Stellite 6B Cobalt-Based Alloy Forged Bar

Product Overview: Stellite 6B Cobalt-Based Alloy Forged Rods

Stellite 6B (UNS R30016) is the most widely used forged grade within the Stellite cobalt-based alloy family. It belongs to the cobalt-chromium-tungsten (Co-Cr-W) series of wear-resistant and corrosion-resistant high-temperature alloys. This alloy is based on cobalt (with a remainder of approximately 58% to 62%), and through the addition of high chromium, tungsten, and carbon, it forms a dual-phase composite structure of “cobalt-based solid solution + dispersed hard carbides”.

Stellite 6B is a “all-round” engineering material specifically designed for extreme conditions involving extreme wear, high temperatures, and corrosion. Unlike the ordinary Stellite 6 (in the cast state), 6B refers to the deformed (wrought) state product obtained through hot forging/rolling processing. Through the hot processing, the coarse primary carbide network structure is broken down, significantly improving its toughness, plasticity, and impact resistance compared to the cast state of similar alloys.

Technical Specifications for Stellite 6B Cobalt-Based Alloy Forged Bars

Common Grades and Standards

Chemical Composition and Mechanical Properties of Stellite 6B Cobalt-Based Alloy Forged Bars

Chemical Composition

Stellite 6B is a cobalt (Co)-based alloy; the key alloying elements and their functions are as follows:

Mechanical Properties (Forged, Rolled, and Annealed Condition)

Although Stellite 6B entails a higher initial procurement cost, it offers exceptional overall economic value when viewed from a full life-cycle perspective:

Typical Cost Comparison

Summary of Life-Cycle Cost Advantages

• Significantly extended equipment lifespan: Under cavitation and erosion conditions, the service life is more than five times that of standard stainless steel.
• Reduced downtime losses: Maintenance intervals extend from months to years, significantly reducing unplanned downtime.
• Lower lubrication costs: Low friction coefficient enables lubrication-free operation.
• Reduced spare parts inventory: Extended component lifespan leads to a substantial drop in the demand for spare parts.
• Lower overall costs: A chemical plant achieved a 40% reduction in total costs after adopting Stellite 6B for centrifugal pump seal rings.

Stellite 6B Cobalt-Based Alloy Forged Rods: Applicable Conditions and Industries

Key Applicable Conditions

High-temperature wear: Metal-to-metal, abrasive, and adhesive wear in environments ranging from 500°C to 800°C

Corrosive media: Oxidizing acids, wet hydrogen sulfide, high-temperature sulfur-bearing atmospheres, seawater, etc.

Cavitation/Erosion: Cavitation corrosion caused by high-speed fluid impact

Unlubricated sliding: Metal-on-metal friction without lubrication

Thermal shock/Thermal fatigue: Conditions involving repeated heating and cooling cycles

Manufacturing Process and Machining Techniques for Stellite 6B Cobalt-Based Alloy Forged Bars

Typical Manufacturing Process

Smelting → Forging/Hot Rolling → Heat Treatment (Solution/Annealing) → Non-destructive Testing → Machining/Finishing → Factory Inspection

Key Process Nodes:

• Vacuum Induction Melting (VIM): Ensures high alloy purity and reduces impurities
• Secondary Refining (VAR/ESR): Further reduces gas and inclusion content
• High-Temperature Forging/Hot Rolling: Breaks up the coarse carbide network in the cast state, forming a uniform and refined recrystallized structure
• Solution Heat Treatment: Heating to 1232°C±14°C, holding for ≥15 minutes, air cooling

Dimensions and Supply Forms

Regular Stock Specifications:

• Forged Bars (Round Bars): Φ10mm ~ Φ300mm, fixed length or non-fixed length
• Plates/Thick Plates: Thickness ≥1mm, width… ≤1000mm, length customizable
• Forgings: Customized according to drawings

Delivery Condition:

Annealed (M): Default condition, optimal plasticity, easy for bending, welding, and other subsequent processing

Forged (R)

