Ni Cr Mo Alloy Research Articles

Investigations on the behavior of laser cladding Ni–Cr–Mo alloy coating on TP347H stainless steel tube in HCl rich environment

Combustion of biomass with a high content of alkali and chlorine can result in operational problems including deposition and rapid corrosion of critical components such as superheater tubes. Alloy modification is an effective way to reduce corrosion problems. Considering the excellent corrosion resistance but high cost of Ni–Cr–Mo alloy bar, the microstructure and high-temperature corrosion behaviors of the laser cladding Ni–Cr–Mo alloy coating were investigated and compared with the Ni–Cr–Mo alloy bar and the biomass boiler superheater tube material TP347H stainless steel in this study. Corrosion exposures were carried out in a tube furnace under simulated combustion gases containing 12%CO2–5%O2–0.05%HCl–N2 for 168h at 650°C and 700°C. The performance of three materials was evaluated by means of several analysis methods including: kinetic analysis (corrosion rate), SEM (microcosmic morphology of surface and cross-section),EDS (distribution of elements of cross-section) and XRD (phases formed on the surface layer). Compared to the other two materials, the overall performance was better for the laser cladding Ni–Cr–Mo alloy coating which on one hand had optimal ratio of corrosion resistance elements and on the other hand had grain strengthening effect by laser cladding technique.

Statistical analysis of composition fluctuations and short-range order in stoichiometric Ni–Cr–Mo alloys

In the solution treated state Ni-Cr-Mo based alloys exhibit short-range order characterized by the appearance of diffuse intensity spots in electron diffraction patterns at {1 ½ 0} positions. This short-range order appears due to of the formation of chemical heterogeneities. In the present work we report on the investigation of short-range order in Ni-33 at% Cr and Ni-16.7 at% Cr-16.7 at% Mo alloys using transmission electron microscopy. Chemical heterogeneities and their sizes are analyzed by statistical methods applied to three-dimensional atom probe data obtained on the same alloys. The obtained chemical heterogeneities are correlated to regions of short-range order in Ni-33 at% Cr and Ni-16.7 at% Cr-16.7 at% Mo alloys.

Determination of critical pitting temperatures for NiCrMo alloys using electrochemical noise measurements

The determination of critical pitting temperatures (CPT) in various test solutions like ferric chloride solution according to ASTM G48 or “Green Death” solution is a common test method for the comparative assessment of the pitting corrosion resistance of highly alloyed steels and NiCrMo alloys. In addition to the well-known disadvantages of standard methods, like long test times, subjective examination, and large scatter, for the highest alloyed NiCrMo alloys no stable pitting corrosion can initiate even at the highest test temperatures. This paper describes the limitations of standard test methods and shows how these problems can be solved by an alternative test solution and an adjusted test method. By capturing and examining the current noise under potentiostatic conditions during continuous heating in a 4.5 M calcium chloride solution the transition from metastable to stable pitting corrosion as a criterion for CPT can be detected in a reproducible way.

Coherent Ni2(Cr, Mo) precipitates in Ni–21Cr–17Mo superalloy

The microstructure of Ni2(Cr, Mo) precipitates in a Ni–21Cr–17Mo (wt.%) superalloy subjected to a two-step heat treatment has been investigated via high-resolution transmission electron microscopy and electron diffraction, combined with image and diffraction calculations. Various high-density nanoscale Ni2(Cr, Mo) precipitates were distributed homogeneously in the Ni–Cr–Mo matrix, and no other marked secondary phase was observed in the age-hardened alloys. The typical orientation relationship between the precipitates and the Ni–Cr–Mo matrix was determined as (200)matrix//(103) Ni2(Cr,Mo), [001]matrix//[010] Ni2(Cr,Mo). The interfaces between the precipitates and the surrounding matrix were coherent at the atomic scale, resulting in the remarkable improvement on the alloy strength after heat treatment. Moreover, the Ni2(Cr, Mo) particles exhibited a special oval shape, with the long axis perpendicular to the long-range-ordered plane of (Cr, Mo), that is, (220)Ni. A high spatial resolution chemical composition analysis revealed that the Ni2(Cr, Mo) precipitates were enriched in Mo, with an average composition of ∼19wt.% Cr and ∼20wt.% Mo, which probably caused the easy precipitation of the long-range-ordered Ni2(Cr, Mo) phase precipitated in Ni–Cr–Mo alloys with a high Mo content.

