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Low Manganese Emission Shield Metal Arc Welding Electrodes

The role of Manganese in steels and steels welding

(Mn) is a very important and essential alloying element in steel. Together with carbon, manganese is responsible for the hardness and strength of steel. Besides this, manganese significantly improves the plasticity of steel and its toughness. It also works as deoxidizer and desulfurizer. There is no structure steel, which does not contain manganese.

Sources of Manganese

 

  • Core wire (0.4-0.5 wt-% of Mn)
  • Flux Coating (Mn contents depends on flux composition)
    • Ferromanganese powder
    • Electrolytic Mn powder

Health Effect of Manganese

High Mn exposure has been associated with central nervous system effects, referred as manganism.

Symptoms similar to Parkinson’s disease:

– Tremors

– Slowness of movement

– Muscle rigidity

– Poor balance

 

Male workers also have a higher risk of fertility problems.

Effect on nervous system is believed to be permanent.

If you would like to read more about health effect of manganese click here or here

 

Definitions

  • Threshold limit value-time weighted average:
    • TWA concentration for a conventional 8-hour workday and 40-hour workweek
    •  Believed that nearly all workers may be repeatedly exposed, day after day, for a working lifetime without adverse effect
  • TLV-Short term exposure limit (STEL):
    • 15-minute TWA exposure that should not be exceeded at any time during a workday, even if the 8-hour TWA is within the TLV-TWA

TLV – Threshold Limit Value

Manganese, Elemental and Inorganic Compounds

  • 2011: proposed, TLV-TWA, 0.02 mg/m3, as Mn,
    respirable particulate matter, and 0.1 mg/m3, as Mn, inhalable matter
  • 2013: 2011 proposed values adopted

Organizations

ACGIH – The American Conference of Governmental Industrial Hygienists

OSHA – Occupational Safety and Health Administration (USA regulatory body).

How do we measure exposure to manganese?

Standard method for sampling of air from breathing area of welder

Quality comparison for Manganese emission

WELDING CHAMBER

Almost all fume pass through the filter

 
Manganese content in regular electrodes

Type of coating Typical Fe-Mn content in flux (wt-%) Typical content in weld (wt-%)
Rutile E60139-100.4-0.5
Basic E70185-61.0-1.1

Manganese content in Zika’s Low Manganese electrodes

Type of coating Typical Fe-Mn content in flux (wt-%) Typical content in weld (wt-%)
Rutile E60135-60.24-0.28
Basic E701830.6-0.7

Preliminary results of Manganese emission – Rutile coating E6013

Electrode typeWelder’s exposure (mg/m^3)Welding chamber (mg/m^3)
Z-11 E60130.0070.54
E 6013 (Lincoln – USA)0.0080.52
 E6013 (Kiswel – USA)0.56
Z-11 LMn 0.0020.30

Preliminary results of Manganese emission –  Basic coating E7018

Electrode typeWelder’s exposure (mg/m^3)Welding chamber (mg/m^3)
Z-4 E7018 3.25 mm1.21
E7018-1 H4R Excalibur0.0131.22
Z7018 K3070.00960.78
Z 7018 LMn K336 0.0130.91

Here’s the Challenge

Because of the high manganese vapor pressure, the only way to reduce its emission during the welding process is to decrease the manganese content in consumable welding electrodes. Reducing the manganese content in the electrodes will reduce manganese content in weld metal. With less manganese in the weld metal, the main challenge is to meet the requirements of the mechanical properties of the weld metal.

Mechanical Properties E6013

 Yield p. (MPa)UTS (MPa)Elongation (%)Impact@0 CD (J)
AWS E6013 min. 330min. 430min. 17
EN IS0 E42 0min. 420500-640min. 2047 av.
Z11 – LMn4304802879 J

Mechanical Properties E7018 H4R

 Yield p. (MPa)UTS (MPa)Elongation (%)Impact@-30 CD (J)
AWS E7018 H4R min. 490min. 490min. 2227
EN IS0 E46 3min. 460530-680min. 2047
Z7018 – LMn52158027136 J

Welding for Well-Being

The Z-LMn rutile coated and basic coated electrodes have a unique flux composition which supplies weld metal with significantly lowered manganese content and therefore dramatically decreases the manganese emission in welding fume. The special weld metal composition of the Z-LMn provides the required mechanical properties and meets requirement of international standards. Pending patent No. 253605

Solid Welding Wire

Chemical Composition of Solid Welding Wire

Zika’s Brand NameASW A5.18CMnSiTiZrAl
ZR-6ER70S-60.06-0.151.40-1.850.8-1.15
ZR-2ER70S-20.070.9-1.40.4-0.70.05-0.150.02-0.120.05-0.15
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