ERCoCr-E Cobalt-Based Hardfacing Bare Rod / Welding Wire (Co-Cr-Mo Alloy)

Short Description:

ERCoCr-E (commonly known as Cobalt Alloy 21 / Stellite 21 equivalent) is a low-carbon, solid-solution-strengthened cobalt-chromium-molybdenum alloy. Unlike tungsten-bearing cobalt alloys (such as ERCoCr-A, B, and C), ERCoCr-E relies on molybdenum for matrix strengthening and features lower carbon content, resulting in significantly higher ductility, impact resistance, and thermal shock resistance. It possesses a unique work-hardening characteristic, where the deposit surface hardens under repeated impact or metal-to-metal contact, combining a tough underlying matrix with an abrasion-resistant wear face.

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1. Description & Applications

Key Applications:

High-temperature/high-pressure valve seats, discs, and gate valves
Hot forming dies, forging tools, and shearing blades exposed to thermal fatigue
Steam turbine components, pump shafts, and fluid-handling equipment
Metal-to-metal wear applications subject to severe mechanical or thermal shock

2. Nominal Chemical Composition (wt%)

Element	C	Cr	Mo	Ni	Fe	Si	Mn	Co
Min (%)	0.20	26.00	5.00	2.00	—	—	—	Bal.
Max (%)	0.35	30.00	6.00	3.00	2.00	1.50	1.00	Balance

3. Mechanical & Deposit Properties (As-Welded)

Hardness (As-Welded): 27 – 40 HRC (lower initial hardness for maximum toughness)
Work-Hardened Hardness: Up to 48 HRC under dynamic metal-to-metal impact and friction
Impact & Thermal Shock Resistance: Excellent; superior crack resistance compared to high-carbon cobalt alloys
Machinability: Readily machinable compared to other cobalt hardfacing grades due to its lower carbon content and solid-solution matrix.