Clad Specimens Research Articles

Laser assisted deposition of graded overlay of Stellite 6 on austenitic stainless steel

Hardfacing by Stellite is extensively employed in many engineering applications for enhancing high temperature wear, oxidation and corrosion resistance of austenitic stainless steel components. These overlaid components, because of large difference in thermo-physical and mechanical properties between clad and substrate, are largely prone to cracking. Cracking resistance of Stellite 6 clad austenitic stainless steel components can be greatly enhanced by providing smooth composition gradient across substrate-clad interface. This article presents development of graded overlay of Stellite 6 on AISI 304 stainless steel substrate using 2.5 kW continuous wave CO 2 laser and their comparison with directly Stellite 6 clad AISI 304 stainless steel specimens. Graded overlaying of Stellite 6 effected significant reduction in microhardness gradient across substrate-clad interface with respect to that of directly Stellite 6 clad specimens. Thermal cycling tests, performed on laser-cladded specimens, demonstrated superi...

A New Method and Its Efficiency to Evaluate the Wrinkle-Resistance of Wool.

A novel method to evaluate the wrinkle-resistance of woolen fabrics is proposed together with several experimental tests to check its efficiency, which enables us to follow the relaxation behavior of fabrics from wrinkled states, with higher reliability as well as by with greater ease than the conventional methods such as the Multiple-Pleats Test, IWS Method, JIS-L-1059's A to D, etc. Experiments proved the method is strong in two respects: Good reproducibility can be achieved because measurement is always performed in the state at which the regain of the cloth specimen is saturated in the sample-conditioning atmosphere; and high precision or resolvability is guaranteed since the bias caused by the difference in humidity can be removed if the common conditions be set in all tests. This technique was applied to the analysis of the relaxation in the wrinkles that are brought on woolen slacks by actual wearing conditions. The results obtained, being compared with the laboratory ones, proved the practical validity of the new method and gave useful information.

Strain-controlled fatigue of a braze clad Al–Mn–Mg alloy at room temperature and at 75 and 180°C

Abstract Strain-controlled fatigue test results at room temperature, 75 and 180°C for a braze clad Al 1 Mn 0.5 Mg (wt.%) alloy with the designation 3005LL are presented. The tests have been executed on flat specimens with a 10 mm gauge length. The total strain ranges vary from 0.4 to 1.2%. The frequency is 0.5 Hz and the waveform triangular. The influence of the cladding on the fatigue properties is strain range dependent. The fatigue life for clad specimens is shorter than that for the unclad core material at higher strain ranges while the life difference is small at lower strain ranges. The results show that cracks during fatigue propagate through the brittle eutectic zones in the cladding layer and into the core, thereby degrading the fatigue life. The test temperature influences the fatigue properties of 3005LL. When the combination of stress and strain (half-life hysteresis energy) is considered as the controlling parameter for the strain-controlled fatigue of 3005LL, however, the fatigue properties are similar at different test temperatures.

Corrosion Fatigue Crack Growth in Clad Low-Alloy Steels—Part II: Water Flow Rate Effects in High-Sulfur Plate Steel

Corrosion fatigue crack propagation tests were conducted on a high-sulfur ASTM A302-B plate steel overlaid with weld-deposited Alloy EN82H cladding. The specimens featured semi-elliptical surface cracks penetrating approximately 6.3 mm of cladding into the underlying steel. The initial crack sizes were relatively large with surface lengths of 22.8–27.3 mm, and depths of 10.5–14.1 mm. The experiments were initiated in a quasi-stagnant low-oxygen (O2 < 10 pph) aqueous environment at 243°C, under loading conditions (ΔK, R, cyclic frequency) conducive to environmentally assisted cracking (EAC) under quasi-stagnant conditions. Following fatigue testing under quasi-stagnant conditions where EAC was observed, the specimens were then fatigue tested under conditions where active water flow of either 1.7 m/s or 4.7 m/s was applied parallel to the crack. Earlier experiments on unclad surface-cracked specimens of the same steel exhibited EAC under quasi-stagnant conditions, but water flow rates at 1.7 m/s and 5.0 m/s parallel to the crack mitigated EAC. In the present experiments on clad specimens, water flow at approximately the same as the lower of these velocities did not mitigate EAC, and a free stream velocity approximately the same as the higher of these velocities resulted in sluggish mitigation of EAC. The lack of robust EAC mitigation was attributed to the greater crack surface roughness in the cladding interfering with flow induced within the crack cavity. An analysis employing the computational fluid dynamics code, FIDAP, confirmed that frictional forces associated with the cladding crack surface roughness reduced the interaction between the free stream and the crack cavity.