Characterization of film properties on the Ni[sbnd]Cr[sbnd]Mo Alloy C-2000

The passive and transpassive film properties grown at various potentials on a NiCrMo alloy, Alloy C-2000 (Ni23Cr16Mo1.6Cu), were investigated by surface-sensitive techniques such as Angle-Resolved X-ray Photoelectron Spectroscopy (AR-XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and SEM. The presence of a layered structure in the passive film has been demonstrated, with the outermost surface being enriched in Cu (or Cu oxide) and Mo oxide, the intermediate region dominated by Cr/Ni hydroxides, and the inner region comprising Cr/Ni oxide.As the potential increases from −0.4 to 0.6V (vs. Ag/AgCl in saturated KCl), the film thickness increases, and the relative Cr content of the film increases while that of Ni decreases. The passive film (0V) has a relatively thicker inner oxide layer and higher Cr2O3 content in the inner layer, compared to the near-passive film (−0.4V). In the transpassive region (0.6V), the anodic oxidation of Cr(III) to Cr(VI) in the barrier layer of the film and its subsequent dissolution leads to the loss of the Cr2O3-rich inner layer and the destruction of passivity. Destruction of the barrier layer proceeds non-uniformly on the alloy surface.

Chemical compatibility and electrical contact between Ni–Cr–Mo alloy and LaCo0.6Ni0.4O3−δ in intermediate temperature solid oxide fuel cells

The contact resistance and chemical compatibility of LaCo0.6Ni0.4O3−δ (LCN) coated Ni–Mo–Cr alloy are investigated at 750 °C in air for more than 530 h to simulate the contact situation of cathode/contact layer/interconnect in SOFC stacks. With La0.72Sr0.18MnO3 (LSM) as the cathode, the area specific resistance (ASR) of LSM/LCN/Ni–Mo–Cr alloy assembly increases to a maximum of 240 mΩ cm2 during the early stage of the test, and decreases after 55 h to a steady level of ∼220 mΩ cm2 till the end of the test. The contribution of formed oxide scale on the alloy to the measured ASR is negligible, compared to that of big AgLaMo2O8 particles sporadically distributed in LCN matrix. AgLaMo2O8 is formed of evaporated Mo from the alloy, Ag from the testing lead and La from the LCN before the oxide scale on the alloy is well developed. This reaction is expected to cease once the oxide scale is fully established.

Characterization of air-formed surface oxide film on a Co–Ni–Cr–Mo alloy (MP35N) and its change in Hanks’ solution

The air-formed surface oxide films used for stents were characterized to determine their composition and chemical state on a Co–Ni–Cr–Mo alloy. The change of the films in Hanks’ solution was used to estimate the reconstruction of the film in the human body. Angle-resolved X-ray photoelectron spectroscopy was used to characterize the composition of the film and substrate, as well as the film's thickness. The surface oxide film on the Co–Ni–Cr–Mo alloy (when mechanically polished) consists of oxide species of cobalt, nickel, chromium, and molybdenum, contains a large amount of OH−, and has a thickness of approximately 2.5nm. Cations exist in the oxide as Co2+, Ni2+, Cr3+, Mo4+, Mo5+, and Mo6+. Chromium is enriched and cobalt and nickel are depleted in the oxide; however, nickel is enriched and cobalt is depleted in the substrate alloy just under the surface oxide film. Concentration of chromium was low and that of nickel was high at small take-off angles. This indicates that distribution of chromium is greater in the inner layer, but nickel is distributed more in the outer layer of the surface oxide film. During immersion in Hanks’ solution, cobalt and nickel dissolved, and the film composition changed to mostly chromium oxide (Cr3+), along with small amounts of cobalt, nickel, and molybdenum oxides, and calcium phosphate containing magnesium, potassium, and carbonate. After immersion in Hanks’ solution, the thickness of the surface layer containing calcium phosphate increased to more than 4nm, while the amount of OH− increased. The amount of cobalt and nickel in the surface oxide film and in the substrate alloy just below the oxide decreased during immersion.

