(O) Oil Hardening Cold Work Steels

 

(O) Steels O1-2-6-7 ASTM A681 UNS T 31501-7
O Steels Hardness Range 57 - 64 rockwell
O Steels have less distortion and crack potential than (W) steels.
O Steels have low red hardness cold work applications.
O Steels machinability 70 to 90% of (W) steels.
O Steels weld pre-post heat interpass temp 350F (176C).
O - 1 - 2 After weld cool to 150F (65C) then temper 400F (200C)
O - 6 - 7 Weld pre heat 450F (230C) Temper 450F Several hours.
O Steels harden temperature 1450F - 1500F (790 - 815C)
O Steels Anneal temp 1425F (773C)
O Steels Tempering temp 350 - 500 F (175 - 260C_



Welding:
If hard surface not required consider E312 + E9018 / E11018
Use lowest amps, short arc length short bead, air cool




Consumables
Certanium - SMAW 213 TIG 13
Eutectic - SMAW 71-M TIG 70-A
UTP - SMAW / TIG OH1
Weldmold - SMAW 935 TIG 935 T
MG - SMAW 710
ALL State - OH




O1	UK B01 Germany 1.2510 Carbon max 1.0 Mn 1.4 Cr 0.6 W 0.6 V 0.3
02	UK B02 France 90 MV8 Germany 1.2842 Carbon max 0.95 Mn 1.8 Cr 0.35 Mo-Ni-V 0.3
O6	Carbon 1.55max Mn 1.1 Si 1.5 Cr - Mo-Ni 0.3

 

 

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.

 

Hardness:The resistance of the metal or the weld to penetration. Hardness is related to the strength of the metal. A good way to test the effectiveness of the weld procedure after the weld and heat treatment is complete, test the hardness of weld and the base metal surrounding the weld.

 

 

CONSIDERATIONS FOR WELDING TOOL STEELS:

• Ensure base metals are clean avoid tool marks.
  
  
• Remove all sharp edges and tight corners in weld areas

  Use Dye pen to check for surface cracks.

• Majority of tool steels will be weld repaired in the Hardened condition.

A hardness test will determine if steel is hard or annealed.

To weld massive tool parts with large amounts of weld "anneal first"

• Steels in the annealed condition metal can be removed with an oxy acet/fuel torch.
• Steels in the hardened condition use grinding/carbon arc rather than oxy fuel or plasma to remove metal.
  
  
• Discoloration glazing of steel while grinding indicates damage.
  
  
• Preheating before grinding or oxy cutting prevents damage
  
  
• ALL TOOL STEELS MUST BE PRE HEATED BEFORE WELDING.
  
  
• Pre heat prevents cracking, distortion stresses and shrinking.
  
  
• Annealed or hardened steels the steel must be pre heated.
  
  
• If base metal hardened yet not tempered anneal temper first.
  
  
• Preheat hardened steels don't exceed temper temperature.
  
  
• Hardened steels if temper unknown >25mm use 300 to 400F preheat.
  
  
• Annealed steels, preheat at maximum pre heat recommendation.

WELDING TOOL STEELS:

• With all tool steels the first weld consideration should be does the weld require the same hardness as the base.
• Is the metal to be welded in the annealed or hardened condition.
• Use lowest possible weld current, (smallest electrode diamaeter)
• No weaves use stringer beads.
• Peen each weld after completion,
• Ensure parts are clean.
• Avoid excess joint restraints.
  
  
  
  
  
• TOOL STEELS AND SMAW ELECTRODE DATA.
• SMAW Electrodes most versatile weld process for tool steels.
• Electrode 3/32 2.5mm amperage 50 to 80 amps DCSP
• Electrode 1/8 3.2.5mm amperage 70 to 115 amps DCSP
• Electrode 5/32 4mm amperage 100 to 150 amps DCSP
• Most tool and die SMAW electrodes use AC-DC Positive.
• Flux cored good for welds which benefit from high weld depositions.
• GTAW, TIG good for small precise welds.
• Don't use oxy fuel to weld.
• Ask. Is the weld for joining or does the weld require a specific mechanical property ( hardness or machinability)?
• Use smallest electrodes possible.
• Peen each weld bead.
• Avoid arc strikes.
• Consider run on plates.
• Avoid craters.
• Try to use stringers rather than weaves.
  
  
  
  
• TOOL STEELS, PRE HEAT BASICS
• Preheat "slowly" The higher the alloy content the slower the preheat.
• Preheat, the more complex the part shape the slower the preheat.
• Preheat. High alloy steels avoid oxy fuel use ovens or electric.
• Preheat. Use insulation around part to retain heat.
• Preheat. Maintain preheat during welds, don't exceed preheat temp.

 

 

• TOOL STEELS AND PRACTICES TO AVOID CRACKING.
• Annealed steels preheat, for the weld stress relieve, machine harden temper.
• Hardened steels, pre heat, weld temper then grind finish.

 

• DECARBURIZATION = LOSS OF CARBON CAUSES SURFACE SOFTENING.
• Coating surface with Borax prevents decarburization.
  
  
  
  TEMPERING FOLLOW AFTER QUENCHING TO REDUCE HARDENING STRESSES.
• High temper provides more toughness with less hardness.
• Tempering at low end provides max hardness (max wear) with less toughness.
• Tempering above Temper range reduces toughness.
• For large repairs on hardened steels use the electrode temper requirements.
• Welding on hardened steels not tempered cracking will occur.

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.

If steels are quenched and tempered to match properties electrode selection and
heat treatment recommendations critical.

 

HARDNESS CONVERSION FOR CARBON AND LOW ALLOY STEELS.
1000 psi = ksi x 6.894 = MPa

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