TIP TIG Welding is always better quality than TIG and 100 to 500% faster with superior quality than TIG - MIG - FCAW.

Written by Ed Craig
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ASTM Welding A403-A643 Carbon Low Alloy Steels.

Bar Plate and Pipe..

ALL ELECTRODE RECOMMENDATIONS MADE AT THIS SITE REQUIRE WELD QUALIFICATION BEFORE THE WELD CONSUMABLES ARE APPROVED.


Note: When you see high tensile weld electrodes required, this is usually an indication that pre heat interpass and post heat treatment is required for the welds

Fatigue:
The ability of a metal or weld to withstand repeated loads. Fatigue failures occur at stress levels less than the metal or weld yield strength. Some things that can influence fatigue failure:

• Excess weld profiles.
• Welds which cause undercut.
• FCAW or SMAW slag inclusions.
• Lack of weld penetration.
• Excess weld heat, typically from multi-pass welds without inter-pass temp controls.
• Items to a part that adds restraint while welding.
• Items added to a part that can concentrate stresses in a specific location.
• Incorrect selection of filler metal, weld too weak or weld too strong.
  

When welding low and medium carbon steels, the 70XX electrodes and E70S-3-6 MIG wires and E7XT-X flux cored electrodes can be used. When welding low alloy 1 1/4 Cr 1/2 Mo and 2 1/4 Cr 1 Mo with up to 0.05% max carbon, typically 8018-B2L / 9018-B3L (L = low carbon) can be used. When welding higher strength alloys or when tempering and quenching are required to attain the higher strengths the higher carbon 8018 B2 and 9018 B3 electrodes are utilized.

SMAW and GMAW Mechanical Strength
E6010 Minimum Yield 50,000 psi Minimum Tensile 62,000 psi.
E6011 Minimum Yield 50,000 psi Minimum Tensile 62,000 psi.
E7010 Minimum Yield 60,000 psi Minimum Tensile 72,000 psi.
E7018 Minimum Yield 60,000 psi Minimum Tensile 72,000 psi.

The commom MIG E70S-3-6 wires.
Minimum Yield 60,000 psi Minimum Tensile 72,000 psi.

Mechanical Strength of Gas Shielded Flux Cored Electrodes, reference ANS I /AWS A5.29 1198 Specification. Low Alloy Steel Electrodes for Flux Cored Arc Welding

What is Brittleness?
The ease at which the weld or metal will break or crack without appreciable deformation. When a metal gets harder it becomes more brittle. Preheat, inter-pass temp controls and post heat all are designed to reduce the potential for brittleness.

 

 

How do you measure Hardness?.
The hardness tester forces a small sphere (Brinell, HB), a diamond pyramid (Vickers, HV) or a cone (Rockwell C, HRC) into the surface of a metallic material. The indentation is then measured.

Welding alloy steels often may require unique weld or heat treat considerations. Compare the low alloy steels chemistry and mechanicals with a standard A36 steel. Remember this site is only a guide, weld responsibility starts with "you" First verify the weld consumable and then the material heat treat recommendations.

What is yield strength? The stress that can be applied to a base metal or weld without permanent deformation of the metal is the yield strength.

What is tensile strength? The ultimate tensile strength is the maximum strength that the metal or weld can withstand before failure occurs.

 

Metric Conversion 1000 psi = ksi x 6.894 = MPa

When mill scale is a problem, what MIG or flux cored weld parameter will the welder have to change and why? The solutions are in Ed's books.

 

STRESS RELIEVING (SR) BASIC GUIDELINES:

• STRESS RELIEF - CONTROLLED HEATING & COOLING TO REDUCE STRESS.
• STRESS RELIEF MACHINED PARTS FOR DIMENSIONAL STABILITY.
• STRESS RELIEF SLOW HEATING AND COOLING REQUIRED
• CONFIRM WITH CODE SPECIFICAIONS FOR STRESS RELIEF REQUIREMENTS.
  
  
  
  
  

 

 

E-Mail Feb 2007. Ed what affect does flame cutting API X-80 or 550 gr. pipe have on the weld HAZ?
Is 6010 a good root pass electrode for this material?

All X-80 materials are not created equal: They could be seamless quench and tempered, or DSAW TMCP plate. You can get some seamless that will have high alloy content that will produce a very hard HAZ, these alloys can be susceptable to hydrogen cracking. You need to consider minimum preheat and interpass temp controls and possibly avoid cellulosic electrodes such as 6010. The TMCP materials typically provide excellent results such as a soft HAZ from low minimum preheat.

What is lamellar tearing?

When welding, the weld shrinkage stresses impose tensile strains in the steel plate or on inclusions paralleled to the plate surface. The tensile strains can separate the inclusions causing cracks. Excessive strains can further elongate the cracks. Carbon, manganese and low alloy steels made at the mill with inadequate deoxidization are sensitive to lamellar tearing. The potential for lamellar tearing increases with the amount of inclusions in the plates being welded. Of special concern is when the inclusions are parallel to the plate surface. More data in ASTM A770 / A770M Standard Spec for through thickness tension testing of steel plates.

 

 

What is Ductility? The amount that a metal or weld will deform without breaking. Measured on welds by the % of elongation in a 2 inch 51 mm test piece. An E71T-1 flux cored electrode should result in a minimum of 20% elongation. An E70S--6 MIG weld should produce approx 22%.

 

What is Toughness?The ability of the metal or weld sample at a predetermined temperature to withstand a shock.The test for toughness measures the impact of a pendulum on a notched specimen. You may see that the required impact properties for the metal or weld are 20ft-lbf @ -20 F (27 j @ -29C)

If you are welding a carbon steel and you don't know what the composition is or what the weld consumable should be, try the following:

• If the metal is thicker than 1/4 (>6 mm,) preheat to 150F.
• Use either an E7018 stick electrode, an 0.035 or 0.045 E70S-3-6 MIG wire.
• For your all position welds an 0.045, E71T-1 electrode wire.
• For MIG welding use an argon 10 to 20% CO2 mix.
• For the flux cored use a mix with 20 to 25% CO2.
• Ensure with multi-pass welds you use inter-pass temp control.
• Ensure the inter-pass temp weld temperature does not exceed 300F.
• Use stringer passes.
• If possible do a mechanical / destructive test of the weld samples.
• If possible have the hardness and grain size checked after welding.
  
  
  
  

Provide the following info on why inter-pass temperature control is essential
for some multi-pass welds.

[1] Inter-pass temperature control can restrict the weld and base metal grain g____h

[2] Inter-pass temp control can limit the weld h___t minimize the H___Z and reduce the weld o_________on potential

 

Name two reasons why pre-heat is essential for some steels.


[1] Preheat can remove sources of h______ n

[2] Preheat can slow down the c______g rate.

The average person that comes to this site will this week spend $40 on booze, $60 in a restaurant, $15 on coffee, $30 for cigarettes, $40 on cable TV, $7 on videos, however most will have to think twice about purchasing a welding book or weld video, products that can influence their careers and future earning potential.

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