Industrial processes ii inden 3313
This presentation is the property of its rightful owner.
Sponsored Links
1 / 39

INDUSTRIAL PROCESSES II INDEN 3313 PowerPoint PPT Presentation


  • 118 Views
  • Uploaded on
  • Presentation posted in: General

INDUSTRIAL PROCESSES II INDEN 3313. Lecture 5 --Introduction to Joining Processes, Welding Metallurgy, Combustion and Electrical Welding Processes. OVERVIEW. Introduction to Welding Welding Metallurgy Welding Processes Combustion Processes. QUESTIONS TO START ??. INTRODUCTION TO JOINING.

Download Presentation

INDUSTRIAL PROCESSES II INDEN 3313

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Industrial processes ii inden 3313

INDUSTRIAL PROCESSES IIINDEN 3313

Lecture 5 --Introduction to Joining Processes, Welding Metallurgy, Combustion and Electrical Welding Processes

Industrial Processes II


Overview

OVERVIEW

  • Introduction to Welding

  • Welding Metallurgy

  • Welding Processes

    • Combustion Processes

Industrial Processes II


Questions to start

QUESTIONSTO START ??

Industrial Processes II


Introduction to joining

INTRODUCTION TO JOINING

  • Definition

    • “Joining is an all-inclusive term, covering processes such as welding, brazing, soldering, adhesive bonding, and mechanical fastening”. [Kalpakjian, p. 855]

  • Why Used?

    • Difficult/Impossible to Manufacture as a Single Piece

    • Easier/More Economical to Manufacture as Components and then Assemble Either In-Plant, On-Site, or By Customer.

    • (May) Allow Disassembly for Maintenance/Repair

    • Different Components Enable Different Properties at Different Places on Assemble (e.g., Wear Surfaces)

Industrial Processes II


Introduction to joining processes

INTRODUCTION TO JOINING PROCESSES

  • Welding (Definitions)

    • Metal Joining Process in Which Coalescence is Obtained Using Heat and/or Pressure

      • Coalescence - (From The Random House Dictionary)

        • 1. to grow together or into one body 2. to unite so as to form one mass, community, etc.; blend; fuse; join; 3. to cause to unite into one body. from the Latin “alere” meaning to grow.

    • A Metallurgical Bonding Accomplished by the Attracting Forces Between Atoms

    • Joining Two (or More) Pieces of Material by Applying Heat, Pressure, or Both, With or Without Filler Metal to Produce Localized Union Through Fusion or Recrystallization Across the Interface.

Industrial Processes II


Introduction to joining processes1

INTRODUCTION TO JOINING PROCESSES

  • Welding - Key Elements in Definitions

    • “Pieces of Material” -- Same Material Throughout

    • “Grow”, “Recrystallization” -- Grain Growth in Joint

    • “Localized Union” -- Restricted Area/Volume

      • Joint Types and Configurations

    • “Uses Heat and/or Pressure” -- Energy Required to Achieve Coalescence

      • This Provides Basis for Process Classification and Naming

      • Heat Sources -- Chemical, Electrical, Thermal, Mechanical

  • Why Use?

