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A comprehensive set of questions and answers related to asnt level ii welding exam. It covers various welding processes, including smaw, gmaw, fcaw, gtaw, and ofw, focusing on key aspects like current types, electrode types, welding techniques, and properties of stainless steels. Valuable for students and professionals preparing for asnt level ii welding certification.
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Correct Answer: Stick welding; Shield metal arc welding GMAW Correct Answer: MIG; gas metal arc welding FCAW Correct Answer: flux cored arc welding GTAW Correct Answer: TIG; gas tungsten arc welding OFW Correct Answer: oxy fuel welding the three types of currents that can be used while welding
Correct Answer: Direct Current Electrode Negative; Direct Current Electrode Positive; Alternating Current Straight Polarity Correct Answer: DCEN; direct current electrode negative Reverse Polarity Correct Answer: Direct current electrode positive; DCEP Current type depends on ___ for MIG and TIG and ___ for SMAW Correct Answer: MIG and TIG depend on type of metal being welded; SMAW depends on what type of electrode you are using Most common SMAW electrode types used Correct Answer: E6010 and E What current type do E6010 and E7019 for SMAW use Correct Answer: DCEP What type of current is used for GMAW (MIG) of steel Correct Answer: DCEP What type current is used for GTAW when welding stainless steel and carbon steel
Correct Answer: Oxygen (will create porosity or voids) and Hydrogen (will make the metal brittle and cause Hydrogen cracking) How does the slag that is not burned into shield gas operate? Correct Answer: It melts into the weld puddle, rises to the surface, and hardens on top of the weld. It needs to be removed Which processes have slag? Correct Answer: SMAW, FCAW How does FCAW differ from GMAW? Correct Answer: They are the same process except FCAW uses a tubular wire filled with flux and requires no external shielding gas source Describe how GMAW works. Correct Answer: Semi-automatic process with two leads (gun and ground); when gun is squeezed electricity flows and filler wire is fed. What are the parts of a GMAW gun? Correct Answer: Handle, trigger, and nozzle What type of filler wire is fed in GMAW? Correct Answer: Solid wire type
What nobs can you control on GMAW Correct Answer: Voltage and Wire Feed speed What are the 3 main transfer types for MIG (how the metal gets from the filler metal to base metal) Correct Answer: Short-Circuit, Globular, and Spray Transfer Where does the shield metal gas come from in MIG? Correct Answer: From a separate tank that is sprayed out of the nozzle in the gun In GMAW, what shield gas is used for carbon steel? Correct Answer: 75Ar/25Co What happens when you add Helium or Hydrogen to the shield gas for MIG of carbon steel? Correct Answer: makes the arc hotter Why is Co2 included in MIG welding of carbon steel? Correct Answer: it stabilizes the arc What are examples of manual, semi automatic, and automatic GTAW (TIG) welding? Correct Answer: Manual= hand welding with torch
What is the set up for OFW Correct Answer: acetylene, oxygen (separate tanks), and a torch Describe the process of OFW Correct Answer: Acetylene and oxygen come from their separate tanks and blend in the mixing chamber of the torch and create a flame What is another function of OFW and describe the process Correct Answer: cutting; this requires a different torch with an extra handle for the cutting oxygen (higher pressure than flame oxygen) blow the melted metal away from material being cut How is filler wire labeled? Correct Answer: by what the metal is What is the breakdown of filler wire labels? In ER70S- 6 ER= ___ 70= ___S= ____6 = ___ if it was E70T-6 the T = ___ Correct Answer: ER= electrode rod; 70= tensile strength (ksi); S= solid rod; 6 = chemical composition if it was E70T-6 the T = tubular for flux core wire
What does the filler wire label tell us about stainless steels? Correct Answer: Type of stainless, Ex. ER316L or ER304L What does the L in stainless steel names mean? Correct Answer: Low-carbon What are the 400 series stainless steels? Correct Answer: duplex stainless; they have a higher iron content and are magnetic What elements give stainless steels their corrosion resistant properties? Correct Answer: Chromium and nickel that create an oxide layer on the surface of the stainless steel What molecule is formed on the outer layer of stainless steels? Correct Answer: chromium oxide from the air What element can ruin the protective layer on the outside of stainless steels? Why? Correct Answer: carbon because it binds with chromium to create chromium- carbides that are less resistant to chemical attack When chromium-carbides form on the outer layer of stainless steels what chemicals will cause the material to corrode? Correct Answer: chlorides and acids (think stress corrosion cracking)
Correct Answer: better resistance to stress-corrosion cracking, pitting, and crevice corrosion than austenitic, also ferro-magnetic, has a BCC structure; less resistant to corrosion what are martensitic stainless steels known for Correct Answer: higher levels of carbon with very high strength; BCC structure, quenched; used often when hardness is critical what are austenite stainless steels known for Correct Answer: FCC structure, their nonmagnetic, good toughness and ductility at elevated and low temps, they have the best general corrosion resistance of all SS, higher Ni content what two types of metallurgy do duplex stainless steels contain? Correct Answer: austenite and ferrite, have the best properties of each what type of gas sheilding should be used for high purity stainless steels Correct Answer: fluxes should not be used only inert gases what is sugaring Correct Answer: sugaring is a black oxidation with white crystals and is an extreme condition of oxidation/contamination
