Valve sealing surface cladding materials

1. Selection principles
(1) Medium characteristics
Corrosive media: Select materials with excellent corrosion resistance, such as stainless steel and nickel-based alloys.
High temperature media: Select high temperature resistant materials, such as cobalt-based alloys and nickel-based alloys.
Abrasive media: Select high hardness and wear-resistant materials, such as tungsten carbide-based cladding materials.
(2) Temperature and pressure
High temperature and high pressure conditions: Cobalt-based alloys (such as Stellite series) or nickel-based alloys are preferred because of their excellent high temperature strength and thermal fatigue resistance.
Medium and low temperature conditions: Iron-based alloys (such as martensitic stainless steel) or austenitic stainless steel can be selected, which have low cost and good processability.
(3) Sealing surface performance requirements
Wear resistance: Tungsten carbide-based cladding materials (such as WC-Co) have high hardness and excellent wear resistance.
Corrosion resistance: Nickel-based alloys (such as Inconel and Hastelloy) perform well in acidic and chloride environments.
Impact resistance: The cladding layer of iron-based alloy or low-alloy steel has good toughness and is suitable for impact load conditions.
(4) Process feasibility
Welding method: Select a suitable welding process (such as plasma arc welding, manual arc welding, laser cladding, etc.) according to the material properties.
Parent material matching: The thermal expansion coefficient and chemical composition of the cladding material and the parent material must match to avoid cracks or peeling.
(5) Economy
Cost-effectiveness: Under the premise of meeting performance requirements, materials with lower costs are preferred. For example, the cost of iron-based alloys is lower than that of cobalt-based alloys, but the performance may be slightly inferior.

2. Recommended material types
(1) Cobalt-based alloys
Features: high hardness at high temperature, excellent wear resistance, and good thermal fatigue resistance.
Applications: high temperature and high pressure valves (such as power station valves), strong wear conditions.
Typical grades: Stellite 6, Stellite 12.
(2) Nickel-based alloys
Features: strong corrosion resistance (especially acid and chloride resistance), good high temperature stability.
Applications: chemical valves, offshore engineering valves.
Typical grades: Inconel 625, Hastelloy C-276.
(3) Iron-based alloys
Features: low cost, good processability, moderate wear resistance.
Applications: valves for medium and low temperature conditions (such as water treatment valves).
Typical grades: AISI 410, AISI 420 (martensitic stainless steel).
(4) Tungsten carbide-based cladding materials
Features: extremely high hardness (HRC 60 or above), excellent wear resistance.
Applications: valves for strong wear conditions (such as mud valves).
Typical form: WC-Co alloy powder (plasma arc cladding).
(5) Austenitic stainless steel
Features: good corrosion resistance and high toughness.
Applications: valves for food and pharmaceutical industries.
Typical grades: AISI 304, AISI 316.

3. Typical application cases
(1) High temperature and high pressure steam valves
Clad material: cobalt-based alloy (Stellite 6).
Process: plasma arc cladding.
Advantages: high temperature resistance, thermal fatigue resistance, long life.
(2) Chemical corrosive medium valves
Welding material: nickel-based alloy (Hastelloy C-276).
Process: manual arc cladding.
Advantages: strong acid resistance and chloride corrosion resistance.
(3) Water treatment valves
Welding material: iron-based alloy (AISI 410).
Process: oxyacetylene flame cladding.
Advantages: low cost and wear resistance that meets requirements.
(4) Mud valves
Welding material: tungsten carbide-based alloy (WC-Co).
Process: plasma arc cladding.
Advantages: excellent wear resistance and resistance to mud and sand erosion.