Below some Question and Answer about
Welding :
1) How do the welding requirements of AISC 360-05 generally differ from those in AWS D1.1?
The AISC Specification of chapter J invokes all the requirements of AWS D1.1. The noted in
the AISC Specification is excluded.
2) Which
AWS code is intended to apply to joints or members that are designed to resist yield level stresses or strains during design earthquakes.
AWS D1.8 is intended to apply to joints or members that are designed to resist yield level stresses or strains during design earthquakes
3) What two things are required in order to achieve a weld?
In order to achieve a weld, two pieces of metal have been heated and form by a hammer is required without any melting.
4) Molten metal, like the weld pool made during a welding process, has the ability to dissolve large quantities of gases such as nitrogen and oxygen. Why is this a problem and how is it avoided and controlled during welding operations?
The product of the nitrogen and oxygen in the molten metal will decrease the mechanical properties of the metal. To avoided and controlled during welding operations, all of the welding processes are required to accomplish the goals of atomic closeness and atomic cleanliness.
5) Shielding is typically accomplished by one of two means, or a combination of both. Name them and describe how and why they work. Fluxes melt to form slags, which may be used to coat the individual droplets of metal that leave the electrode. Additionally, once the slags contact the weld pool, they float to the surface and shield the pool as well. Slags act as a mechanical lid on the weld pool, keeping nitrogen and oxygen from contaminating the weld deposit. Additionally, such slags perform another important function: For out-of-position welding (vertical, overhead), the slag constitutes a mechanical support for the liquid weld metal, helping to shape the weld bead and hold it in place.
6) How does
brazing and soldering differ from arc welding?
Soldering filler metals melt at lower temperatures; brazing filler metals melt at a high temperatures, the temperature should be 450 °F or higher.
7) Describe the significance and meaning of a "prequalified" welding process.
The "prequalified" processes are those that may be used with a prequalified welding procedure specification.
The WPS matches all the requirements for prequalification; however it is not subject to qualification testing.
8) Which welding process is being used with an electrode classified as an E7018? Describe the meaning of each letter or number(s) in the electrode classification above. What is a commonly used slang name for this welding process?
"Code approved" is being used with an electrode classified as an E7018. E indicates an electrode. 70 specifies the minimum specified tensile strength in ksi. 1 indicates the position in which the electrode may be used. 8 designator to describe the coating type, welding current and CVN properties.
9) What part of the AWS D1.1 code requires that SMAW electrodes used to weld ASTM A992 steel be of "low hydrogen" type? What is the concern with using non-low hydrogen electrodes on this steel?
Table 3.1, which is in AWS D1.1 code, show the requirement that SMAW electrodes used to weld ASTM A 992 steel be of "low hydrogen" type. It has a greater ability to weld on contaminated materials and handle poor fit-up conditions.
10) What happens when a low hydrogen electrode package is opened and the electrodes are exposed to the air? What does the "R" indicate on SMAW electrodes bearing this designator? How should low hydrogen electrodes be stored overnight if their hermetically sealed packaging has been opened? Low hydrogen electrode will pick up the moisture from the atmosphere since the package is opened. "R"
indicates a low-hydrogen electrode that has been tested to determine the moisture content of the covering after exposure to a moist environment for 9 hours and has met the maximum level permitted in ANSI/ AWS A5.1. The Hydrogen electrodes can be stored in heated cabinet for overnight storage.
11) What are the two main limitations of the SMAW welding process?
The electrode is a variable resistor and a finite length.
12) What is FCAW and how do the electrodes used in FCAW differ from those used with the SMAW welding process?
FCAW is flux cored arc welding. FCAW have a finite length. It is because these wire electrodes are spooled onto packages that may consist of anywhere from 1 to 1000 lbs of materials. That the difference between SMAW and FCAW.
13) SMAW is a manual welding process, while most FCAW is done semi-automatically, and sometimes automatically. What is meant by manual, semi-automatic and automatic welding?
A manual welding process, while feeding the electrode into the puddle and propelling the electrode along the joint, the arc length must be maintained by the welder, which is the gap between the electrode and the workpiece. In automatic and semi-automatic welding, the operator does not need to maintain the arc length or feed the electrode into the puddle. The power supply maintains the arc length, and the wire feeder delivers the electrode to the arc.
