Cutting Chapter 9 Flashcards
Used to maintain the temperature of the weld zone during the welding
Interpass Temperature Control
Quenching does not have much of an effect on low-carbon and mild steels because…
They dont contain much carbon
Quenching ——– and ——- carbon steels produces a hard and brittle crystalline structure.
It also reduces the metal’s toughness
Medium
High
T
Heavy plate and castings have a —– —- — —-that will cause the weld metal & adjacent base metal to quench unless they are adequately preheated
High Heat Absorbtion Capacity
Cause moisture in the weld zone to separate into hydrogen & oxygen
Welding Arc
The —– dissolves in the molten base metal, and the —— combines with other elements to form —–
Hydrogen
Oxygen
Slag
The hydrogen forms gas bubbles in the base metal along the weld boundary…
As the metal begins to cool.
Restricted joints, complex shapes, freezing temperatures and carbon content over .30 percent
Mild Carbon Steels
Low Carbon Steel (.1-.3 Percent) Shapes or Conditions
Freezing Temperatures
Low Carbon Steel (.1-.3 Percent) Preheat Temperature
Above 70’ F
During this, an alternating magnetic field is generated within the metal body being heated
Induction Heating
This thing is placed around the metal object, and a strong alternating current is passed through the coil
Magnetic Coil
Handheld device that measures temperature from the frequencies of the emitted electromagnetic waves of infrared or visible light.
Pyrometer
Noncontact instruments commonly used to measure temperature.
Optical Pyrometers
Devices that change form or color at specific temperatures or temperature ranges.
Temperature-sensitive indicators
Temperature-sensitive indicators include commercially made materials and devices such as 6 things
Crayon Sticks Liquids Chalks Powders Pellets Labels
When preheating is important, interpass temperature for multiple-pass welds is usually also important.
T
Often simply a continuation of preheating.
Heating equipment and techniques arent the same
Interpass Temperature
F
The most commonly used postheat treatment.
Stress Relieving
Stress Relieving is done below the lower transformation temperature, usually in the range of…. to …..
1,050 F to 1200 F
A process in which heat is applied to remove strain and reduce grain size.
Normalizing
Normalizing is done at temperatures and holding periods comparable to those used in….
Annealing
Tempering is aka
Drawing
Increases the toughness of quenched steel and helps avoid breakage and failure of heat-treated steel.
Tempering
Tempering is done at temperatures above the critical temperature.
F
Tempering is much lower than those used for ..3 things
Annealing
Normalizing
Stress Relieving
Tempering is commonly done to
tool steel
Parts that have been hardened using the cold forming process may look….
brighter in appearance
Electrical devices that often used to heat and relieve stress in metals
Ceramic Heating Elements
The individual ceramic components, or fingers, are threaded together as needed to cover the metal being heated.
The Heating Elements
Threaded through the individual ceramic fingers, and they heat the fingers when the power is applied.
Electrical Ceramic Fingers
Some codes cover…
stress relieving
Stress relieving codes specify the 3 things
Heating rate
Holding Time
Cooling Rate