    • Strong, Permanent Joints

Industrial Processes II


Welding basic process

WELDING -- BASIC PROCESS

  • Part/Weld Function and Operating Environment is Defined

  • Type of Joint Selected/Analyzed

  • Component Parts Manufactured

  • Surfaces to Be Welded Are Cleaned

  • Components Are Aligned and Clamped

  • Non-Corrosive/Protective Environment Formed Around Area to Be Welded

Industrial Processes II


Welding basic process1

WELDING -- BASIC PROCESS

  • Heat and/or Pressure Applied to Components

  • Portion of Each Component Melts

    • Temperature of Fusion Reached, Maintained

    • Slag Produced

  • (Optional) Add Molten (Filler) Material

  • Heat From Process Affects Non-Melted Portion of Components

    • Grain Structure Affected

    • Expansion, Warping

    • Out Gassing, Corrosion

Industrial Processes II


Welding basic process2

WELDING -- BASIC PROCESS

  • Heat and/or Pressure Removed

  • Molten Material Begins to Solidify

    • Coalescence/Grain Formation

      • Size, Shape, Strength Function of Cooling Rate

    • Dissolved Gases Evolve

      • Out Gassing,

    • Shrinkage/Expansion of Weld Nugget Due to Change in State

      • Stresses, Shrinkage Voids

  • Solidification Of Molten Material Complete

Industrial Processes II


Welding basic process3

WELDING -- BASIC PROCESS

  • Weld Nugget, Components Cool to Room Temperature

  • Non-Corrosive/Protective Environment Withdrawn

  • Weld is Cleaned

  • Weld is Inspected/Tested/Approved

  • Paint or Other Coating Applied

  • Assembly is Used

    • Corrosion

    • Loading, Stress, Fatigue

Industrial Processes II


Welding metallurgy

WELDING METALLURGY

  • Melting/Fusion Process Similar to Casting and Heat Treating

  • Casting Review

    • Crystalline (Grain) Growth, Dendrites

    • Factors Affecting Grain Size, Shape

  • Heat Treatment Review

    • Annealing

    • Normalizing

    • Grain Growth

Industrial Processes II


Welding metallurgy1

WELDING METALLURGY

  • The Welded Joint (Heat Dissipation)

    [Kalpakjian, Figure 29.1, p. 909]

Q

Q

Industrial Processes II


Welding metallurgy2

WELDING METALLURGY

  • The Welded Joint (Heat Flow - Dendrites)

    [Kalpakjian, Figure 29.2, p. 910]

Industrial Processes II


Welding metallurgy3

WELDING METALLURGY

  • The Welded Joint

    [Kalpakjian, Figure 27.6, p. 863]

Industrial Processes II


Welding metallurgy4

WELDING METALLURGY

  • Solidification of the Weld Metal

    • Solidification Rate and Hardness

      Kalpakjian, Figure 29.3b, p. 910]

Industrial Processes II


Welding metallurgy5

WELDING METALLURGY

  • Phase Diagram

    Kalpakjian, Figure 29.4, p. 911]

Industrial Processes II


Welding metallurgy6

WELDING METALLURGY

  • Heat Affected Zone (HAZ)

    Niebel, et al, Figure 14.2, p. 629]

Industrial Processes II


Factors affecting weld quality

Joint Design

Process Used

Porosity

Slag Inclusions

Incomplete Fusion and Penetration

Weld Profile

Cracks

Tears

Surface Damage

Residual Stresses

Appearance

FACTORS AFFECTING WELD QUALITY

Industrial Processes II


Factors affecting weld quality1

FACTORS AFFECTING WELD QUALITY

  • Joint Design

    • Definition

      • Selection of the Relative Positioning of the Components to be Welded

      • Controls Area of Contact (Weld Strength - Anisotropic), Accessibility to Area to be Welded (Time, Skill Requirements, Welding Method)

    • Types

      • Single or Double

      • Square, ‘V’, Flare (Fillet), Bevel, ‘J’, ‘U’, ‘T’,

      • Corner, Edge, Butt, Lap (Overlap),

Industrial Processes II


Factors affecting weld quality2

FACTORS AFFECTING WELD QUALITY

  • Joint Types

    Kalpakjian, Figure V.4, p 857]

Industrial Processes II


Factors affecting weld quality3

FACTORS AFFECTING WELD QUALITY

  • Joint Types

    • Fillet (T)

    • Square (Butt)

    • Bevel

    • ‘V’

    • ‘J’

    • ‘U’

Industrial Processes II


Factors affecting weld quality4

FACTORS AFFECTING WELD QUALITY

  • Process Impact

    • Temperature Applied/Reached

    • Heat Flux (BTU/Min)

