IIW IWI-B flashcards
IIW IWI-B · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Heat input formula
- Heat input in kJ/mm equals voltage times current times 60, divided by 1000 times travel speed in mm/min. It controls cooling rate and HAZ properties.
- Spray transfer condition
- Metal transfers as fine droplets above a transition current in argon-rich shielding. It gives deep penetration and smooth beads but is limited to flat and horizontal positions.
- AC for aluminium GTAW
- Alternating current alternates cleaning and penetration half-cycles. The positive half breaks the tenacious aluminium oxide, while the negative half limits tungsten overheating and provides penetration.
- Submerged arc welding limit
- Granular flux buries the arc, giving high deposition and no visible radiation. The process is restricted to flat and horizontal positions and to mechanised or automatic operation.
- Electrode force in spot welding
- Force holds the sheets together and forges the nugget during cooling. Insufficient force causes expulsion and porosity; excessive force reduces contact resistance and nugget size.
- Carbon equivalent formula
- IIW carbon equivalent equals C plus Mn/6 plus (Cr+Mo+V)/5 plus (Cu+Ni)/15. Values above about 0.40 percent indicate higher hardenability and cold-cracking risk.
- Hydrogen cracking triad
- Cold cracking needs a susceptible microstructure, diffusible hydrogen, and tensile restraint stress simultaneously. Removing any one condition prevents cracking.
- t8/5 cooling time
- The time to cool from 800 to 500 degrees Celsius. Higher heat input and higher preheat lengthen it, producing softer HAZ and lower cracking risk but reduced strength.
- Ferrite number in stainless
- Austenitic stainless weld metal with ferrite number 3 to 10 resists solidification cracking and stress corrosion, while avoiding excessive sigma formation at high temperature.
- Sensitisation temperature range
- Chromium carbides precipitate at grain boundaries between about 450 and 850 degrees Celsius. Chromium depletion lowers corrosion resistance; low-carbon or stabilised grades resist this.
- Aluminium 6082 versus 5083
- 6082 is heat-treatable and softens in the HAZ by overageing. 5083 is non-heat-treatable and work-hardened, so it anneals in the HAZ and loses strength there.
- Austenite to ferrite hydrogen drop
- Hydrogen solubility falls sharply when austenite transforms to ferrite. Rejected hydrogen concentrates in residual liquid and promotes porosity and cold cracking.
- Fillet weld throat formula
- For an equal-leg 90 degree fillet, throat thickness equals 0.7 times the leg length. Design calculations use throat area, not leg length.
- Weld symbol sides
- On a reference line with an arrow, a symbol above the line denotes the arrow side and below denotes the other side. The tail carries process or specification notes.
- Fatigue improvement methods
- Toe grinding, TIG dressing, and peening improve fatigue life by removing toe intrusions and introducing compressive residual stress at the weld toe.
- Distortion control methods
- Balanced welding about the neutral axis, back-step sequence, presetting, and reduced heat input limit angular and longitudinal shrinkage in fabricated assemblies.
- Partial penetration throat
- Effective throat for a partial penetration groove equals the specified groove depth, adjusted for root gap. Full penetration equals the plate thickness.
- Visual inspection lighting
- At least 500 lux is required at the inspection surface, with 1000 lux recommended for close inspection of critical welds and small surface defects.
- Magnetic particle limitation
- Magnetic particle testing detects surface and near-surface defects only in ferromagnetic materials. It cannot inspect austenitic stainless steel or find deep internal defects.
- Radiography versus ultrasonics
- Radiography detects volumetric defects such as porosity and slag. Ultrasonics detects planar defects such as lack of fusion and cracks, which radiography may miss when oriented unfavourably.
- Essential variables in a WPS
- Variables whose change requires requalification: process, base metal group, thickness range, filler classification, preheat, interpass temperature, and heat input range.
- WPS qualification sequence
- A preliminary WPS is drafted, a WPQR is produced by testing a test piece, then the WPS is issued. Welder qualification is a separate activity testing the operator.
- Undercut acceptance
- Undercut reduces throat thickness. Limits are usually a maximum depth, commonly 0.5 mm, combined with a maximum length relative to the weld length.
- ISO 3834 parts
- Part 2 comprehensive, Part 3 standard, and Part 4 elementary quality requirements for fusion welding. Selection depends on product criticality and contract requirements.
- ISO 9606 scope
- It covers qualification testing of welders for fusion welding. The test confirms the welder's ability, with essential variables defining the validity range of the qualification.
- NDT personnel certification
- ISO 9712 defines levels 1, 2, and 3. Level 2 may perform and interpret tests, while level 3 may approve procedures and supervise the NDT system.
- Execution classes EN 1090-2
- EXC1 to EXC4 define increasing requirements for steel structure execution, covering documentation, inspection extent, and welding quality demands.
- Arc eye cause
- Photokeratitis results from ultraviolet radiation from the arc. Prevention requires a filter shade matched to process and current, plus side shields on the helmet.
- Ozone in GTAW
- Ultraviolet radiation converts atmospheric oxygen to ozone, particularly in GTAW and plasma welding. Argon shielding does not prevent it, so ventilation is required.
- Confined space gas hazard
- Argon and carbon dioxide shielding gases displace oxygen in confined spaces. Entry requires gas testing and continuous monitoring before and during work.
- Fire watch duration
- A hot work permit requires removal of combustibles within about 10 metres. A fire watch is maintained for at least 30 minutes after completion, longer if specified.
- Visual inspection report content
- A report states project reference, WPS and welder ID, material and thickness, inspection stage, quantitative findings with location, cited acceptance criteria, and signed disposition.