occurs mainly in austenitic (at 800-1500 F) and ferritic stainless steels when chromium carbides or nitrides precipitate at grain boundaries, the more carbon in the SS the bigger the issue Correct Answer: sensitization or inter granular corrosion what is the max amount of carbon in SS to be considered low-carbon (specifically designed to avoid sensitization) Correct Answer: 0.03%wt (compared to normal having 0.08%wt) what type of corrosion in SS occurs when a small area can collect a concentration of corroded environment Correct Answer: crevice corrosion what type of corrosion in SS occurs because of a local segregation of corrosion resistant elements in the material Correct Answer: pitting corrosion how are pitting and crevice corrosion mitigated? Correct Answer: the addition of molybdenum and nickel (ex. 316L is a modification to 304L but with 2-3% Mo added) Most SS have matching filler metals; find the pair 304L =
what type of cracks form in SS when there is a fast travel speed? Correct Answer: centerline cracks what type of cracks form in SS when the crater of the weld is not filled properly Correct Answer: crater cracks when do hot cracks form? Correct Answer: when the weld is still hot and before it has cooled to room temperature what causes hot cracks? Correct Answer: tensile stress crack susceptible microstructure (austenite), contaminants (especially sulfur, phosphorous, titanium, niobium) how to reduce hot cracking in SS Correct Answer: use stringer beads reduce travel speed use high-ferrite base metal and/or filler use materials with low contaminants fill all craters reduce tensile stress (change joint design) avoid long arc lengths (introduces more N2 which makes it more austenite)
what type of SSs does cold cracking occur in? Correct Answer: martensitic SS and some ferritic SS what causes Cold cracking in SS Correct Answer: tensile stress crack-susceptible microstructure (martensite) hydrogen What are the best ways to avoid cold cracking Correct Answer: preheating to slow down the cooling rate so less martensite forms post weld heat treat to temper the martensite to make it more ductile What is the roughness average for mechanically polished surfaces? Correct Answer: Below 30 Ra What is the unit of measure for surface roughness? Correct Answer: Roughness average (Ra) What organization determines CFOS? Correct Answer: CGA G-4.1 (Compressed Gas Association) How can you verify if the material is cleaned for oxygen service?
What gas are we protecting stainless steel from when welding? Correct Answer: oxygen What gases can be used on stainless steel while welding (except TIG) Correct Answer: Argon, nitrogen, helium TIG welding needs to be ___ for stainless steels, why? Correct Answer: Argon bc nitrogen is too unstable and will not create a good plasma flow of the arc to the metal. He or H2 can be mixed to create a hotter arc but is discouraged for thin wall tubing What is the main priority of argon when purging? Correct Answer: remove oxygen and impurities from weld area What is significant about orbital welding and purging with argon? Correct Answer: A slight pressure is required on the ID so the weld does not become concave. What measures concavity or convexity on a weld? Correct Answer: Magnahelic (it measure pressure flow) What is significant about filling a tube with argon when welding?
Correct Answer: Argon is heavier than air. Fill from the lowest point to avoid pockets of air being trapped. What are other terms for the weld inspector? Correct Answer: Owner's inspector or 3rd party inspector What are the two ways to certify a weld inspector? Correct Answer: With an AWS CWI (American Welding Society Certified Welding Inspector) or ASNT SNT-TC-1A VT Level II (American Society of Non-destructive testing) How long is the ASNT Level II good for? Correct Answer: 5 years within the same company What level must a Level I work under? Correct Answer: Level II or higher List the five basic joint types in welding. Correct Answer: Butt joint Tee Joint Lap joint Edge joint Corner joint
Correct Answer: weld being cooled too quickly and will occur as the weld is cooling longitudinal to the weld why do cold cracks form? Correct Answer: cold cracks are caused by a stress factor on the joint that could cause cracking days after the weld has cooled and can occur transversely or longitudinally on the weld What is undercut? Correct Answer: when the welder was melting the base metal and melted part of it away and did not fill it in completely with the weld puddle. Will always be on the base metal - due to poor welding techniques what is porosity? Correct Answer: a void in the weld metal itself, caused by inadequate shielding of the weld puddle. caused by incorrect gas mixture, lack of gas, or bad techniques what is underfill? Correct Answer: when the surface of the weld extends below the surface of the base metal. What causes underfill? Correct Answer: caused by inadequate filler material to fill the joint
incomplete fusion Correct Answer: where the metal does not fuse into the base metal or the previous weld bead what causes incomplete fusion Correct Answer: inadequate welding techniques or insufficient heat what is incomplete penetration? Correct Answer: at the root of the weld where the weld does not fully penetrate the base metal and leaves part of the joint un-melted what causes incomplete penetration? Correct Answer: inadequate weld techniques, the root opening being too close, the filler rod size selection, or insufficient heat input what type of welding will you see arc strikes commonly Correct Answer: SMAW and GTAW what are arc strikes? Correct Answer: when the electrode touched the base metal outside of the weld zone and leaves a little spot of metaled metal