    • Size of HAZ

    • Protective Environment Provided

    • Amount of Material Supplied

    • Cost Of Equipment

    • Operator Skill (Cost)

    • Position (Vertical, Horizontal,Underwater, ...) Allowed

Industrial Processes II


Factors affecting weld quality5

FACTORS AFFECTING WELD QUALITY

  • Porosity/Voids

    • Definition

      • Discontinuities (Absences) in Weld Nugget

    • Causes

      • Trapped Gasses (Out-gassing from Metal or Flux, Smooth Spherical H2 , O2 , N)

      • Shrinkage Voids (Irregularly Shaped)

      • High Freeze Rate

      • Oil, Paint, Moisture, or Rust on Base Metal

      • Improper Arc Length or Current

      • Zinc Volatilization in Copper or Galvanized Base

Industrial Processes II


Factors affecting weld quality6

FACTORS AFFECTING WELD QUALITY

  • Porosity/Voids

    • Cures

      • Control Input Materials (Molten Materials)

      • Control Environment, Parameters

      • Control Process (Reduce Rate of Temperature Change, Control Solidification (from Interior))

      • Preheat, Pre-clean

      • ECuSi Electrodes (for Copper)

      • E6010 Electrodes (for Galvanized)

Industrial Processes II


Factors affecting weld quality7

FACTORS AFFECTING WELD QUALITY

  • Slag Inclusions

    • Definition

      • “Foreign” (Not the Base Material) Objects That are Trapped in the Weld Nugget

    • Causes

      • “Tramp” Materials in Rod, Components, Slag from Previous Pass

      • Corrosion or Combustion Products Trapped in Weld Nugget (Fast Freeze)

      • Residual Flux Materials

    • Cures

      • Compatibility of Rod, Component Materials

      • Control ‘Cleanliness’ of Workplace, Components

      • Control Cooling Rates

Industrial Processes II


Factors affecting weld quality8

FACTORS AFFECTING WELD QUALITY

  • Incomplete Fusion

    • Definition

      • Lack of Complete, Regular Crystalline Structure Throughout Proximate Base Material and Weld Nugget

    • Causes

      • Incomplete Melting (Mushy Zone or Insufficient Heat Flux)

      • Impurity or Void That Blocks Grain Growth

    • Cures

      • Increase Heat Flux, Temp. Reached, Preheat

      • Avoid Impurities and Voids

      • Improve Fit

Industrial Processes II


Factors affecting weld quality9

FACTORS AFFECTING WELD QUALITY

  • Incomplete Penetration

    • Definition

      • Weld Nugget Not ‘Deep’ Enough

    • Causes

      • Heat Dissipation Exceeds Heat Flux (Input)

    • Cures

      • Slow Welding Rate, Increase Heat Flux/Insulate

      • Preheat Components

      • Weld from Both Sides (Double vs. Single Joints)

Industrial Processes II


Factors affecting weld quality10

FACTORS AFFECTING WELD QUALITY

  • Weld Profile

    • Definition

      • Uniformity of Weld Cross-Section (Overlap, Under-Cut, Under-Fill)

    • Causes

      • Insufficient Filler Material

      • Melt Away Base Material (esp. Vertical)

      • Too Slow Freeze Rate (Vertical)

    • Cures

      • Proper Electrode/Position Combination

      • Proper Welding Technique, Parameters

Industrial Processes II


Factors affecting weld quality11

FACTORS AFFECTING WELD QUALITY

  • Electrode Notation/Parameters

    • E => Arc Welding (Ferrous)

    • 2-3 Digits => Tensile Strength (kpsi)

    • 1 Digit => Position (1=All, 2=Flat, ...)

