29204-15 Preheating and Postheating of Metals

Medium- or high-carbon steels are made hard and brittle by _____.

• postheating

• quenching

• preheating

• fluxing

Heavy plate and castings have a _____.

• high heat-absorption capacity

• low preheating temperature

• high quenching temperature

• low carbon content

When low-carbon steel with a carbon content of less than 0.30 percent is in freezing temperatures, it must be preheated to a temperature above _____.

• 40°F (4°C)

• 70°F (21°C)

• 100°F (38°C)

• 500°F (260°C)

To heat a metal with an open-top preheater, the object to be heated is mounted on a structure above which kind of burner?

• Gas

• Electric

• Combination oil and compressed air

• Combination gas and compressed air

In an induction heater, the magnetic field used to heat the metal is _____.

• constant

• confined

• low-level

• alternating

A noncontact instrument commonly used to measure temperature is a(n) _____.

• laser gun

• temperature stick

• infrared thermometer

• thermocouple device

Maintaining the temperature of the weld zone during welding is called _____.

• quenching

• conditioning

• preheat weld treatment

• interpass temperature control

What is the usual cooling rate per hour for stress relieving?

• 100°F to 400°F (38°C to 204°C)

• 250°F to 400°F (121°C to 204°C)

• 250°F to 500°F (121°C to 260°C)

• 300°F to 500°F (149°C to 260°C)

The process in which heat is applied to remove strains and reduce grain size is known as _____.

• annealing

• tempering

• normalizing

• stress relieving

Parts that have been hardened using the cold-forming process may look _____.

• brighter in appearance

• duller in appearance

• rusty orange

• rusty red