Solution-treated

Surface Grade:

• Pickled and passivated surface (removing oxide scale)
• Machine-finished bright surface (turning/grinding)
• Black skin state (original forged surface)
• Customization Capabilities:
• Single-piece blanking
• Waterjet cutting
• Beveling
• Outsourced finishing
• Small batch samples available

Quality Assurance and Company Advantages

Factory Inspection Items

The following certifications are available for Stellite 6B products:

• AMS 5894 Material Test Report
• Chemical Composition Spectroscopic Analysis Report
• Mechanical Properties Test Report
• Ultrasonic Testing Report

Company Strengths:

• End-to-End Process Control

Full traceability from smelting to flaw detection

Chemical composition and mechanical property data archived for every batch

• Flexible Customization

Small-batch sample shipments supported

Customization of non-standard forgings, rings, and tubular products based on drawings

Value-added services including precision cutting, waterjet cutting, and edge beveling

• Quality Assurance

Strict adherence to international standards such as AMS 5894 and ASTM

Third-party testing and certification available

Fine grain size requirements for forgings (ASTM Grade 5 or finer) to ensure ultrasonic penetration and isotropy

• Professional Service

Expert technical team providing material selection consultation

Rapid Response

Comprehensive after-sales technical support

FAQ

Q1: What are the differences between Stellite 6B and Stellite 6?

Stellite 6B usually refers to the deformed product after forging processing, while Stellite 6 generally refers to the cast state product. The chemical compositions of the two are similar, but 6B has a more uniform distribution of carbides after forging, and its impact toughness is about 4 times that of the cast state (typically lower than 5% for the cast state), with an elongation rate of up to 8%–15% (which is usually lower than 5% for the cast state). It is more suitable for manufacturing independent bearing wear-resistant parts.

Q2: What is the maximum operating temperature of Stellite 6B?

Stellite 6B can maintain high red hardness and strength even below 800°C. Its hardness can still remain above HRC 30 at 700°C. The key feature of its red hardness is that it retains high hardness at high temperatures and recovers to its original level after cooling.

Q3: Can Stellite 6B be welded?

1. Stellite 6B has excellent welding properties and can be welded onto the substrate surface using tungsten inert gas welding (TIG), oxy-acetylene welding or plasma arc welding. When used as a welding wire, it complies with the AMS 5798 standard. It is recommended to preheat to 200–400°C before welding, control the interlayer temperature, and cool slowly after welding to prevent cracking.

Q4: How difficult is the processing of Stellite 6B?

Stellite 6B has a relatively high hardness (HRC 33–43) and is a difficult-to-machine material. During the machining process, carbide or ceramic tools need to be used, with a lower cutting speed, a larger feed rate, and maintaining system rigidity. Grinding is the main finishing method for it, and it is recommended that professional manufacturers provide the processing services.

Q5: Is Stellite 6B restricted in nuclear power plants?

The cobalt element will generate the radioactive isotope Co-60 under irradiation conditions. Therefore, its application in the irradiation areas of nuclear power plants is strictly restricted. However, it can still be widely used in non-irradiated areas (such as wear-resistant components like valve internals).

Q6: How is the corrosion resistance of Stellite 6B?

Stellite 6B exhibits excellent corrosion resistance to a variety of corrosive media, including oxidizing acids (such as nitric acid), moist hydrogen sulfide, high-temperature sulfur-containing atmospheres, seawater, etc. It has a relatively high chromium content (approximately 30%), which can form a dense Cr₂O₃ protective film on the surface, providing excellent corrosion resistance protection in oxidizing media.

Q7: What is the minimum order quantity for Stellite 6B?

Normally, the minimum order quantity is ≥ 2kg. Small sample orders are also supported. The exact minimum order quantity depends on the specific specification.

Q8: What is the normal delivery status of the Stellite 6B forged bar?

The default delivery condition is annealed state (M), which offers the best plasticity and is suitable for subsequent processing such as bending and welding. Alternatively, forged state (R) or solutionized state can be provided according to customer requirements.