednisone on urethral formation in the mouse. The model comprised 10, 20 and 20 timed pregnant C57/6 mice exposed to 1,000, 200 and 100 mg/kg prednisone, respectively, on gestational days 12 through 18. The morphology of the genital tubercles of both sexes were examined on gestational day 19 using histological techniques and 3-dimensional computer reconstruction. Specific attention was focused on the developing urethral seam. Microscopic serial analysis confirmed the presence of an arrest in seam formation in approximately 25% of male fetuses given supraphysiological doses of prednisone (1,000 mg/kg). In contrast, acceleration of urethral fold fusion and a longer urethral tube were observed in those males treated with 100 and 200 mg/kg prednisone. The female fetuses treated with the same dosages of prednisone did not show any change at the level of the urethral seam area or in the remainder of the genital tubercles. Supraphysiological doses of prednisone treatment has an inhibitory effect on urethral fold fusion leading to hypospadias whereas low doses accentuate urethra formation in male mouse fetuses. In mice lower doses do not cause hypospadias in the males or affect urethral formation in females.

The effect of oestrogen and testosterone on the urethral seam of the developing male mouse genital tubercle.

To describe the effects of exogenous oestrogens and androgens on urethral formation in the mouse, as the development of the mouse and human urethra have significant similarities, and understanding normal male urethral development may help to identify the causes of abnormal development, e.g. hypospadias. Timed-pregnant C57/6 mice were exposed to synthetic oestrogens and androgens. The morphology of the genital tubercles was examined histologically and with three-dimensional computer reconstruction. Specific attention was focused on the developing urethral seam. Microscopic serial analysis confirmed the presence of an arrest in seam formation in about half of oestrogen-treated male fetuses. In contrast, there was acceleration of urethral fold fusion and a longer urethral tube in those treated with androgens. Oestrogen-treated fetuses had a thin periurethral spongiosa, in contrast to androgen-treated fetuses which developed a thicker periurethral spongiosa. The effect of oestrogens on seam area formation did not depend on the dose, but in contrast, in the androgen-treated fetuses it was. Oestrogens and androgens have a direct effect on the fusion of the urethral fold that leads to seam formation. Normal urethral development depends on the delicate balance of these complementary hormones.

Long‐Term Properties of Butt‐Welded Poly(propylene)

AbstractIt is still not clear why the long‐term properties of plastic weld seams can only be differentiated by the very expensive medium tensile creep tests. One hypothesis for justifying this is based on the change in the structure of the weld seam surroundings, another cites the consumption of antioxidants and the following ageing in the weld seam area to be responsible for this. Butt‐welded weld seams made of poly(propylene) were systematically produced under different process parameters. Corresponding to the particular hypothesis, these weld seams were then analyzed in various ways to find correlations or to prove one of the hypotheses. Regarding their short‐term weld seam quality, the analyzed weld seams could not be differentiated through short‐term tensile or short‐term bend test. However, the medium tensile creep tests showed significant differences in both time until failure and long‐term weld seam quality. Under long‐term loading, the start of the brittle crack could be detected in most weld seams in the fine spherulite‐zone or between this zone and the area of the flow lines. This demonstrated again that only long‐term tests are suitable for examining different weld seam qualities. Depending on the welding parameters, times until failure decline with increasing heated‐tool temperature and heating time. Though these parameters lead to a higher consumption of antioxidants in the weld seam, a degradation was not detected in the breaking area. In fact, increasing heated‐tool temperatures and heating times, as well as higher joining pressures lead to a change in the internal structure of the material. This can be seen in morphological structure analyses in the larger bend of the entire weld seam area. A larger bend, however, correlates with higher residual stresses in the weld seam. In the medium tensile creep tests, these residual stresses as well as the tensile stress in the border region and the compressive stress in the middle are superimposed by the tensile stress resulting from the test stress. Thus a greater bend of the weld seam area and higher residual stresses in the weld seam itself lead to shorter times until failure in medium tensile creep tests.Schematic representation of the formation of residual stresses in a weld seam and residual stresses in the different bended weld seam areas.magnified imageSchematic representation of the formation of residual stresses in a weld seam and residual stresses in the different bended weld seam areas.

