CWB Module 22 Questions With 100% Correct Answers.

Complete the following: a) Chromium stabilizes the _____ form of iron b) Nickel stabilizes the _____ form of iron - 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? - remain as ferrite What is the predominant structure of an 18% Cr, 8% Ni steel at room temperature? - austenite The chromium content of a stainless steel is 20%. Is it likely this is a martensitic grade? - 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 - c) martensite Does an austenitic stainless steel have a greater or lesser work hardening rate than carbon steel? - 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? - 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 - b) sensitizationWhat maximum carbon level is usually specified to ensure freedom from sensitization during welding? a) 0.03% b) 0.003% C) 0.3% - a) 0.03% The presence of residual delta ferrite in the weld metal indicates that primary solidification was? a) ferrite b) austenite - 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 - 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 - 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 - (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 - a) suffer embrittlement due to sigma formationPreheat is usually required when welding martensitic stainless steels: a) to prevent cracking b) to soften the HAZ c) to promote ferrite - a) to prevent cracking