A 25-year laboratory experiment on French SON68 nuclear glass leached in a granitic environment – First investigations

We have investigated a 25.75-year old leaching experiment to improve our understanding of the mechanisms controlling glass dissolution in geological disposal conditions. A SON68 glass block was leached in slowly renewed synthetic groundwater (at 90 °C, 100 bar) in contact with some pieces of granite and Ni–Cr–Mo alloy as environmental storage materials. One hundred and sixty-three samplings were carried out over the entire duration of the experiment and were used to calculate the mean thickness of the altered glass (28 (±9) μm) and the glass dissolution rate. After few months, the rate remained very constant at 6 × 10 −3 g m −2 d −1 which is about 20 times higher than the residual rate measured in a batch reactor at the same temperature. At the end of the experiment, mainly SEM analyses were performed on the entire glass block. Surprisingly, the glass alteration layer has neither a homogeneous thickness, nor a homogeneous morphology. The location of the sampling valve (at half height of the glass block) seems to divide the glass block into two parts. In the upper half (above the sampling valve), the general morphology of the alteration layer consists in a relatively simple and uniform gel and some secondary phases which are rare-earth phosphates. The mean measured thickness of this alteration layer is 6.7 (±0.3) μm. However, in the lower half of the glass block, the gel is globally larger and frequently contains rounded shapes which are rare-earth phosphates. This section is edged by secondary phases bearing Mg, Na, Zn and Ni. The mean measured thickness is 81.3 (±1.1) μm in the lower half. In this experiment, the flow rate which leads to the hydrodynamic transport of the soluble species must be a key factor for the local glass alteration process. We have also shown that this unexpected behavior is likely due to heterogeneities of the chemistry of the solution. This conclusion is supported by the behavior of Mg. This element, supplied by the inlet solution, precipitates with Si and forms clay minerals and therefore weakens the passivating properties of the gel. Mg-rich clay minerals are only observed in the lower half of the glass block. Further investigations are necessary to better understand the coupling between the hydrodynamics and chemistry in this experiment. However, based on this study, we can conclude that glass in disposal should be very sensitive to the water renewal near the glass surface.

Characterization of dental metal–ceramic interfaces immersed in artificial saliva after substructural mechanical metallization with titanium

The purpose of this study was to analyze the mechanical strength and microstructure of dental metal–ceramic interfaces immersed in acidic artificial saliva after mechanical metallization of a NiCr-based substrate. Commercial NiCrMo alloy and dental porcelain were characterized before the production of metal–ceramic specimens. Therefore, a group of metallic surfaces was mechanically metallized with Ti. After that, metal–ceramic interfaces were produced and immersed in an electrochemical cell containing artificial saliva. In order to accelerate the corrosion of the interfaces, a potential of 0.75 V was applied on the metallic substrate for 30 min. 3-point bending tests of the metal–ceramic systems were carried out according to the ISO-9693 standard before and after immersion tests. The metallic surfaces as well as the metal–ceramic interfaces were analyzed by SEM–EDS. There was a decrease of the mechanical strength of conventional metal–ceramic interface after immersion. However, the mechanical strength of the samples with metallized interfaces remained unaltered after immersion in artificial saliva.

Microstructure and anti-oxidation behavior of laser clad Ni–20Cr coating on molybdenum surface

A Ni–20Cr coating was deposited on a molybdenum substrate by laser cladding. The observation of the microstructure by SEM demonstrates that the coating is free of cracks and pores, and metallurgically bonded to the substrate. XRD and EDS analysis results show that some dilution occurs at the coating/substrate interface and that Mo combines with Ni–20Cr, to form a Ni–Cr–Mo alloy coating with slight oxidation. The oxidation behavior of the coating indicates that the laser clad Ni–20Cr coating can effectively prevent oxidation of molybdenum at 600 °C in air. The oxide scale formed on the coating surface by oxidation in air is composed of NiO, Cr 2O 3 and NiMoO 4.

Microstructure stability and mechanical properties of an age-hardenable Ni–Mo–Cr alloy subjected to long-term exposure to elevated temperature