    • -Suffix => Coating Composition and Current to be Used

    • e.g., E7011-C1

  • See Kalpakjian, Figure 27.4, p. 870

Industrial Processes II


Factors affecting weld quality12

FACTORS AFFECTING WELD QUALITY

  • Cracks (Weld Nugget)

    • Definition

      • Rupture or Tear (Physical Discontinuity) in Weld Nugget

    • Causes

      • Joint Too Rigid

      • Excessive Alloy Pickup from Base Metals

      • Defective Electrodes

      • Poor Fit (Variance in Nugget, Shrinkage)

      • Bead Too Small

      • High Sulfur in Base Metals

Industrial Processes II


Factors affecting weld quality13

FACTORS AFFECTING WELD QUALITY

  • Cracks (Weld Nugget)

    • Cures

      • Preheat Joints (Reduce Cooling Rate)

      • Use Correct Polarity, Welding Speed, Current

      • Change Electrode

      • Reduce Gap

      • Use Larger Electrode

      • Use Sulfur Fixing Elements (EXX18 Electrodes)

      • Fill in (Filler Metal) Shrinkage Prior to Withdrawal of Electrode (Similar to Concept of Riser in Casting)

Industrial Processes II


Factors affecting weld quality14

FACTORS AFFECTING WELD QUALITY

  • Cracks (Base Components)

    • Definition

      • Rupture or Tear (Physical Discontinuity) in Weld Nugget

    • Causes

      • H2 in Welding Atmosphere

      • High Strength - Low Ductility Material

      • Hot Tears (Copper Alloys)

      • Excessive Stress (Expansion/Warping)

      • High Hardenability

      • High Lead Content

Industrial Processes II


Factors affecting weld quality15

FACTORS AFFECTING WELD QUALITY

  • Cracks (Base Components)

    • Cures

      • Use Hydrogen Free Process (GMAW, GTAW, Submerged Arc)

      • Change Material or Anneal

      • Use Electrode with Similar Melting Point (Alloying)

      • Redesign Joint

      • Preheat, Slow Cooling Rate

      • Change to Lead Free Material

Industrial Processes II


Factors affecting weld quality16

FACTORS AFFECTING WELD QUALITY

  • Lamellar Tears

    • Definition

      • Tears or Cracking Along Grain Boundaries in Anisotropic Materials

    • Causes

      • Directional Cooling (Dendritic Structure)

      • Rolled Base Materials

    • Cures

      • Joint Redesign (Direction of Grain), Slower Cooling, Anneal or Stress Relief

      • Change Materials

Industrial Processes II


Factors affecting weld quality17

FACTORS AFFECTING WELD QUALITY

  • Surface Damage

    • Definition

      • Undesired Physical Changes to the Surfaces or the Base Materials

    • Causes

      • Spatter (Solidified Droplets), Pitting (Arc Strikes)

      • Excessive Heat (Discoloration)

    • Cures

      • Welding Technique

      • Surface Rehabilitation

Industrial Processes II


Factors affecting weld quality18

Factors Affecting Weld Quality

  • Residual Stresses

    • Definition

      • Unrelieved Forces Remaining in the Material Due to Limited Motion of Material (Constraints)

    • Causes

      • Differential Cross-Sections

      • Temperature (Size) Differentials Across Constrained Weldment When Weld Nugget Fuses

    • Cures

      • Redesign of Weldment, Fixturing

      • Preheating

Industrial Processes II


Factors affecting weld quality19

FACTORS AFFECTING WELD QUALITY

  • Weld Bead Appearance

    • Definition

      • Regularity/Consistency of Weld Bead

    • Causes

      • Varying (Filler) Material Deposition/Fusion Rates

      • Inconsistent Oscillation of Arc or Stick

    • Cures

      • Improved Welding Automation or Manual Technique

Industrial Processes II


Testing of welds

Destructive

Tension

Torsion

Bend

Peel

Fracture Toughness

Corrosion

Creep

Non-Destructive

Visual

Sonic (Brass Hammer)

Radiographic (X-Ray)

Magnetic Particle

Liquid Penetrant

Ultrasonic

TESTING OF WELDS

Industrial Processes II


Questions or clarifications

QUESTIONSOR CLARIFICATIONS ???

Reminder :

Industrial Processes II


  • Login