CWB Module 9 exam questions with complete solutions

CWB Module 9 exam questions with complete solutions Heating, melting, and solidification (cooling) of metal leave us with two important aspects to consider: - 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: - Answer-current times voltage The units of current times voltage is: - Answer-amps x volts = joules per second (or watts) The proportion of total heat energy that enters the plate is known as: - Answer-Efficiency Which welding process has the highest efficiency? - Answer-Submerged arc welding 90-99% Which welding process has the lowest efficiency? - Answer-Gas tungsten arc welding 20-50% The energy input is an important parameter that relates to the - Answer-size of weld, the width of the HAZ, and the cooling time In general the higher the energy input - 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 - Answer-welding current and speed Increasing the current and speed in proportion keeps the energy input and fillet weld size constant but - Answer-increases the penetration The rate of cooling in a given material will depend on four major factors: - 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 - Answer-reduce the cooling rate Doubling the heat input for thick plates will - Answer-halve the cooling rate For thin plate, doubling the heat input will - Answer-reduce the cooling rate four times Preheat will - Answer-reduce the cooling rate For steel regions exceeding 723C will - Answer-Partially transform to austenite on heating