This paper characterizes the microstructure and mechanical properties of a nickel-based superalloy with a nominal composition of Ni–25Mo–8Cr (wt.%) after long-term exposures to elevated temperatures. The alloy is strengthened by long-range-ordered precipitates of an o I6 metastable phase with the Ni 2(Mo,Cr) stoichiometry. The alloy was annealed at 650 °C for 1000, 2000 and 4000 h, after it had been plastically deformed in order to accelerate diffusion processes occurring at elevated temperature and consequently to ease the formation of stable phases. The microstructure was characterized using TEM, SEM and X-ray phase analyses; mechanical properties were measured in tensile tests. It has been determined that the alloy loses its phase stability upon plastic deformation and subsequent long-term annealing at 650 °C. The microstructure, composed initially of a dispersed Ni 2(Mo,Cr) strengthening phase in a Ni-based solid solution, decomposes during annealing into a mixture of Ni 3Mo- and Ni 4Mo-type phases, Mo-lean Ni-based solid solution and a complex intermetallic P phase. The dominant new phase is a plate-shaped Ni 3Mo-type phase while the P phase appears as singular small precipitates. The Ni 3Mo phase is formed mainly in regions of highly localized deformation, e.g., in shear bands, and only occasionally nucleates in regions where the deformation was relatively uniform (dislocations or twins in one system). Regions adjacent to the plates of the Ni 3Mo phase are recrystallized and free from an Ni 2(Mo,Cr) strengthening phase. Changes in microstructure of the deformed alloy during long time annealing at 650 °C result in the decrease in the yield strength as well as tensile elongation at both room temperature and 650 °C. A significant decrease in elongation at 650 °C occurs only in specimens tested in air but not those tested in vacuum.

The influence of opaque application methods on the bond strength and final shade of PFM restorations

Objectives The aim of this study is to compare the influence of the opaque application method on the adhesion and final shade of porcelain-fused-to-metal restorations. Methods Four samples ( n = 12) were cast in a NiCrMo alloy and opaqued using three application methods: aerosol-spray (one application), aerosol-spray (two applications), paste and powder–liquid prior to veneering with dentine porcelain to a thickness of 1.0 mm to mimic the clinical thickness of porcelain-fused-to-metal crowns. The porcelain to metal adhesion was determined by measuring the interfacial fracture toughness or strain energy release rate with a four-point bending configuration developed by Charalambides et al., 13 at a loading rate of 0.05 mm min −1 in kerosene. The resultant porcelain shade was measured with a spectrophotometer under daylight. Values of L*, a* and b* were used to calculate the total color difference Δ E with different equations CIELAB, CMC(1:1), CIE94, and CIEDE2000. The resulting values were also compared with a reference unbonded sample made from the same dentine porcelain used to veneer the porcelain-fused-to-metal specimens. Results The application technique of the opaque did not influence the adhesion between the porcelain and metal. All the application methods demonstrated brittle cracking behaviour through the opaque layer. No visible color differences were found between the applications methods in the final shade of the porcelain. Significance The application method in terms of bond strength and final porcelain shade is not a factor in choosing which method to use in the dental laboratory.

Radially arrayed nanopillar formation on metallic stent wire surface via radio-frequency plasma

MP35N (Co–Ni–Cr–Mo alloy) is an important stent implant material for which many aspects, that include nanostructured surfaces, are yet to be understood. The present study provides the first creation of radially emanating metallic nanopillar structures on the surface of MP35N stent alloy wires; a novel textured surface structuring derived via controlled RF processing technique. The goal of this study was to characterize the newly found structures, identify evolution stages of nanopillar formations, as well as optimize RF process parameters for controlled surface texturing technique for stent wire materials. The exposure of a stent alloy wire, 250 μm diameter Co–Ni–Cr–Mo alloy (MP35N), to parameter-controlled RF environment resulted in dense surface nanostructures consisting of high-aspect-ratio dendritic nanopillars/nanowires. Extensive surface characterization and local compositional analyses by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS) show increased values of Mo contents on the outer edges of protruding nanopillars, indicating a possibility of the higher Mo content phase contributing to the differential plasma sputter etching on the MP35N surface and resultant nanowire formation. A comparative investigation on single phase alloy versus multi-phase alloy seems to point to the importance of phase segregation for successful nanowire formation by RF plasma treatment. In addition to MP35N, some specific single phased materials, such as Fe–Ni and Fe–Cr alloys or Pt metal wire, were exposed in same RF plasma conditions and results did not form the complex structures found on MP35N samples. For the purpose of this study, metallic stent wires that have nanostructured surfaces can be considered a “polymer-less” approach to surface modification, The creation and characterization of radially arrayed nanostructured surfaces has been demonstrated on MP35N stent alloy wires using this RF plasma process; where such nanostructured surfaces contribute to design concepts that may enhance endotheliazation of stent materials via surface texturing modification.

