Procedures For SMAW on Grey Cast Iron Flashcards

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1
Q

What should you use to preheat grey cast iron? What can be used to tell when you’ve reached your desired preheat?

A

A large propane burner-style torch, called a “tiger torch” take your time for an even preheat.

A hand held infrared temperature sensor, temperature crayons such as “tempilstik°” mark the workpiece with the crayon rated at the temperature you need and the mark will melt when it reaches the desired temperature.

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2
Q

Wha can be used for Insulating grey cast iron for post heating

A

Kaowool and vermiculite are the most effective but other commonly used are dry sand, lime, absorbent clay (floor dry) and fire brick

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3
Q

The best electrode to use for grey cast iron is?

A

Nickel alloys. A 36% nickel iron alloy contracts much less than cast iron and carbon steel electrodes. Which means theres less shrinkage so less of a chance of cracks developing

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4
Q

What is buttering?

A

In a large weld joint on grey cast iron you can reduce the cost by limiting the amount of nickel filler metal you use. “Buttering” means surfacing the weld joint with a nickel alloy, then completing the weld with a less-expensive filler metal. The layer of nickel filler metal is compatible with cast iron base metal and provides a base for a secondary filler metal. The secondary filler metal can be a lower nickel alloy or low-carbon steel electrode

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5
Q

A way to stop a crack you’re welding to spread

A

Drill a stop hole 1/8in in diameter just beyond where the crack ends an alternative is to run a small weld bead at 90° across the end of the crack

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6
Q

What temperature should you preheat small casting to? And large castings?

A

260C (500F)

520C (950F)

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7
Q

Procedures for cold welding

A

Use minimum current and small diameter electrodes
Deposit the weld bead in short lengths (about 50mm [2in.] or less). Separate the deposits by using a skip or back-step sequence. Peen immediately afterwards.

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8
Q

What must the thickness be a low carbon steel patch if used on grey cast iron?

A

60% of the thickness of the cast iron

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9
Q

Repair time for cold welding

A

25mm (1in.) Long weld beads at a time. Do not do the next one until you can put your hand on the first weld and feel no discomfort

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10
Q

Electrodes used for cast iron

A

RCI- welding rods intended for oxyacetylene welding

ECI- coated electrodes with a cast iron core

ESt- coated electrode with a stainless steel core. Deposit is hard and not machinable

ENI- coated electrode with a nickel alloy core. Deposit is machinable when using a 99% nickel electrode

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11
Q

What are the electrode sizes and current settings used

A

Most widely used 3.3mm (1/8in.), although most electrodes are available in sizes ranging from 2.5mm (3/32in.) to 3.2mm (1/8 in.)
Current settings are generally low, from 70 to 90 A. Both AC and DC can be used. AC is preferred, because it gives a smoother operation at lower current values and produces a less-penetrating

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