Influence of Sulfate-Reducing Bacteria on Alloy 625 and Austenitic Stainless Steel Weldments

A series of welded austenitic stainless steel (SS) and alloy 625 (UNS N06625)-clad specimens were exposed to natural lake water inoculated with a mixed culture of anaerobic organisms high in sulfate-reducing bacteria (SRB). Total exposure was 300 days. The water and bacteria were taken from an actual service water system. Electrochemical testing included electrochemical impedance spectroscopy (EIS), monitoring of open-circuit potential (Eoc), and zero resistance ammetry (ZRA) tests. Comparison of electrochemical and visual observations to sterile controls indicated electrochemical behavior of all materials in the test matrix was influenced by the bacteria. Polarization resistance (Rp) and Eoc values were reduced dramatically. Attack was along the fusion line of the weld. The magnitude of these effects followed a trend predicted by the pitting index (PI) for each material.

Strip Cladding of Propeller Shafts with Nickel Alloy 625 by Electroslag Surfacing

A comprehensive comparison between electroslag surfacing (ESS) and submerged arc surfacing (SAS) using 30-mm-wide (1.2 in.) χ 0.5-mm-thick (0.020 in.) nickel alloy 625 strip was conducted in both the as-deposited and stress relieved (at 650°C [1200°F]) conditions. In most cases, exactly duplicate cladding conditions were used to best compare ESS with SAS. Nickel alloy 625 strip was deposited on 10-cm-thick (4 in.) flat plates and 64-cm-diameter (25 in.) shafting (both MIL-S-23284 Class 1 steel) using optimized ESS and SAS processes. Tension and face and side bend tests were performed on as-welded and stress-relieved cladding at room temperature. Microstructural analyses of the clad specimens were performed using optical and electron microscopy. Cladding parameters were found to affect the dilution, deposition rate, and penetration. Although ESS and SAS cladding possessed similar strength levels, the cladding deposited by ESS was shown to have greater ductility than that by SAS. Also, the resistance to solidification cracking of cladding by ESS was superior to SAS because of the reduced silicon, carbon, oxygen, and impurity levels which promote interdendritic Laves phase, niobium-rich MC carbides and inclusions. Compared with SAS, the ESS method proved to be not only more metallurgically favorable but also cost-effective.

Experimental and Computational Residual Stress Evaluation of a Weld Clad Plate and Machined Test Specimens

Residual stresses in a heat treated weld clad plate and test specimens obtained from the plate are determined using a combination of experimental residual stress analysis and a finite element computational model. The plate is 102 mm thick and made of A 533-B Class 2 steel with 308 stainless steel cladding. The plate is heated to 538 C and allowed to cool uniformly. Upon cooling, residual stresses are set up in the clad plate because of the difference between the coefficients of thermal expansion of the plate and the cladding. Residual stress in the clad plate is determined using both a previously verified experimental residual stress analysis technique and a computational model. Removing test specimens from the clad plate can relax the stresses in the cladding. Thus, residual stress distributions were also determined for two types of clad test specimens that were removed from the plate. These test specimens were designed to examine the effect of cladding thickness on residual stresses. Good agreement was found between the experimentally obtained residual stress values and the residual stresses calculated from the computational model. Because of the interest in tests conducted at elevated temperatures and the inherent difficulty in doing experimental residual stress analysis at elevated temperatures, the computational model was applied to examine the effect of elevated temperature on the residual stresses in the test specimens. Peak stresses in the heat treated clad plate were found to approach the yield stress of the cladding material. It was also found that removing a 32 mm clad specimen with cladding on one side reduced the residual stresses in the cladding. However, the residual stresses in the cladding were found to increase when one-half of the cladding thickness was machined away to form the second test specimen geometry. Residual stresses parallel and perpendicular to the weld direction were very similar in magnitude for all cases considered. The effect that heating the test specimens to 204 C has on residual stress distributions was to reduce the residual stress in the cladding and the plate.

AN APPROACH TO ASSESSING THE STAIN FASTNESS OF DYEINGS

The visual ratings on fastness of dyeings are influenced by many factors such as mental state of assessor, judging conditions, and so on. The variation factors of visual rating were examined. 307 sheets of stained cloth specimen were prepared by rubbing on 82 kinds of commercial clothing leather. The staining of the specimen was assessed with the Grey Scale by 26 assessors, making 7982 assessments in all.The agreement between the average and individual ratings within ±0.5 rating grade was found to be about 94% for all assessments.The formula which showed an extremely high correlation coefficient between the rating and the colour difference of the Grey Scale was proposed. The formula made it possible to calculate the rating of the stained specimen.By comparing the visual and calculated ratings for all assessors, it was found that the assessors have an inherent rating criterion which gave good reproducibilities to their own assessments. However, the internal criterion differed from each other too greatly among assessors. The dispersion of visual ratings was broadened with increase in the colour difference of the stained specimen. This is mainly due to the difference in the internal rating criterion among assessors.The difference threshold also increased with increase in the colour difference of the stained specimen. However, the difference threshold showed minor effect on broadening the dispersion of visual ratings.The cloth grey scale was prepared for the purpose of decreasing the difference in the internal criterion among assessors. It should be noted that the dispersion of visual ratings is fairly improved by using the cloth grey scale.