Passivation and Depassivation of Alloy 22 in Acidic Chloride Solutions

Alloy 22 (N06022) is a Ni–Cr–Mo alloy that offers an outstanding corrosion resistance in a wide variety of highly corrosive environments. In the present work, the general corrosion of alloy 22 in the passive and active states and the transition from passive and active states were studied in acidic chloride solutions at . Electrochemical studies, including electrochemical impedance spectroscopy and polarization tests, were performed using mill-annealed and thermally aged (10 h at ) alloy 22 specimens. The depassivation pH was 1.7 in deaerated conditions and in aerated conditions. The transition from passive to active states was characterized by a 3 orders of magnitude increase in the corrosion rate (CR) and a significant increase in the interfacial capacity. The CRs obtained via electrochemical tests for mill-annealed (MA) and thermally aged alloy 22 were comparable in all the tested conditions used in the present work. Intergranular attack was observed in thermally aged alloy 22 corroding in the active state due to the presence of precipitates and adjacent depleted zones of the protective alloying elements.

Oxidation Behavior and Electrical Property of a Ni-Based Alloy in SOFC Anode Environment

The oxidation behavior and electrical property of a Ni–Mo–Cr alloy at in a simulated solid oxide fuel cell (SOFC) anode environment (humidified and diluted ) have been studied. The thermally grown oxide scale presents a multilayered structure, which is similar to that formed in air, with densely grown in between an underneath layer of the intermetallic compound and a less compact top layer consisting of with flakes embedded. The oxidation kinetics obey a two-stage parabolic law with an initially fast oxidation (0–170 h at a rate of ) followed by a slower steady oxidation (170–1000 h at a rate of ). The reducing atmosphere, even with a significantly lower oxygen partial pressure, has a negative effect on the high temperature oxidation resistance; however, it enhances the adherence of the scale to the substrate. The outward diffusion of Ti ions changes the composition, lattice parameters, and diffraction peak positions of the formed oxides, leading to Ti-doped and the spinel. The area specific resistance of the oxide scale preformed at for 1000 h is at , which is higher than that formed in air and lower than that of other studied Ni-based alloys.

Interaction between (La, Sr)MnO3 cathode and Ni–Mo–Cr metallic interconnect with suppressed chromium vaporization for solid oxide fuel cells

Abstract Interaction between (La0.8Sr0.2)0.90MnO3 (LSM) cathode and newly developed Ni–Mo–Cr metallic interconnect is investigated at 900 °C under operation conditions of solid oxide fuel cells (SOFCs). The results show that chromium deposition on the LSM cathodes in the presence of Ni–Mo–Cr interconnect is remarkably reduced as compared to that in the presence of a conventional Fe–Cr metallic interconnect (RA446). In contact with the Ni–Mo-Cr interconnect the overpotential, η, for the O2 reduction reaction on LSM cathode decreased from 529 to 111 mV during the 1200 min current passage at 200 mA/cm2. In contrast, η increased from 464 to 561 mV for the reaction in the presence of a RA446 interconnect. The decrease in η clearly indicates that chromium poisoning effect of the Ni–Mo–Cr interconnect is also significantly suppressed as compared to that with conventional Fe–Cr interconnect materials. The suppressed Cr deposition and poisoning effects observed on the LSM cathodes demonstrate promising potential of the Ni–Mo–Cr alloy as new interconnect materials with significant suppressed chromium vaporization and deposition for SOFCs.

Visualisation of the local electrochemical activity of thermal sprayed anti-corrosion coatings using scanning electrochemical microscopy

Scanning electrochemical microscopy was used to study the electrochemical activity of anti-corrosion coatings formed from Inconel 625, a Ni–Cr–Mo alloy commonly used in engineering applications. The coatings were formed using a high velocity oxygen fuel thermal spraying technique. Upon spraying the alloy onto mild steel substrates, clear splat boundaries were formed at the interface between adjacent droplets as they cooled on the substrate surface. Scanning electrochemical microscopy in the feedback mode, employing ferrocenemethanol as redox mediator, was used to study the local electrochemical activity of samples of the wrought alloy, the sintered alloy and the thermal sprayed coating. The wrought and sintered materials showed responses typical of that expected for a purely insulating material. However, SECM approach curve data showed that the electrochemical activity of the thermal sprayed material was higher than that of the bulk alloy. Local variations in the coating's electrochemical activity were then visualised using SECM imaging, which appear to be related to the splat boundaries formed during the thermal spray process.

