Hardfacing Wear-resistant Centrifugal Fan

Overview

Hardfacing is the most established wear protection method: a high alloy wear resistant layer is deposited on the areas that wear, and hard phases resist abrasive cutting. It can be applied selectively and repaired locally, but heat input is high, so cracking and distortion must be controlled.

Zoned Hardfacing Scheme

Wear is not evenly distributed across an impeller; blade working faces and the inlet usually fail first, so hardfacing is applied by zone rather than as uniform thickening.

Location	Process	Typical figure
Blade working face	High alloy powder hardfacing	Deposit hardness typically HRC 55-62
Impeller side plates	Local hardfacing or wear plate	Applied according to the wear pattern
Volute casing	Replaceable wear liner	NM400 or NM500 grade plate
Inlet cone	Hardfacing or ceramic composite	Takes high velocity erosion
Shaft	Surface hardening or untreated	Preserves toughness and fitting accuracy

Hardfacing Procedure

Location	Process	Typical figure
Preheating	Preheat set by base and filler metal	Reduces cracking tendency
Layered deposition	Control of bead thickness and interpass temperature	Lowers residual stress
Post-weld cooling	Controlled slow cooling under insulation	Prevents the deposit cracking
Distortion control and re-balancing	Balance to G6.3 after hardfacing	Restores rotor balance
Post-weld inspection	Visual check plus hardness sampling	Confirms deposit quality

Applications

Applications include boiler induced draft, cement grinding, foundry sand handling, aggregate crushing and coal conveying.

Hardfacing is a wear part process, so the maintenance interval should be set by running hours and easily replaced components such as liners should be used.

A thicker deposit is not automatically better: excessive thickness raises the cracking risk, so depth is set from wear rate and inspection interval.

Acceptance and Verification

Standard	Title	Purpose
GB/T 984	Hardfacing electrodes	Selection of hardfacing consumables
GB/T 12444	Metallic materials - Wear test method - Block-on-ring sliding wear test	Wear test method
ASTM G65	Standard test method for measuring abrasion using the dry sand/rubber wheel apparatus	Relative abrasive wear resistance
GB/T 9239.1 / ISO 21940-11	Mechanical vibration - Balance quality requirements for rigid rotors	Impeller balancing grade
JB/T 10563	General purpose centrifugal fans - Technical specifications	General technical conditions and works acceptance

Please provide dust concentration, particle size and hardness, inlet velocity and air flow. Size and motor power are calculated for the actual duty.

FAQ

Must the rotor be re-balanced after hardfacing?

Yes. Hardfacing changes the blade mass distribution and the rotor must be re-balanced to GB/T 9239.1 (ISO 21940-11), normally to G6.3 or to G2.5 where speed is high or vibration sensitivity is critical.

Is a harder deposit always more wear resistant?

Only for abrasive wear. In high velocity erosion duty the toughness and bond quality of the deposit matter more, and simply raising hardness can introduce cracking.

How do I choose between hardfacing and ceramic composite?

Where particles are coarse and abrasive wear dominates, hardfacing is more economical and can be repaired on site. Where particles are fine, velocity is high and erosion dominates, ceramic composite or tungsten carbide coating is usually a better fit.

Related pages: Wear-resistant fan range  Wear-resistant centrifugal fan  Dust collection and wear protection