Preliminary Investigation into Repair of High Strength Steel Using Laser Cladding

2010 ◽  
Vol 654-656 ◽  
pp. 362-365
Author(s):  
Reza Mohammed ◽  
Qian Chu Liu ◽  
Madabhushi Janardhana ◽  
Graham Clark
Keyword(s):  
Laser Cladding ◽  
Promising Result ◽  
Preliminary Investigation ◽  
High Strength Steels ◽  
High Strength ◽  
Critical Crack ◽  
Aerospace Applications ◽  
Aircraft Landing ◽  
Mass Flow Rates ◽  
Engine Components

High-strength steels are used in several critical aerospace applications such as aircraft landing gear, primary structure and engine components. These steels, such as the AISI 4340 assessed here exhibit small critical crack sizes, and when they suffer in-service damage from impact or corrosion, repairing the damage is particularly challenging. One potential repair method is using laser assisted metal deposition (LAMD or ‘laser cladding’ LC), to rebuild the damaged region or the grinding depression remaining after the damage has been removed. The critical situations where these materials are used makes it essential that repairs do not introduce any degradation, such as microcracking, that could lead to failure in service. In this trial, 420 grade stainless steel cladding powder was used to produce a clad layer with both high strength and good corrosion resistance. The cladding was performed under various powder mass flow rates, traverse speeds, and laser powers. The clad thickness and the depth of the fusion zone varied, as expected, with all the cladding conditions. It was found that there was very little porosity, and importantly, no evidence of microcracking under any cladding condition. There were some small defects near the clad boundary, apparently associated with each clad pass. The absence of microcracking is a promising result, and the research will be continued to assess the effect of microstructure and defects on performance of the repaired plates.

Characterization of a AISI/SAE 4340 Steel in Different Microstructural Conditions

2014 ◽  
Vol 775-776 ◽  
pp. 136-140 ◽  
Author(s):  
Renato Araujo Barros ◽  
Antonio Jorge Abdalla ◽  
Humberto Lopes Rodrigues ◽  
Marcelo dos Santos Pereira
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Aviation Industry ◽  
Sodium Metabisulfite ◽  
Aerospace Applications ◽  
Aircraft Landing ◽  
Aircraft Landing Gear ◽  
Structural Applications ◽  
Ultra High Strength Steels ◽  
Pin On Disk

The 4340 are classified as ultra-high strength steels used by the aviation industry and aerospace applications such as aircraft landing gear and several structural applications, usually in quenched and tempered condition. In this situation occurs reduction of toughness, which encourages the study of multiphasic and bainític structures, in order to maintain strength without loss of toughness. In this study, ferritic-pearlitic structure was compared to bainitic and martensitic structure, identified by the reagents Nital, LePera and Sodium Metabisulfite. Sliding wear tests of the type pin-on-disk were realized and the results related to the microstructure of these materials and also to their hardnesses. It is noted that these different microstructures had very similar behavior, concluding that all three tested pairs can be used according to the request level.

Applying Gurson Type of Damage Models to Low Constraint Tests of High Strength Steels and Welds

2006 ◽  
Author(s):  
Ming Liu ◽  
Yong-Yi Wang
Keyword(s):  
Damage Mechanics ◽  
Ductile Failure ◽  
High Strength Steels ◽  
High Strength ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Critical Crack ◽  
Gtn Model ◽  
Strain Capacity ◽  
Low Constraint

Pipelines experiencing displacement-controlled loading need to have adequate strain capacity. Large tensile strain capacity can only be achieved when the failure processes are ductile. In ductile failure analyses, the strain capacity may be determined by two approaches. The first approach uses the conventional fracture mechanics criteria, such as the attainment of the critical crack tip opening displacement, to assess the onset of the crack propagation. The other approach uses damage mechanics models in which the onset and propagation of cracks are controlled by the nucleation, growth, and coalescence of voids in the material. The damage mechanics models can provide some insights of the ductile failure processes as they have more physical mechanisms built in the constitutive model. In this paper, the Gurson-Tvergaard-Needleman (GTN) model is applied to two types of low-constraint tests: curved wide plates and back-bend specimens. The wide plate test is considered more representatives of full-scale pipes than the conventional laboratory-sized specimens, but requires large-capacity machines. The back-bend test is a newly developed low-constraint laboratory-sized test specimen. A relatively simple approach to determine the damage parameters of the GTN model is discussed and the transferability of damage parameters between those two test types is also analyzed.