Method of testing the long-term strength of clad steels in corrosion-active media

Clad materials in which the substrate is represented by a carbon or low-alloy steel and the cladding layer is in the form a high-alloy steel are used to save very scarce corrosion-resisting materials. A method has been developed of examining the long-term strength of clad steels in corrosion-active media at high temperatures and pressures. The experimental setup provides provisions for pressurizing, heating, temperature measurement and stress measurement. The results show that the long-term strength of the clad specimens in hydrogen is higher than the strength of unprotected steel 20 in air at the same temperature. The metallographic examination of the clad specimens after testing for long-term strength at 500/sup 0/C and a hydrogen pressure of 58.8 MPa shows that at the ratio of the thicknesses of the cladding to main layers of 1:4 hydrogen has no effect on steel 20; however, surface decarburization of the main layer takes place at a ratio of 1:9. The specimens may be made of metals of almost any combination and any ratio of the thickness of the cladding to main layers.

Glass transition temperature (Tg) determination of partially cured thermosetting systems

AbstractPrevious experiments have shown that Tg of a partially cured thermosetting system can be measured with conventional thermal scan methods only if no appreciable additional cure occurred during the scan. For high temperature performance systems, the partially cured Tg is often at a temperature where kinetics rate is very rapid, causing either an observation of a more advanced cured Tg, or only the completely cured system's Tg [Tg (∞)]. Two methods to interpolate the Tg information in spite of additional cure are presented and illustrated with an epoxy resin as a testing material. The Isocure State Curve method is demonstrated with a two‐step curing experiment with the Torsion Impregnated Cloth Analysis (TICA) technique, which is a forced torsion measurement on the Rheometrics mechanical spectrometer, with the resin impregnated on a glass cloth specimen. The calibration method is demonstrated by the post cure experiments of TICA, using the time to loss modulus maximum, and the softening parameter R as the calibration parameters.

Amplitude dependence of the internal friction of plasma-sprayed coatings

An internal friction study of plasma-sprayed coatings has shown that the application of such coatings substantially changes the ADIF parameters (decreases ɛcr and increases tan α) of a clad specimen. The effects of the dislocation structure of a basis on the physicomechanical properties of a plasma-sprayed coating applied to it have been established.

Fracture Behaviors of Fracture Toughness Testing Specimen with Heterogeneity Along Crack Front

Fracture toughness tests of specimens with mechanical and metallurgical heterogeneity along crack front have been conducted. Using specimens cut from stainless clad steel (high tensile strength of 80 kg/mm2 strength level with SUS 304 stainless steel), both the conventional V-notch Charpy test and the bending COD test are performed to investigate the effect of the heterogeneity on the process of fracture and the fracture toughness controlling parameters.Absorbed energy of clad specimen in V-notch Charpy test is affected by various complicate factors such as fractions of brittle regime, energy for initiation of crack in the vicinity of notch tip, and energy for propagation of crack. In the heterogeneous material, absorbed energy in Charpy test may not be a proper fracture toughness parameter. The processes of fracture of static bending notched specimens are as follows : At low temperature, cleavage type fracture firstly initiates only in HT 80 steel region, and at high temperature, ductile fracture firstly initiates in SUS 304 steel region. In the case of fracture toughness testing of heterogeneity materials, it seems that stretched zone width can be a proper parameter of fracture toughness in particular relation to crack initiation. Fracture toughness values when original crack initiates in the some parts along crack front are roughly equal to those of specimens filled with the lower-toughness materials in crack front.

The Effect of Mean Stress on Fatigue Crack Propagation in Plates Under Extension and Bending

An earlier study of fatigue crack propagation in thin plates under fluctuating plane extension and cylindrical bending is extended to include the effect of nonzero mean stress. The theoretical considerations are applied to existing data and to new data obtained from 2024-T3 bare and clad aluminum specimens subjected to fully reversed and nonsymmetric bending loads. For the ranges studied, the agreement between the data and the model developed seems to be very good.

Radiocarbon Dates from Ellsworth Falls, Maine

Through the kindness of H. R. Crane and the Radiocarbon Laboratory, Michigan Memorial, Phoenix Project, ages of 2 samples of charcoal submitted by us have been determined. The samples in question were secured by us at the Smith Farm, Ellsworth Falls, Maine, during the summers of 1949 and 1950. Sample M89 was run twice and assays at 4150±450, and 3800±400, average 3959 ±310 or 2005 B.C. Sample M90 assays at 3350 + 400 or 1400 B.C.These samples were gathered and brought in under circumstances that would be frowned on today. Pieces of charcoal were put in cloth specimen bags which had been used several times and laundered in a washing machine. Workers had not at that time received instructions regarding methods and containers, and it is certain that some of the pieces were brought in in sandwich bags. Whatever the method of collecting, results are consistent with other radiocarbon dates for comparable horizons in the northeast.