Expression of the androgen receptor and 5 alpha-reductase type 2 in the developing human fetal penis and urethra.

Normal penile development is dependent on testosterone, its conversion via steroid 5 alpha-reductase type 2 to dihydrotestosterone, and a functional androgen receptor (AR). The goal of this study was to investigate the distribution of AR and 5 alpha-reductase type 2 in the developing human fetal external genitalia with special emphasis on urethra formation. Twenty fetal genital specimens from normal human males (12-20 weeks gestation) were sectioned serially and stained by avidin-biotinylated peroxidase complex method with antigen retrieval. Stained sections throughout male genital development documented the expression of AR and 5 alpha-reductase type 2 in the phallus. Between 12 and 14 weeks of gestation, AR was localized to epithelial cells of the urethral plate in the glans, the tubular urethra of the penile shaft, and stromal tissue surrounding the urethral epithelium. In the fetal penis between 16 and 20 weeks gestation, the density of AR expression was greatest in urethral epithelial cells versus the surrounding stromal tissues. There was a characteristic pattern of AR expression in the glandular urethral epithelium between 16 and 20 weeks gestation. AR expression was greater along the ventral aspect of the glandular urethra than along the dorsal aspect of the urethral epithelium. The expression of 5 alpha-reductase type 2 was localized to the stroma surrounding the urethra, especially along the urethral seam area in the ventral portion of the remodeling urethra. These anatomical studies support the hypothesis that androgens are essential for the formation of the ventral portion of the urethra and that abnormalities in either the AR or 5 alpha-reductase type 2 can explain the occurrence of hypospadias.

Effect of testosterone on bone mineralization of the hypophosphataemic rat.

Clinical observations in patients with X-linked hypophosphataemic rickets, that bone changes can be corrected during puberty, suggest that androgen can participate actively in the process of bone mineralization. In the present study we investigated the role of testosterone on the bone mineralization of male rats placed on a low phosphorus and vitamin D diet and kept in complete darkness after weaning. After 15 days the animals presented hypophosphataemia, rickets and osteomalacia, as assessed by histomorphometry of the tibia and seventh caudal vertebra calcification fronts respectively. Testosterone propionate administration for five days, while the animals were kept on the same rachitogenic diet, induced an improvement in the bone mineralization process of the hypophosphataemic rat independently of serum phosphate levels. Testosterone-treated rats were cured of rickets but not of osteomalacia, despite the reduction in osteoid seam area.

An Application of Fourier Transform Infra-red (FT-IR) Microspectroscopy to the Study of Cigarette Manufacturing Defects

Abstract FT-IR microspectroscopy was used to investigate a common type of cigarette defect in which the filter separates from the tobacco rod. Infra-red imagings of the adhesive located at this junction on the tipping papers from both defective and acceptable cigarettes were obtained. A comparison of these data revealed that although adhesive was present in the seam area of the defective cigarettes, the amount of adhesive was significantly less and its distribution was not uniform.

39227 Recent European work on the NDT of composite materials : Reynolds, W.N. Materials and Design, Vol. 9, No. 4, pp. 183–191 (Jul./Aug. 1988)

