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David Pacheco
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Blog's And Portfolio
Blog
Restoration of Antique Sewing Machine
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18 Feb 18
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Restoration of old sewing machines requires talents and mechanic skills because several parts need...
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Fatigue Tension Test at -196° C - Fatigue Specimen
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26 Sep 17
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Austenitic Stainless steel AISI 316; Frequency of 120 Hz; 30 million cycles; Stages I and II of...
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Mig Aluminum - Welder Qualification Test
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26 Sep 17
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Aluminum alloy. Mig welding parameters and procedures defined before the qualification test. After...
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Gas Bottle - Submerged-Arc Welding -
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26 Sep 17
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Low carbon steel AISI 1008. Corrections of the welding parameters with improvements: full...
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24 Sep 17
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I trained and qualified 65 Mig / Mag welders. In the photo a Mig welder performs a weld bead in the...
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Sludge Pump Casing - Cast Steel
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24 Sep 17
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As-cast structure; Low carbon steel; Coarse grains of alpha ferrite and fine pearlite. Fracture of...
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Carbon Steel AISI 1008 - Thin Sheet - Static Aging
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23 Sep 17
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Static aging after rolling of the thin sheet. Alpha ferrite matrix; Grain growth; Precipitates in...
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23 Sep 17
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On the right of the photo, thin sheets removed from the tank by oxyacetylene cutting. On the left,...
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Failure Analysis - Dental Instrument
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22 Sep 17
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New and unused dental instrument; Martensitic stainless steel AISI 416; Forging defects: aligned...
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Maintenance Failure - Abrasive Wear
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22 Sep 17
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Maintenance failure -Abrasive wear. Mechanical Press Shaft: Damaged ball bearing caused abrasive...
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22 Sep 17
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Typical micrograph: HAZ with unmodified grains and others recrystallized after TIG welding;...
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Simple Illustration - Epsilon Martensite
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13 Sep 17
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Austenitic stainless steel AISI 304 (thin sheet). Left on photo steel as received; Austenite matrix...
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Quality Control - Low-Carbon Filler Wire (3,18 mm) - Submerged-Arc Welding
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03 Apr 16
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High strain hardening: deformed and flattened grains of alpha ferrite. Welding defects: arc...
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Marine Corrosion (Test) - Aluminum AA 5053
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03 Apr 16
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Surface corrosion (pitting) and intergranular precipitation.
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All-Welded Steel Construction - Diesel Tank
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18 Mar 16
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Steel ASTM A285C; MMA welding; shielded electrode E7018G.
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Quality Control - Metallurgical Analysis - Blanking Die
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18 Mar 16
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Blanking die. Tool steel AISI D3: wrong oil quenching and tempering; carbide bands. Low hardness:...
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Fatigue Tension Test - David's Mechanism - MSc Thesis
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16 Mar 16
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Tension test at -196°C (liquid nitrogen); 30 millions of cycles; stainless steel AISI 316...
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Failure Analysis - Fatigue Fracture
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16 Mar 16
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Tugboat: shaft drive. David's Mechanism in practice. Martensitic stainless steel 17-4PH;...
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Failure Analysis - Fatigue Fracture
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16 Mar 16
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Air compressor: shaft drive. Low alloy steel SAE 4140; normalized; rough machining (keyway);...
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Quality Control - Failure Analysis - Resistance welding
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13 Mar 16
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Refrigerator (Condenser). Wrong welding parameters: excessive pressure and electric current;...
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Metallic Structure - Load Test
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12 Mar 16
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Unsteady metallic structure. Inadequate low-carbon steel AISI 1008; ferritic matrix.
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Quality Control - Metallurgical Analysis - Gas Brazing
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12 Mar 16
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Unqualified worker, wrong procedures. Defect: porosities (steam reaction); contaminated diffusion...
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Quality Control - Metallurgical Analysis - Low-carbon AISI 1008 "normalized"
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11 Mar 16
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Alpha ferrite: secondary recrystallization, grain growth, static aging and hardening. Application:...
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Failure Analysis - Hydrogen Embrittlement - Fatigue Fracture -
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11 Mar 16
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Crane runway: 50 fractured bolts. Microstructure: cubic and tetragonal martensite (incomplete...
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Quality Control - Metallurgical Analysis - Gray Cast Iron
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11 Mar 16
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Irregular microstructure: pearlite (dark), ferrite (white), flakes graphite type C and eutectic.
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Robotic Tig Welding - Washing Machine - Innovation
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10 Mar 16
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Industrial development. Tig welding without filler metal; dissimilar coatings.