Microstructures and Mechanical Properties of 30CrMnSiA and 30CrMnSiNi2A High-Strength Steels After Laser-Cladding Repair

2020 ◽  
Vol 47 (11) ◽  
pp. 1102002
Author(s):  
庞小通 Pang Xiaotong ◽  
龚群甫 Gong Qunfu ◽  
王志杰 Wang Zhijie ◽  
李铸国 Li Zhuguo ◽  
姚成武 Yao Chengwu
Keyword(s):  
Mechanical Properties ◽  
Laser Cladding ◽  
High Strength Steels ◽  
High Strength ◽  
Microstructures And Mechanical Properties

Influence of Predetermined Surface Defect to the Bendability of Ultra-High-Strength Steel

2012 ◽  
Vol 504-506 ◽  
pp. 901-906 ◽  
Author(s):  
Antti Määttä ◽  
Antti Järvenpää ◽  
Matias Jaskari ◽  
Kari Mäntyjärvi ◽  
Jussi A. Karjalainen
Keyword(s):  
Surface Defects ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Crack Size ◽  
Critical Crack ◽  
Bending Radius ◽  
Ultra High Strength Steels ◽  
Materials Used ◽  
Critical Crack Size

The use of ultra-high-strength steels (UHS) has become more and more popular within last decade. Higher strength levels provide lighter and more robust steel structures, but UHS-steels are also more sensitive to surface defects (e.g. scratches). Practically this means that the critical crack size decreases when the strength increases. The aim of the study was to study if the formula of critical crack size is valid on forming processes of UHS-steels. Surface cracks with different depths were created by scratching the surface of the sheet by machining center. Effect of the scratch depth was determined by bending the specimens to 90 degrees. Bents were then visually compared and classified by the minimum achieved bending radius. Test materials used were direct quenched (DQ) bainitic-martensitic UHS steels (YS/TS 960/1000 and 1100/1250). Results from the bending tests were compared to the calculated values given by the formula of critical crack size.

Characterization of Additive Manufactured Inconel 718 Alloy Using Laser Cladding

2021 ◽  
Vol 882 ◽  
pp. 3-10
Author(s):  
Prayag Burad ◽  
G. Chaitanya ◽  
Nikhil Thawari ◽  
Jatin Bhatt ◽  
T.V.K. Gupta
Keyword(s):  
Laser Cladding ◽  
Inconel 718 ◽  
Elevated Temperatures ◽  
High Strength ◽  
Inconel 718 Alloy ◽  
Powder Morphology ◽  
Material Deposition ◽  
Layer Deposition ◽  
Engine Components

Laser based metal additive manufacturing (AM) is an emerging technology in various aerospace industries including aero-engine components and turbine manufactures. Laser cladding is a potential process for material deposition and surface enhancement technique that forms a strong metallurgical bond with the substrate. In the present study, Nickel based Inconel 718 (IN718) super alloy which maintains high strength working at elevated temperatures is used as the clad material. The study investigates the processing of Inconel 718 with powder morphology and microstructural properties and also two, three and four-layer deposition. This study explores the possibility of depositing IN718 using laser cladding that can be better considered as metal AM process.

