CWB Module 9 correctly answered graded A+ 2023/2024

CWB Module 9 Adjacent to the molten metal is a zone that reaches high temperatures, but does not melt? - correct answer Heat affected zone Heating, melting, and solidification (cooling) of metal leave us with two important aspects to consider: - correct answer Metallurgical transformations and stresses and strains may be induced causing distortion and possible cracking The rate at which a lamp converts electrical energy into heat and light is given by: - correct answer current times voltage The units of current times voltage is: - correct answer amps x volts = joules per second (or watts) The proportion of total heat energy that enters the plate is known as: - correct answer Efficiency Which welding process has the highest efficiency? - correct answer Submerged arc welding 90-99% Which welding process has the lowest efficiency? - correct answer Gas tungsten arc welding 20-50% The energy input is an important parameter that relates to the - correct answer size of weld, the width of the HAZ, and the cooling time In general the higher the energy input - correct answer the larger the weld, the wider the HAZ, and the slower the cooling rate The same energy input can be achived with various combination of - correct answer welding current and speed Increasing the current and speed in proportion keeps the energy input and fillet weld size constant but - correct answer increases the penetration The rate of cooling in a given material will depend on four major factors: - correct answer heat input to the weld, thermal conductivity of material, plate thickness, and temperature of the plates (preheat or interpass temperature) Increasing the heat will - correct answer reduce the cooling rate Doubling the heat input for thick plates will - correct answer halve the cooling rate For thin plate, doubling the heat input will - correct answer reduce the cooling rate four times Preheat will - correct answer reduce the cooling rate For steel regions exceeding 723C will - correct answer Partially transform to austenite on heating Hydrogen cracking is also known as - correct answer cold or delayed cracking If hydrogen cracking is to occur, it will do so within - correct answer 48 hrs Hydrogen cracking may occur in - correct answer the weld metal and the heat affected zone Major factors influencing hydrogen cracking are: - correct answer susceptibility of the weld metal or HAZ to hydrogen embrittlement, hydrogen content, stress and strain level at the point of crack initiation, and temperature below 150C Hydrogen comes from the breakdown of - correct answer water and organic material such as grease, rust or paint