Hand welding practice problem_iii - Edwards @ Wiki

3 Structure / function / operation of welding machine

Question 3.1 Characteristic change of steel material with increase of added carbon

1. Easy quenching
2. Reduced elongation
3. Increase in tensile strength (increase in strength per unit volume)
4. Decrease in toughness

Question 3.2 Characteristics of steel material and weld characteristics
against increase in added carbon content

1. Tensile strength increases and weld characteristics decrease

Question 3.3 Properties of Steel for Increase in Carbon Content

1. Increase tensile strength
2. Hardness increases
3. Toughness decreases (viscosity)
4. Welding difficulties

Question 3.4 Weld characteristics in welded part against increase in added carbon

1. Welding construction becomes difficult and invites defects
2. Attract cracks as hardness of welds increases
3. Brittle part is generated due to heat effect of welded part
4. Attract cracks to welded parts as strength increases

Question 3.5 Characteristics of welded part against increase of added carbon

1. Easy quenching with improved bonding of inclusions
2. Weld part shrinks
3. Strength increases
4. Hardness of heat affected zone rises

Question 3.6 Characteristics of welding construction against increase in added carbon

1. Attract attention defects such as cracks to each property improvement such as strength

Question 3.7 Name of Steel-Based Metal Logarithm ?

1. Low Carbon Steel (Mild Steel): Carbon content is 0.03 to 0.3 [\%]
2. Medium carbon steel: carbon content of 0.3 to 0.6 [\%]
3. High carbon steel: Carbon content of 0.6 to 2.0 [\%]
4. Cast iron: Carbon content in the range from 2.0 to 4.5 [\%]

Question 3.8 Steel containing carbon content metal

1. Cast iron

Question 3.9 Additional elements / characteristics / name of steel materials

1. The properties of steel materials depend on carbon content
2. C Mn Si P S etc.

Question 3.10 Material of steel material

1. C and Si contain high content of cast iron
2. C content of low carbon steel is 0.3 [\%] or less
3. Hardness changes with C Mn Si
4. Steel for welding has lower content of C and S than ordinary mild steel
   1. P S enters from ore and coke during the refining process
   2. P S mixed amount descending order
      1. SS material: Steel Structure: general structural steel
      2. SM material: Steel Marine: steel for welding
      3. SN material: Steel New Structure: building steel

Question 3.11 Components of steel

1. Mn is the steel component
2. P S enters from ore and coke during the refining process
3. P S is the cause of the crack
4. Suppression of P and S of steel material to less than 0.04 [\%]

3.12 Formation of carbon steel Main important components

1. carbon

Question 3.13 Formation of carbon steel Main ingredients: the periodic table order

1. C
2. Si
3. Mn
4. P
5. S

Question 3.14 carbon equivalent

1. Comprehensive evaluation standard of welding construction characteristics
   Ceq = C_{r} + \frac{1}{6}Mn_{r} + \frac{1}{24}Si_{r}
   1. Good evaluation: Improve overall strength
   2. Low evaluation: Easy welding construction

Question 3.15 carbon equivalent

1. Evaluation criteria for welding characteristics of steel materials

Question 3.16 Elements related to carbon equivalent

1. C
2. Si
3. Mn

Question 3.17 Steel materials: Steel for welding construction

1. SM material: Steel Marin

Question 3.18 Measures against iron and steel weld failure

1. Select low-hydrogen type welding rod
   whose main component is formed by compound against steel which is easy to crack

Question 3.19 Performance change of welded part

1. Hardness rises against quenching

Question 3.20 Names of welded parts and adjacent parts

• Solidified structure: the entire fused portion of the base metal and the weld metal
  • Heat-affected zone: The portion heated to below the melting temperature
    of steel and whose material has changed
    • High temperature area: material crystal is large
    • Low temperature part: material crystal is small

Question 3.21 Hardening factor of heat affected zone

1. Hardening by hardening effect with rapid cooling

Question 3.22 Material change for steel cooling

1. Hardening of heat affected zone
2. Weakening in welds
3. Attract cracks along with rise in hardness at welds
4. The heat affected zone contracts

Question 3.23 Heat treatment

1. Preheating: heating to base metal before welding
   Prevent curing or cracking of welds
2. Postheating: heating to the weld after welding
   Prevent cracks by prolonging cooling time