Investigation of the metal/porcelain interface in LASER-welded Ni–Cr–Mo alloyArticle based on a version presented at the XXXII CONSOLDA, Belo Horizonte, Minas Gerais, Brazil, 2–5 October 2006.

The interface formed between the metal and the porcelain of laser-welded Ni–Cr–Mo alloy was studied on a metallurgical basis. The characterization was carried out by using optical microscope, electron scan microscopy and X-ray dispersive spectroscopy techniques and mechanical three-point flexion tests, in the laser-welded region, with and without porcelain. The union of the porcelain with the alloy is possible only after the oxidation of the metallic surface and the subsequent application of a bonding agent known as opaque. The porcelain applied to the base metal and weld bead showed different behaviours – after the flexion test, the base metal showed cracks, while that in the weld bead broke away completely. It was noted that the region subjected to laser welding had lower adherence to the porcelain than the base metal region, due to microstructural refinement of the weld bead. These results can be shown by the X-ray dispersive spectroscopy carried out on the regions studied. The flexion tests demonstrated that the Ni–Cr–Mo alloy subject to laser welding had significant alterations in its mechanical properties after application of the porcelain.

Ni–Mo–Cr alloy for Interconnect Applications in Intermediate Temperature Solid Oxide Fuel Cells

As part of an effort to develop robust metallic interconnects for intermediate temperature solid oxide fuel cells, a Ni–Mo–Cr alloy is designed, prepared, and investigated in terms of its microstructure, mechanical property, thermal expansion behavior, oxidation resistance, and electrical property. The developed Ni–Mo–Cr alloy possesses a good thermal expansion compatibility with cell components with a coefficient of thermal expansion smaller than at temperature below . Upon oxidation at in air, the oxide scale consisted of two kinds of oxide with densely packed and Cr-free on top of continuous , and intermetallic compound layer is formed underneath the oxide scale. Two stages of parabolic oxidation kinetics are observed with oxidation rate decrease after of oxidation, and good thermal cyclicability of the oxide scale is demonstrated. The area-specific resistance (ASR) as a function of oxidation time shows the similar tendency to the oxidation weight gain, giving an ASR at of for oxidation at in air for and an extrapolated ASR of for oxidation.

Influence of Gd and B on solidification behaviour and weldability of Ni–Cr–Mo alloy

The influence of Gd and B on the solidification behaviour and weldability of Ni–Cr–Mo alloy UNS N06455 has been investigated by Varestraint testing, differential thermal analysis and microstructural characterisation. These alloys are currently being developed as structural materials for nuclear criticality control in applications requiring transportation and disposition of spent nuclear fuel owned by the US Department of Energy. The Gd containing alloys were observed to solidify in a manner similar to a binary eutectic system. Solidification initiated with a primary L→y reaction and terminated at ~1258°C with a eutectic type L→y+Ni5Gd reaction. The solidification cracking susceptibility of the Gd containing alloys reached a maximum at ~1 wt-%Gd and decreased with both higher and lower Gd additions. Low cracking susceptibility at Gd concentrations below ~1 wt-% was attributed to a relatively small amount of terminal liquid that existed over much of the crack susceptible solid+liquid zone. Low cracking susceptibility at Gd concentrations above ~1 wt-% was attributed to a reduced solidification temperature range and backfilling of solidification cracks. The addition of B above the 230 ppm level leads to the formation of an additional eutectic type reaction at ~1200°C and the secondary phase within the eutectic type constituent was tentatively identified as Mo3B2. The B containing alloys exhibited a three step solidification reaction sequence consisting of primary L→y solidification, followed by the eutectic type L→y+Ni5Gd reaction, followed by the terminal eutectic type L→y+Mo3B2 reaction. Boron additions had a strong, deleterious influence on solidification cracking susceptibility. The high cracking susceptibility was attributed to extension of the crack susceptible solid+liquid zone induced by the additional eutectic type L→y+Mo3B2 reaction and extensive wetting of the grain boundaries by the solute rich liquid. Simple heat flow equations were combined with solidification theory to develop a relation between the fraction liquid fL and distance x within the solid+liquid zone. Information on the phenomenology of crack formation in the Varestraint test were coupled with the calculated fL–x curves and were shown to provide useful insight into composition–solidification–weldability relations.