Scanning acoustic microscopy (SAM) is a modern, powerful technology for the visualization of the internal structure of materials of a different nature. It uses high frequency ultrasonic waves to get information from inside inhomogeneities and therefore is a sensitive, precise and safe method for materials characterization. It is successfully used in scientific and research practice but has the greatest potential as a technology for nondestructive quality evaluation. This chapter describes the methodology and different aspects of ultrasonic inspection performed on a variety of material samples using a scanning acoustic microscope working in the range of 10–400 MHz as an example. The samples come from different areas of material sciences and were intentionally chosen as containing defects specific to each case.Compared to the widely used nondestructive technique and medical ultrasound, SAM operates with higher frequencies and at relatively short distances. The acoustic beam emitted by the transducer passes through a coupling liquid and is reflected back by inhomogeneities in the sample structure. The strength of the reflected signal is determined by the change in characteristic acoustic impedance at such an inhomogeneity. The reflections captured in the digitized received signal (A-scan) represent a 1-D property distribution along the acoustical beam. The ultrasonic image is digitally constructed from a series of A-scans acquired during lateral scanning, when the acoustic microscope scans with a mechanical motion of a single acoustic lens along the sample surface and as a result generates (collects) 3-D data about the micromechanical properties of the object in this particular volume. The main types of images obtained by acoustic microscopes are B-scan and C-scan. More complex data processing algorithms produce enhanced images that can also be attributed to these two categories. A B-scan represents the 2-D distribution of amplitudes along the axial and the lateral coordinates (vertical cross-section). A C-scan represents the 2-D distribution of amplitudes in a lateral plane at a certain time delay after the initial pulse has been emitted from the transducer (horizontal cross-section). In addition to such efficient digital characterizations of internal microstructure, it was demonstrated that SAM technology can effectively detect, evaluate, and classify a wide range of different imperfections: porosity in aluminum casting, undersized and cavernous resistance spot welds, low penetration depth of laser weld seam, insufficient or damaged area of adhesive bonding of metals and fiber-reinforced composites, biocomposites and biomaterials, etc. The precision and value of the obtained acoustic images are dependent on frequency and particular methodology, and in some industrial application cases could even be proven by destructive testing. The samples come from different areas of material sciences and were intentionally chosen as containing defects specific to each case.

Faster and more accurate testing : Green, J.E. Jr. Advanced Materials and Processes, Vol. 131, No. 1, pp. 72, 75–76, 79–80 (Jan. 1987)

Scanning acoustic microscopy (SAM) is a modern, powerful technology for the visualization of the internal structure of materials of a different nature. It uses high frequency ultrasonic waves to get information from inside inhomogeneities and therefore is a sensitive, precise and safe method for materials characterization. It is successfully used in scientific and research practice but has the greatest potential as a technology for nondestructive quality evaluation. This chapter describes the methodology and different aspects of ultrasonic inspection performed on a variety of material samples using a scanning acoustic microscope working in the range of 10–400 MHz as an example. The samples come from different areas of material sciences and were intentionally chosen as containing defects specific to each case.Compared to the widely used nondestructive technique and medical ultrasound, SAM operates with higher frequencies and at relatively short distances. The acoustic beam emitted by the transducer passes through a coupling liquid and is reflected back by inhomogeneities in the sample structure. The strength of the reflected signal is determined by the change in characteristic acoustic impedance at such an inhomogeneity. The reflections captured in the digitized received signal (A-scan) represent a 1-D property distribution along the acoustical beam. The ultrasonic image is digitally constructed from a series of A-scans acquired during lateral scanning, when the acoustic microscope scans with a mechanical motion of a single acoustic lens along the sample surface and as a result generates (collects) 3-D data about the micromechanical properties of the object in this particular volume. The main types of images obtained by acoustic microscopes are B-scan and C-scan. More complex data processing algorithms produce enhanced images that can also be attributed to these two categories. A B-scan represents the 2-D distribution of amplitudes along the axial and the lateral coordinates (vertical cross-section). A C-scan represents the 2-D distribution of amplitudes in a lateral plane at a certain time delay after the initial pulse has been emitted from the transducer (horizontal cross-section). In addition to such efficient digital characterizations of internal microstructure, it was demonstrated that SAM technology can effectively detect, evaluate, and classify a wide range of different imperfections: porosity in aluminum casting, undersized and cavernous resistance spot welds, low penetration depth of laser weld seam, insufficient or damaged area of adhesive bonding of metals and fiber-reinforced composites, biocomposites and biomaterials, etc. The precision and value of the obtained acoustic images are dependent on frequency and particular methodology, and in some industrial application cases could even be proven by destructive testing. The samples come from different areas of material sciences and were intentionally chosen as containing defects specific to each case.

Composition of Seams in Cheddar Cheese

The material comprising the obvious light-colored seams in some Cheddar cheeses now commercially available was analyzed in situ and after isolation. From the data obtained, it was concluded that the seam material contained primarily whey proteins, slightly elevated levels of chloride, calcium and phosphate. Some fat was also present but was not studied. The seam area is characterized by a pH approximately one unit higher than the bulk cheese. The ratio of calcium to phosphate indicates that it may be present in the form of calcium orthophosphate.