Choosing the Right Hardfacing Electrodes: A Guide

(1) Selection of Hardfacing Welding Rods

Unlike other welding rods, the selection of hardfacing welding rods does not require matching the composition or performance of the base metal to be hardfaced. Instead, it is based on the working conditions, processing requirements, and the type of metal to be hardfaced. When selecting hardfacing alloys, the following steps are generally followed:

1. Analyze the working conditions to determine potential types of damage and the requirements for the hardfacing metal.

2.List several available welding rods according to general principles.

3.Analyze the compatibility of the selected welding rods with the base metal, including the generation of thermal stress and susceptibility to cracking.

4.Conduct on-site trials of the hardfacing workpiece.

5.Finally, consider the service life and cost, and then select the hardfacing welding rod. Examples of hardfacing welding rod selection are listed in Table 2-70.

Table 2-70: Examples of Selected Hardfacing Welding Rods

operating conditionsTypical productsWelding Metal TypesOptional Hardfacing Welding Rods
ambient temperature metal-to-metal wearShafts and wheel wear surfacesLow-alloy Pearlitic SteelD102  D107  D112  D126  D127  D132
GearsAlloy Martensitic SteelD156  D172  D237
Punches, shearsAlloy Martensitic SteelD322  D327
moderate temperature metal-to-metal wearValve sealing surfacesHigh Chromium Stainless Steel, Chromium Manganese SteelD502  D507  D512  D516M D517  D507Mo  D577  D582
high temperature metal-to-metal wearHot forging diesHot Work Tool SteelD397
Hot extrusion dies, etc.D337
Valve sealing surfacesChromium-Nickel Austenitic Stainless SteelD547  D547Mo  D557
Cobalt-based AlloyD802   D812
Cutting toolsHigh-Speed SteelD307
metal-to-metal wear + abrasive wearRoad roller sprocketsLow-alloy Pearlitic SteelD102  D107  D112  D126  D127  D132
Blowdown valvesAlloy Martensitic SteelD207  D212  D217
ambient temperature high-stress abrasive wearBulldozer cutting edges, minecart, bucket teethAlloy Martensitic SteelD207  D212  D217  D227  D237
Alloy Cast IronD608  D618  D628  D642  D646  D667  D678  D687  D698
ambient temperature low-stress abrasive wearMud pumps, concrete mixer blades, screw conveyor, water turbine bladesAlloy Martensitic SteelD207  D212  D217  D227  D237
Alloy Cast IronD608  D618  D628  D632  D638  D642  D646  D667  D678  D687  D698
Tungsten CarbideD707  D717
Oil well drill bits, drill pipe jointsTungsten CarbideD707  D717
high temperature abrasive wearHigh-temperature ladles, coke pusherAlloy Cast IronD642  D646  D667  D656
abrasive and impact wearJaw crusher teeth, excavator bucket teethAlloy Martensitic SteelD207  D212  D217  D237
High Manganese SteelD256  D266
ambient temperature impact wearRailway turnouts, track shoesHigh Manganese SteelD256  D266
high temperature impact wearHot shears, hot sawsChromium Manganese Austenitic Stainless SteelD276  D277
moderate temperature corrosion resistanceBoilers, pressure vesselsChromium-Nickel Austenitic Stainless SteelA042
High-temperature Corrosion ResistanceInternal Combustion Engine Exhaust ValvesCobalt-Based AlloyD802  D812  D822  D842
High-temperature Erosive WearHydraulic Turbine BladesChromium-Manganese Austenitic Stainless SteelD276  D277
High-temperature Wear and Corrosion ResistanceBlast Furnace BellowsAlloy Cast IronD642  D646

(2) Precautions for the Use of Hardfacing Welding Rods

The key to wear-resistant hardfacing is to achieve sufficient hardness and minimize cracking. To achieve this, the following construction measures should be taken:

Cleaning of the Base Metal

Remove rust, oil, and original cracks from the base metal and repair areas.

Preheating and Interpass Temperature

To minimize cracking, strict control of preheating and interpass temperatures is necessary. The relationship between the steel’s carbon equivalent and preheating temperature is listed in Table 2-71. As shown in the table, with an increase in carbon equivalent, the preheating temperature also increases.

Table 2-71: Relationship between Steel Grade Carbon Equivalent and Preheat Temperature

Steel TypesCarbon EquivalentPreheat and Interpass Temperature/°C
Carbon Steel and Low Alloy Steel≤0.3≤100
High Manganese SteelNo preheat, water cooling between weld passes
Chromium-Nickel Austenitic Stainless SteelNo preheat, interpass temperature ≤150
High Alloy Steel≥400
①Carbon Equivalent = C + Mn/6 + Si/24 + Cr/15 + Mo/4 + Ni/15.

Post-weld Heat Treatment

Immediately after welding, the workpiece should be kept at 300~350°C for 10~30 minutes, which is very effective in preventing cold cracks.

Reduce Dilution Ratio

By using multi-layer and multi-pass welding, controlling the welding current, and reducing the depth of fusion, the amount of base metal melting can be decreased.

Cladding Isolation Layer for Build-up Welding

When performing wear-resistant build-up welding on high hardenability low-alloy steel or depositing high-hardness surfacing metal on carbon steel, the cladding isolation layer method should be adopted to prevent cracks.

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