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06 Mar 16
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Machining; Heat treating: stress relief, oil quenching, first tempering, subzero treatment at...
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Failure Analysis - Crane Runway
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02 Mar 16
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Welding defects: plates without chamfering; wrong parameters and procedures; low penetration of...
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Resistance Welding - Dissimilar Metals
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02 Mar 16
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Resistance welding without critical defects.
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Quality Control - Metallurgical Analysis - AISI 1080 Steel
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01 Mar 16
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Eutectoid structure: pearlitic matrix. Optical microscopy.
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Quality Control - Gas Brazing - Metallurgical Analysis
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01 Mar 16
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Gas brazing (Innovation): full capillarity without defects. Optical microscopy.
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Robotic Welding - Tig Process - Innovation
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29 Feb 16
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Robotic Tig without filler metal; fixed stick out; room temperature 22° to 31° C.
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Forged Bolts and Nuts - New Design
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29 Feb 16
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Steel AISI 4340. Heat treatments after forging: stress relief, oil-quenching and 2 tempering;...
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29 Feb 16
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Welded beads (SAW) and their scales. Scale 2: mechanical and metallurgical properties better than...
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Quality Control - Destructive Testing - Gas Brazing - Drier Filter
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28 Feb 16
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Picture enlarged.
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Quality Control - Metallurgical Analysis - Nodular Cast Iron -
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28 Feb 16
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Irregular graphite nodules; wrong inoculation.
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Quality Control - Brazing Filler Metal Ag 2%
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28 Feb 16
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Coarse cast matrix: dendritic structure.
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Fatigue Fractures - Tension Test - SS AISI 316
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28 Feb 16
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Surfaces: 1) Fragile - cleavage planes; 2) Ductile (final stage) - microvoids
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Quality Control - Refrigerator - Manufacturing Faults
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28 Feb 16
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The faults: gas brazing process; filler metal (Ag 14); brazing procedures; unskilled worker.
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Submerged Arc Welding (SAW) - Diffuser - Innovation
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27 Feb 16
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Diffuser stabilizes electric arc during welding and reduces 38% the temperature inside pistol-grip...
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27 Feb 16
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Fractures in operation - 20 finished parts. Bad heat treating: quenching effects without tempering...
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Pressure Vessel - Autoclave - Preventive Inspection
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27 Feb 16
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None previous inspections. Disposable equipment.
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Quality Control - Nondestructive Testing - Innovation
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26 Feb 16
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Condenser after test. No plastic deformation and cracks.
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Quality Control - Carbon steel AISI 1040 Oil Quench
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26 Feb 16
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Wrong heat treating: burned steel and very fragile; coarse martensite, cementite and alfa ferrite.
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Quality Control - Gas Brazing Test - Filler Metal Ag 25
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26 Feb 16
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Base metal Cu DHP. Fused metal: dendritic structure; diffusion zone without defects.
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26 Feb 16
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Trained and qualified welder. Low carbon thin sheets. Very low welding defects (0,05%).
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Steel Construction - Steam Boiler - MMA Welding
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26 Feb 16
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MMA electrode E7025G, all positions, post heating; trained and qualified welders. Low welding...
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Fatigue Slip Planes - SS AISI 316 - Tension Test - MSc Thesis
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26 Feb 16
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SS 316 "annealed"; 30 millions of cycles; slip planes; deformation twins, grain...
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Maintenance - Repair Welding -Driving Pinion
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26 Feb 16
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Maintenance welding: MMA electrode E7018, preheating and post heating. No distortion. Machining...
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Failure Analysis: Stress Corrosion Cracking - Naval brass - Innovation
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26 Feb 16
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Oil tanker: the first occurrence in service; naval brass condenser
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26 Feb 16
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Full corrective maintenance: diesel engine, pneumatic system, pneumatic clutch, hydraulic...
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Steel Construction - Diesel deflector - Innovation
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26 Feb 16
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New design; MMA welding, electrode E7018G; No preheating and post heating cycle; Back step...
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Quality Control - Destructive testing - Refrigerator - Innovation
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26 Feb 16
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Condenser and drier filter; Gas Brazing process; filler metal Ag 25; brazing joint without fracture...
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David's Mechanism of Fatigue Fracture - Innovation
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25 Feb 16
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Fatigue tension test; SS AISI 316; Room temperature (25° C); 30 million of cycles; Fracture...
- David Pacheco's portfolio and work achievements
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David Pacheco -
David's talents in the field of Welding, Mechanical Engineering, Creative Development, Vehicle Mechanic and others would soon be seen through work portfolios shared here. David would share files, the best presentation made or the work experience certificates.
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Blogs and Portfolios
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