In automatic welding, a mechanism propels the electrode along the joints.
14) Describe the meaning of each letter and number for an E70T-3 electrode. What kind of welding process is involved with this electrode? If a Charpy V-Notch toughness of 20 ft-lbs at -20 degrees Fahrenheit is required, is this electrode appropriate. Can this electrode be used to make a multiple pass fillet weld?
E indicates an electrode. 7 specifies the minimum specified tensile strength in ksi. 0 indicates the position in which the electrode may be used. T indicates a tubular electrode. 3 designator to describe the shielding type (e.g. Gas or self shielding), welding polarity, single versus multiple pass and CVB properties. "Code approved" welding process is involved with this electrode. It cannot specified if charpy V-Notch toughness of 20ft-lbs at -20 oF from Table 2-3. Therefore, it can't be used to make multiple pass fillet weld.
15) Name two distinct advantages of FCAW over SMAW.
The electrode is continuous, eliminating the built-in starts and stops that are inevitable with shielded metal arc welding. It increases amperages can be used with flux cored arc welding, with a corresponding increase in deposition rate and productivity.
16) What would a major limitation of the FCAW-G process be, with regard to field welding of a joint that is part of the seismic-force resisting system of a building? What concern with regard to the weld is being addressed by this limitation? Would you have the same concerns with FCAW-S?
The major limitation of the FCAW-G process would be the need for shielding gas. AWS D1.1 indicates the maximum wind velocity around an arc to 5 mph. A shelter or screen can be erected to limit such wind if necessary. It has the same concerns with FCAW-S.
17) What specific concerns might you have regarding the intermixing (for example between tack welds and welds) of FCAW-S and other welding processes? Does this same concern exist if both the welds and tack welds are made using only FCAW-S?
A very little shielding gas have been produced, however it relies on the addition of large amounts of deoxidizers and denitrifiers to react with oxygen and nitrogen. Aluminum is the primary element used for this purpose, titanium and zirconium may also be used as well. This concern exist if both the welds and tack welds are made using only FCAW-S.
18) Describe the SAW welding process. What positions can this process be used in?
An arc is shielded between one or more bare electrodes and the weld pools by a blanket of granular material called flux that is used to shield the molten metal.
19) What's the difference between active and neutral fluxes used in SAW?
The active fluxes contain deliberate additions of manganese and silicon and are primarily designed for single- or limited - pass welding. Neutral fluxes are designed primarily for multiple-pass weld and do not significantly change the manganese or silicon content of the weld metal.
20) What is the name of a welding process that is very similar to FCAW, but uses a solid or metal-cored electrode instead of a hollow, tubular electrode? What other major difference is there between these two electrodes, specifically with regard shielding of the molten pool? What are a few slang names commonly used for this process?
The gas metal arc welding (
GMAW) process is very similar to FCAW, but uses a solid or metal-cored electrode instead of a hollow, tubular electrode. GMAW power supplies may have additional controls for optimizing the output characteristics for certain modes of transfer.
21) Why is GMAW-S, often called "short-arc" welding, generally not suitable for making structural welds?
GMAW-S is a low-energy mode of transfer and welding on thin-gauge materials. It is the only suitable mode of transfer for all-position welding, unless pulsed spray transfer is used.
22) Welded studs are generally visually inspected. However, AWS D1.1 requires proof tests be made during production welding of studs to ensure proper procedures are being followed. Describe the process and frequency of this procedure. The stud need to be welded on a clean materials. When current is too low, or time is too short, the flash typically will not extend around the whole stud. When current is too high, or time is too long, the flash may
extend a long way beyond the ferrule, or may undercut the stud itself. The first two studs should be tested by mechanically bending them over to an approximate 30 degree angle from the original stud axis.
23) What is the formal name of the cutting process known as "burning" steel? Describe how it the process works.
Oxyfuel Gas cutting is the formal name of the cutting process known as "burning" steel. The thermal cutting process that relies on combustion of a fuel
