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

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.



GENERAL 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.

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

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.

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.

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%.

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.
• If possible for the firsts pass (butter pass) consider the E312 electrode except for water hardened steels.
• For water hardened steels use E11018 instead of E312 for butter pass.
• When using E312 use only one layer to avoid shrink cracks.
• If excessive hardness not required in weld use E312 then an E9018-6 or E11018-

   

• FOR LARGE COMPONENTS THAT REQUIRE BOTH STRENGTH AND HARDNESS
• First use E312 followed by E11018-G followed by the tool steel.
• Try to provide a minimum of 3 layers of tool steel weld to a minimum depth of 3mm.
• If the repairs are on annealed steels remember the electrode selected must respond to heat treatment after weld.
• The weld hardness will depend on the preheat/interpass temperatures plus weld procedures.
• The weld hardness will depend on the chemistry of the selected electrode along with the base metal dilution.
• The weld hardness will depend on the post heat treatment and cooling rate time.
• To join components, and prevent cracks preheat and deposit ductile electrodes.
• To prevent cracks, limit carbon pickup in first pass, (use low current narrow stringer beads) also if possible stress relieve.
• To minimize the potential for underbead cracks, preheat and limit heat input during the
  weld.
• To prevent underbead cracks provide uniform cooling, with immediate stress relief.
• Fast heating or concentrated heating can cause cracks.

  
  

  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) reheat at maximum pre heat recommendation.
  

TOOL STEELS, PRE HEAT BASICS

M-T-H-D2 Pre heat 900F (482C)

• All other tool steels preheat at 350F (176C)
• 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.

 

The "yield and tensile strength". The stress that can be applied to a base metal or weld without "permanent deformation" of the metal. The "tensile strength". The ultimate tensile strength, the maximum tensile strength that the metal or weld can with stand before "failure

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 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.

• Excess weld profiles.
• Welds with 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.

STRESS RELIEVING

• DECARBURIZATION = LOSS OF CARBON CAUSES SURFACE SOFTENING.
• Coating surface with Borax prevents decarburization.
  
  
• ANNEAL HEAT ABOVE CRITICAL TEMP THEN COOL 50F (10C) PER HR TO TEMPER.
  
  
• STRESS RELIEVE BELOW CRITICAL TEMP. TYPICAL 1100-1300F (700C) WITH SLOW COOL. Don't stress relieve a weld on hardened steel.
  
  
• 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.
• With hardened steel let steel cool to 150F (65c) then temper.
• For large repairs on hardened steels use the electrode temper requirements.
• Welding on hardened steels not tempered cracking will occur.

• Tool Steels Reference (A) Air Hardened.
• Tool Steels Reference(D) High Carbon Chrome Cold Worked.
• Tool Steels Reference (H) Chrome, Tungsten and Moly.
• Tool Steels Reference (L) Low Alloy High Wear Resistance / Toughness.
• Tool Steels Reference (M) Moly High Speed Steels
• Tool Steels Reference (O) Oil Hardened Cold Worked.
• Tool Steels Reference (P) Low Carbon Mold Steels.
• Tool Steels Reference (S) High Strength Medium Wear Resistance & Ductility.
• Tool Steels Reference (T) Tungsten High Speed Steels.
• Tool Steels Reference (W) Water Hardened Tool Steels.