Chapter Six Quiz Flashcards
In some steels, a very slow cooling rate may produce a coarse grain structure in the heat affected zone. What may be the effects of such a structure?
Structures can have relatively low toughness.
The energy input is a very important parameter. To which significant parts of the weld operation and weld does it relate?
Size of weld, wide of HAZ, and cooling rate.
Lamellar tearing is an infrequent defect due to improvement in steel cleanliness, however it still occurs in steel. What is the most likely place for this to occur?
Most susceptible in Thick T butt joints and corner joints where strains are normal to plate surface.
In the heat affected zone, regions that are close to the fusion boundary can experience temperatures sufficiently high that growth of the austenite grains occurs. What governs this growth?
Extent to which they grow depends on the energy input.
One test to evaluate cracking is the Tekken test. In this test how do researchers promote cracking in the materials HAZ?
Sloping Y groove preparation.
Where high toughness is required in submerged arc welds, fluxes that provide a certain property must be selected. What is this property?
Basic fluxes that provide low oxygen.
Which of the following situations may assist in the initiation of hydrogen induced cold cracking in susceptible materials?
Joint misalignment or high and low at the root of the pipe.
In a susceptible steel, what steps can be taken to prevent the production of martensite in the weld zone?
Ensure the cooling rate is sufficiently slow.
Some electrode coatings are described as “basic” and these kinds of electrodes will:
Release C02 into arc atmosphere and thus, lower amount of hydrogen gas present.
What is the Carbon Equivalent (CE) of a steel?
Measurement of steels hardenability.
The cooling rate is very important in welding and the rate of cooling in a given material depends on a number of factors: which are?
Heat input, thermal conductivity of the material, material thickness, and temperature of the plates.
The dilution of a joint will vary according to the welding process, the welding procedure and the joint preparation. Of the following, which would be considered as having the greatest dilution potential?
An electroslag weld.
Structural steels may be split into zones that indicate the techniques that may be used to resist the onset of HICC. What is a Zone III steel?
Steel where hydrogen control must be used to prevent the onset of HICC.
The proportion of total heat energy that enters the plate is known as the efficiency and it varies with the welding process used. Which of the following arc welding processes is the least efficient?
GTAW.
What is dilution?
Change in chemical composition of weld metal due to admixture of filler metal and base metal.
Local stresses may assist the onset of cracking associated with hydrogen. Where can these local stresses be generated?
From restraint and stress risers.
There are techniques that can be used to control HICC from a welding procedural viewpoint. Which of the following can be one these approaches?
Controlling hardness of weld zone to a critical number such as 350 HV.
Hydrogen Induced Cold Cracking (HICC) has a peculiar property that is different from other cracking mechanisms. What is this property?
Cracking may be delayed.
The G-BOP test is a weldability test designed to study:
Weld metal cracking.
There are some peculiar features of the cracking mechanism known as hydrogen embrittlement. Which of these is one of the features?
Occurs below temperatures of 150C.
What can be said about the data derived from experimental cracking tests of weld zones?
Are mainly comparative and should not be used directly as they only stimulate lab conditions.
Which of the following can increase the probability of hydrogen-related cracking in the weld zone of a susceptible material?
Preheat below that given welding procedure which increase the cooling rate.
Creep strength in the wrought ferritic steels can be achieved by which of the following kind of metallurgical engineering?
By alloying elements that provide enhanced strength at high temperatures such as Cr and Mo.
What is a possible source of hydrogen that could be present in a weld zone?
Breakdown of water and organic material in weld area.