Genetic Alloy Design of Ultra High Strength Stainless Steels: From Thermodynamics to Quantum Mechanics

2010 ◽  
Vol 638-642 ◽  
pp. 3473-3478
Author(s):  
Pedro E.J. Rivera-Díaz-del-Castillo ◽  
Wei Xu ◽  
Sybrand van der Zwaag
Keyword(s):  
Stainless Steels ◽  
Lath Martensite ◽  
High Strength Steels ◽  
High Strength ◽  
Alloy Design ◽  
Processing Route ◽  
Cohesion Energy ◽  
Aerospace Applications ◽  
Ultra High Strength Steels ◽  
Corrosive Environments

The design of novel ultra high strength steels for aerospace applications is subjected to stringent requirements to ensure their performance. Such requirements include the ability to withstand high loads in corrosive environments subjected to temperature variations and cyclic loading. Achieving the desired performance demands microstructural control at various scales; e.g. fine lath martensite is desired in combination with nanoprecipitate networks at specified volume fractions, and controlled concentrations of alloying elements to prevent alloy embrittlement. The design for a specified microstructure cannot be separated from the processing route required for its fabrication. Alloys displaying exceptional properties are subjected to complex interactions between microstructure and processing requirements, which can be described in terms of evolutionary principles. The present work shows how genetic alloy design principles have been utilised for designing stainless steels displaying strength exceeding that of commercial counterparts. Such designed alloys become feasible for fabrication by tailoring their microstructure employing thermodynamic and kinetic principles, while fracture toughness properties can be controlled via performing quantum mechanical cohesion energy computations.

High Strain Rate Fracture Properties of High Strength Steels and Their Application

2011 ◽  
Author(s):  
Alan M. Clayton ◽  
John Dabinett
Keyword(s):  
Strain Rate ◽  
High Strain ◽  
Cast Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Crack Size ◽  
Strength Properties ◽  
Strain Rates ◽  
Critical Crack ◽  
Welded Steel

The evaluation of fracture of ferritic steels using the methods in ASME Code Case 2564 for impulsively loaded vessels requires the static reference temperature T0 and the upper shelf toughness, and these are used together with the Master Curve to define the transition temperature curve. The effect of high rates of strain on the ductile-brittle transition is determined in the code case using a correlation due to Wallin. Two steels used for impulsively loaded vessels, welded steel similar to HY80 plate and a cast steel similar to HY100 have been evaluated to obtain their static fracture and strength properties. Additional instrumented pre-cracked Charpy testing using a draft ISO standard has determined the shift in T0 with high strain rates and the results have been compared to the Wallin correlation. The strain rate correlation is used to evaluate the fracture response of vessels made of these steels when subjected to internal blast. By using the instantaneous strain rates of the vessel wall vibration considerable gains in critical crack size can be obtained compared to using the highest rate throughout the whole of the transient.

Physical, Chemical, and Crystallographic Characterization of Anodic Coatings on High Strength Aluminum Base Alloys

1976 ◽  
Vol 34 ◽  
pp. 636-637
Author(s):  
R. E. Herfert ◽  
N. T. McDevitt
Keyword(s):  
Sulfuric Acid ◽  
Salt Spray ◽  
High Strength ◽  
Environmental Stability ◽  
Anodic Films ◽  
Sodium Dichromate ◽  
Corrosion Resistant ◽  
Aerospace Applications ◽  
Bond Strengths ◽  
Adhesive Bonded Joints

Durability of adhesive bonded joints in moisture and salt spray environments is essential to USAF aircraft. Structural bonding technology for aerospace applications has depended for many years on the preparation of aluminum surfaces by a sulfuric acid/sodium dichromate (FPL etch) treatment. Recently, specific thin film anodizing techniques, phosphoric acid, and chromic acid anodizing have been developed which not only provide good initial bond strengths but vastly improved environmental durability. These thin anodic films are in contrast to the commonly used thick anodic films such as the sulfuric acid or "hard" sulfuric acid anodic films which are highly corrosion resistant in themselves, but which do not provide good initial bond strengths, particularly in low temperature peel.The objective of this study was to determine the characteristics of anodic films on aluminum alloys that make them corrosion resistant. The chemical composition, physical morphology and structure, and mechanical properties of the thin oxide films were to be defined and correlated with the environmental stability of these surfaces in humidity and salt spray. It is anticipated that anodic film characteristics and corrosion resistance will vary with the anodizing processing conditions.

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