CWB Module 22 question n answers graded A+ 2023/2024 passed

CWB Module 22Complete the following: a) Chromium stabilizes the _____ form of iron b) Nickel stabilizes the _____ form of iron - correct answer a) bcc b) fcc If a straight chromium steel of 18% Cr and < 0.1 % C is heated to 1000°C will it transform to austenite or remain as ferrite? - correct answer remain as ferrite What is the predominant structure of an 18% Cr, 8% Ni steel at room temperature? - correct answer austenite The chromium content of a stainless steel is 20%. Is it likely this is a martensitic grade? - correct answer No, Martensitic grade is 18% to 11.5% Cr A 14% Cr martensitic steel heated to 1000°C and air cooled produces a) ferrite b) aus1enite c) martensite - correct answer c) martensite Does an austenitic stainless steel have a greater or lesser work hardening rate than carbon steel? - correct answer greater A carbon steel component operates satisfactorily at 500°C under a stress of 50MPa. If 304 stainless were substituted, up to what level could the temperature be raised? - correct answer 600°C, 20% more then carbon The loss of corrosion resistance due to carbide formation and chromium depletion is known as: a) sigma formation b) sensitization c) stabilization - correct answer b) sensitization What maximum carbon level is usually specified to ensure freedom from sensitization during welding? a) 0.03% b) 0.003% C) 0.3% - correct answer a) 0.03% The presence of residual delta ferrite in the weld metal indicates that primary solidification was? a) ferrite b) austenite - correct answer a) ferrite A method of controlling weld metal fissuring is to always use a stabilized weld metal to ensure primary solidification is austenite: a) is to always use a stabilized weld metal b) to ensure primary solidification is austenite c) to ensure there is a small amount of residual delta ferrite in the weld metal - correct answer c) to ensure there is a small amount of residual delta ferrite in the weld metal True or false: "Welds in austenitic stainless steels are always preheated to prevent hydrogen induced cracking - correct answer False When a two layer overlay of stainless on carbon steel is made it is common practice to use E308 for the second layer and E _____for the first layer - correct answer (E309) on top of the carbon and then E308 Weld metal containing large amounts of ferrite and is exposed to high temperature service may: a) suffer embrittlement due to sigma formation b) have improved ductility due to ferri1e growth c) become air hardening - correct answer a) suffer embrittlement due to sigma formation Preheat is usually required when welding martensitic stainless steels: a) to prevent cracking b) to soften the HAZ c) to promote ferrite - correct answer a) to prevent cracking Why would 650°C be a better temperature to specify for a PWHT of a welded martensitic stainless steel than 550°C - correct answer To avoid temper embrittlement True or false: "Ferritic stainless steels are very tolerant of contamination during welding because of their very high ductility" - correct answer False True or false? "Conventional flame cutting with oxy-acetylene cannot be used on stainless steels" - correct answer True Which of the following actions might reduce the risk of carbon contamination in welding stainless steels? a} use aluminum oxide grinding wheels reserved for stainless steel b) use cellulosic type electrodes c} carefully clean off grease and dirt before welding d) use stainless steel cleaning brushes e} use C02 for back shielding the weld - correct answer a} use aluminum oxide grinding wheels reserved for stainless steel c} carefully clean off grease and dirt before welding d) use stainless steel cleaning brushes If a buttering technique is used to weld 304 stainless to mild steel what should be used for the butter layer? a) E48018 (mild steel) b) E308