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Weld Heat Input worksheet

Grades 7–8

Solve each problem and show your work. Round answers to 2 decimal places where needed.

  1. Problem 1.
    • Arc voltage: 18 V
    • Welding current: 200 A
    • Travel speed: 20 in/min
    • Process (thermal efficiency k): Flux-cored, FCAW (k = 0.8)

    Find: Heat input

  2. Problem 2.
    • Arc voltage: 22 V
    • Welding current: 200 A
    • Travel speed: 18 in/min
    • Process (thermal efficiency k): Plasma arc, PAW (k = 0.6)

    Find: Heat input

  3. Problem 3.
    • Arc voltage: 32 V
    • Welding current: 180 A
    • Travel speed: 12 in/min
    • Process (thermal efficiency k): Stick, SMAW / MMA (k = 0.8)

    Find: Heat input

  4. Problem 4.
    • Arc voltage: 24 V
    • Welding current: 125 A
    • Travel speed: 8 in/min
    • Process (thermal efficiency k): None: arc energy only (k = 1)

    Find: Heat input

  5. Problem 5.
    • Arc voltage: 18 V
    • Welding current: 180 A
    • Travel speed: 18 in/min
    • Process (thermal efficiency k): MIG/MAG, GMAW (k = 0.8)

    Find: Heat input

  6. Problem 6.
    • Arc voltage: 20 V
    • Welding current: 100 A
    • Travel speed: 10 in/min
    • Process (thermal efficiency k): Stick, SMAW / MMA (k = 0.8)

    Find: Heat input

  7. Problem 7.
    • Arc voltage: 30 V
    • Welding current: 150 A
    • Travel speed: 8 in/min
    • Process (thermal efficiency k): Flux-cored, FCAW (k = 0.8)

    Find: Heat input

  8. Problem 8.
    • Arc voltage: 26 V
    • Welding current: 250 A
    • Travel speed: 8 in/min
    • Process (thermal efficiency k): Flux-cored, FCAW (k = 0.8)

    Find: Heat input

  9. Problem 9.
    • Arc voltage: 24 V
    • Welding current: 250 A
    • Travel speed: 20 in/min
    • Process (thermal efficiency k): TIG, GTAW (k = 0.6)

    Find: Heat input

  10. Problem 10.
    • Arc voltage: 30 V
    • Welding current: 125 A
    • Travel speed: 10 in/min
    • Process (thermal efficiency k): Submerged arc, SAW (k = 1.0)

    Find: Heat input

Answer key: Weld Heat Input worksheet

  1. 1. Heat input: 8.64 kJ/in

    1. Find the arc's power in watts: volts × amps

      18×200=3,600 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      18×200×601,000×20=10.8 kJ/in
    3. Multiply by the process factor k = 0.8, the share of heat that reaches the work, to get heat input

      0.8×10.8=8.64 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      8.6425.4=0.340157 kJ/mm
  2. 2. Heat input: 8.8 kJ/in

    1. Find the arc's power in watts: volts × amps

      22×200=4,400 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      22×200×601,000×18=14.666667 kJ/in
    3. Multiply by the process factor k = 0.6, the share of heat that reaches the work, to get heat input

      0.6×14.666667=8.8 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      8.825.4=0.346457 kJ/mm
  3. 3. Heat input: 23.04 kJ/in

    1. Find the arc's power in watts: volts × amps

      32×180=5,760 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      32×180×601,000×12=28.8 kJ/in
    3. Multiply by the process factor k = 0.8, the share of heat that reaches the work, to get heat input

      0.8×28.8=23.04 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      23.0425.4=0.907087 kJ/mm
  4. 4. Heat input: 22.5 kJ/in

    1. Find the arc's power in watts: volts × amps

      24×125=3,000 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      24×125×601,000×8=22.5 kJ/in
    3. Multiply by the process factor k = 1, the share of heat that reaches the work, to get heat input

      1×22.5=22.5 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      22.525.4=0.885827 kJ/mm
  5. 5. Heat input: 8.64 kJ/in

    1. Find the arc's power in watts: volts × amps

      18×180=3,240 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      18×180×601,000×18=10.8 kJ/in
    3. Multiply by the process factor k = 0.8, the share of heat that reaches the work, to get heat input

      0.8×10.8=8.64 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      8.6425.4=0.340157 kJ/mm
  6. 6. Heat input: 9.6 kJ/in

    1. Find the arc's power in watts: volts × amps

      20×100=2,000 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      20×100×601,000×10=12 kJ/in
    3. Multiply by the process factor k = 0.8, the share of heat that reaches the work, to get heat input

      0.8×12=9.6 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      9.625.4=0.377953 kJ/mm
  7. 7. Heat input: 27 kJ/in

    1. Find the arc's power in watts: volts × amps

      30×150=4,500 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      30×150×601,000×8=33.75 kJ/in
    3. Multiply by the process factor k = 0.8, the share of heat that reaches the work, to get heat input

      0.8×33.75=27 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      2725.4=1.062992 kJ/mm
  8. 8. Heat input: 39 kJ/in

    1. Find the arc's power in watts: volts × amps

      26×250=6,500 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      26×250×601,000×8=48.75 kJ/in
    3. Multiply by the process factor k = 0.8, the share of heat that reaches the work, to get heat input

      0.8×48.75=39 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      3925.4=1.535433 kJ/mm
  9. 9. Heat input: 10.8 kJ/in

    1. Find the arc's power in watts: volts × amps

      24×250=6,000 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      24×250×601,000×20=18 kJ/in
    3. Multiply by the process factor k = 0.6, the share of heat that reaches the work, to get heat input

      0.6×18=10.8 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      10.825.4=0.425197 kJ/mm
  10. 10. Heat input: 22.5 kJ/in

    1. Find the arc's power in watts: volts × amps

      30×125=3,750 W
    2. Find the arc energy per inch: power × 60 gives energy per minute, then divide by the inches welded per minute (and by 1,000 for kJ)

      30×125×601,000×10=22.5 kJ/in
    3. Multiply by the process factor k = 1, the share of heat that reaches the work, to get heat input

      1×22.5=22.5 kJ/in
    4. For kJ/mm, divide by 25.4, the millimeters in an inch

      22.525.4=0.885827 kJ/mm