Failure Beneath Cannon Thermal Barrier Coatings by Hydrogen Cracking; Mechanisms and Modeling

Underwood, J. H.; Vigilante, G. N.; Troiano, Edward

doi:10.1520/stp11071s

Cited by 3 publications

(4 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The value of SR is determined using the linear unloading concept, in which a residual stress is created by a virtual unloading from a calculated elastic applied sti-ess (tiiermal in tiiis case) tiiat is envisioned to be above tiie yield level of tiie material. The residual stress is of opposite sense to the applied stiress and of a value equal to tiie difference between tiie applied stress and the yield stirengtii, as shown by equation (2).…”

Section: Substrate Damage Model and Resultsmentioning

confidence: 99%

“…This consistency check, along with the validation by steel transformation results, gives confidence in the use of model temperatures for calculating stresses, discussed next. Near-bore temperatures were used to calculate the significant compressive transient stresses for tube #12, and from these stresses, the tensile residual stresses, as outlined by equations (1) and (2). Tensile residual stress results for each of the time durations, 4.1-and 9.5-ms, and their respective gas temperatures, 2490 and 1740°K, are shown in Figure 3.…”

Section: Substrate Damage Model and Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Thermal Damage, Cracking and Rapid Erosion of Cannon Bore Coatings

Underwood¹,

Parker

Vigilante³

et al. 2003

Journal of Pressure Vessel Technology

View full text Add to dashboard Cite

Thermal damage observed at the bore of fired cannons has increased noticeably in the past decade, due to the use of higher combustion gas temperatures for improved cannon performance. Current authors and coworkers recently have described cannon firing damage and proposed new thermo-mechanical models to gain understanding of its causes, with emphasis on the severe damage that occurs in the steel beneath the chromium plating used to protect the cannon bore. Recent refinements in the models will be used here to characterize some additional damage observations in the area beneath the protective coating of fired cannons. Model results validated by microstructural observations give predictions of near-bore temperature and stress distributions and good agreement with observed depths of hydrogen cracking in the high strength steel substrate. Interest in damage and failure within a coating is also of concern for cannons, since coating failure leads to extremely rapid erosion of coating and substrate. The slip zone model of Evans and Hutchinson is adapted here to predict failure strength of cannon coatings based on observed crack spacing and microhardness of thermally damaged areas. Results are described for electroplated chromium coatings from fired cannons and for sputtered chromium and tantalum coatings with laser-heating damage to simulate firing. Coating mechanics analysis of fired and laser-heated samples provides an insitu measurement of coating failure strength, showing that sputtered chromium has more than twice the failure strength of electroplated chromium. An analysis of cyclic shear failure of a coating interface at an open crack shows a six-fold decrease in low cycle fatigue life compared to the life of a closed crack. Recommendations are given for preventing rapid coating failure and catastrophic erosion of fired cannon, with emphasis on methods to prevent deep, open cracks in coating and substrate.

show abstract

Section: Substrate Damage Model and Resultsmentioning

confidence: 99%

Section: Substrate Damage Model and Resultsmentioning

confidence: 99%

Thermal Damage, Cracking and Rapid Erosion of Cannon Bore Coatings

Underwood¹,

Parker

Vigilante³

et al. 2003

Journal of Pressure Vessel Technology

View full text Add to dashboard Cite

show abstract

“…According to one of the leading authorities on gun tube failure mechanisms [1], circumferential-radial cracks, which grow in the plane normal to the circumferential=hoop stress, tend to propagate because of the dominant hoop-stresses. While longitudinal-radial stresses also may occur in practice due to a number of factors including curvature effects [2], an analysis of scanning electron microscope (SEM) images led to a belief of a thermal expansionresidual and stress-environmental cracking scenario.…”

Section: Introductionmentioning

confidence: 99%

“…Using this information, Underwood and co-workers [1,[3][4][5][6][7][8][9]] developed a thermomechanical model which used the finite difference method to first evaluate the transient temperature distributions as a function of the depth for a coated steel plate; the temperature calculations were done using boundary condition measurements from bore locations where the heat transfer was the most severe. For the model, linearly temperature dependent material properties were used to account for the wide temperature range that the coating and steel substrate experienced.…”

Section: Introductionmentioning

confidence: 99%

Severe Thermal and Pressure Transients and the Survival of Internally Coated Tubes with Interface Defects

Harris

Segall

Carter

2012

Materials and Manufacturing Processes

View full text Add to dashboard Cite

The effects of severe thermal and pressure transient pulses on the interior of coated tubes with known defects (cracks and blisters) have been analyzed using finite-element methods. For the modeling, both axisymmetric and three-dimensional (3-D) meshes were developed and used to assess the transient thermal-and stress-states and the propensity for fracture related damage. For all calculations, temperature dependent thermophysical and elastic properties were used during the analysis. The model also utilized uniform heating and pressure across the ID surface imposed via convective coefficients and a piece-wise linear pressure function. Results indicated that both had a significant influence on the maximum circumferential (hoop) stresses and temperatures and that the compressive thermal stresses help to offset the tensile stresses generated by the pressure. Calculations also looked into the influence of these factors when a cracks and/or blister defect was introduced at the interface of the coating and substrate with and without pressure.

show abstract