Question 3.24 Welding target not requiring preheating

1. Welding of mild steel sheet

Question 3.25 Toughness of steel: Viscosity

1. Durability against destruction

Question 3.26 Tensile strength in SS 400 and SM 400
JIS: Japanese Industrial Standards

1. Unit: P = frac{F}{S} [N / mm^{2}]

Question 3.27 Function of coating agent on coated arc welding rod

1. Simple arc generation and maintenance
2. Shorter welding time and higher efficiency
3. Weld metal deoxidation and cleaning
4. Adjust melting point / viscosity / specific gravity of slag
   to ensure easy welding in each position

Question 3.28 Characteristics by coated arc welding rod

1. Iron powder oxidized covered arc welding rod: applicable to horizontal fillet weld because
   of good work characteristics
2. Low Hydrogen Coated Arc Welding Rod: Good Working Characteristics,
   Suppression of Crack Induced low Hydrogen Content
   1. Heated from 300 to 400 [^{circ}C] for 1 to 2 [h] before use and used within 3 to 4 [h]
   2. Heat from 100 to 150 [^{circ}C] and store
3. Illuminite type welding rod: Japan proprietary welding rod,
   applicable to all posture
4. High titanium oxide type coated arc welding rod generates stable arc
   and sputtering is small amount

Question 3.29 Low hydrogen hydrogen arc welding rod

1. Pre-service temperature: 300 to 350 [^ {circ} C (up to 400 [^ {circ} C])

Question 3.30 Handling of moisture absorbing coating welding rod

1. Peeling of the coating occurs and the arc is scattered
2. Disability independent of welding machine
3. Cause of blowhole
4. Cause of crack

Question 3.31 Low arc welding rod standard
        ex: Illuminite type / E 4319
        ex: Low hydrogen system / E 4316
       *_{1}*_{2} in E*_{1}*_{2} ** display indicates tensile strength
        ex: P = 43**: 430[N / mm^{2}] or more

Question 3.32 Coated arc welding for mild steel *_{1}*_{2} display in E ***_{1}*_{2}

1. Display on the type of coating agent

Question 3.33 Appropriate dressing for thin plate welding of coated arc welding

1. High titanium oxide type welding rod

Question 3.34 Characteristics of clothing arc welding rod

1. Illuminite type: Japan original standard, welding work property is good
2. High titanium oxide type: welding appearance is good, melting is small amount, arc is stable
3. Low hydrogen type: Good mechanical properties,
   slightly poor work properties, selected for joining with steel plate and constraint
4. Iron powder iron oxide system: Work and efficiency characteristics
   for horizontal fillet welding are good

Question 3.35 Selection of welding rod for weldable crack

1. Low hydrogen covered arc welding rod

Question 3.36 Clothes arc Welding rod symbol and covering classification

1. E4319: Illuminite type welding rod
2. E4303: Lime titania based welding rod
3. E4316: Low hydrogen type welding rod
4. E4313: Steel titanium oxide type welding rod

Question 3.37 Characteristics of low hydrogen type welding rod

1. Low content of hydrogen in the coating agent
2. Crack suppression against welding
3. Reduce the occurrence of cracks
4. Protection from oxidation by the inclusion of calcium carbonate

Question 3.38 Selection of coated arc welding rod

1. Appropriate selection for plate thickness, welding posture,
   type of structure and welding posture for welding
2. Weld tensile strength is properly selected by weld bar display E *_{1} *_{2} **
3. The performance of the weld is determined by the coating system
4. Coating promotes arc generation and maintenance / good mechanical properties

Question 3.39 Welding unnecessary heat after preheating

1. Mild steel

Question 3.40 Application of arc welding dressing

1. Arc control: ensuring stable generation and good quality of weld metal
2. Protection of welded parts: Suppression of oxidation and nitridation

Question 3.41 Effect of slag generation

1. Prevent oxidation and nitridation
2. Rapid cooingl of welded parts

Question 3.42 Welding section name

1. Weld metal
2. Heat affected zone
3. Base metal part

Question 3.43 Types and lines of welding rods in mild steel

1. E4313: High titanium oxide type welding rod: for thin plate
2. E4316: Low hydrogen type welding rod: suppress cracks
3. E4319: Illuminite type welding rod: Japan's own standard
4. E 4327: iron powder iron oxide type welding rod: for horizontal fillet meat

Question 3.44 Principle Performance change due to carbon equivalent
in added element to carbon content in steel component

1. Depending on the content rate of Mn and Si