What is the impact of the pump body material of a multistage pump on the pump's performance?

Multi-stage pump body material selection directly affects the pump's pressure resistance, abrasion resistance, corrosion resistance, thermal conductivity and structural stability, which in turn has a key impact on the pump's performance (such as head, efficiency, life, reliability). The following analyses from the perspective of the material characteristics and performance correlation:
First, pressure resistance and strength: determine the upper limit of the pump's working pressure
1. The risk of insufficient material strength
Phenomenon: pump body deformation due to high pressure (such as bulging, cracks), resulting in media leakage or seal failure.
Typical case: cast iron (HT200) pump body for more than 1.6MPa pressure scenarios, may be in the flange connection leakage; and cast steel (ZG270-500) can withstand more than 3.0MPa pressure.
Impact on performance: Insufficient pressure resistance will limit the head of the pump (head ≈ pressure × 10.2), for example, a pump is designed for a head of 200m (corresponding to a pressure of 2.0MPa), if the pump body material pressure resistance is only 1.6MPa, it may be damaged due to overpressure during actual operation.
Wear resistance: affecting the pump body's ability to resist media scouring.
1. Impact of abrasion on performance
Media characteristics: media containing sediment (such as mine drainage), suspended solids (sewage treatment) will accelerate the wear of the pump body.
Performance degradation: The flow path of the pump body becomes rough due to wear, resulting in increased hydraulic losses (efficiency loss of 5-10%), and may cause vibration (due to irregular flow paths).
Case: a coal mine drainage pump using cast iron pump body, conveying sewage containing 3% sediment, half a year after the runner wall thickness wear 1 ~ 2mm, head decreased by 15%.
2. Wear-resistant material selection strategy
High-chromium cast iron (such as Cr20): hardness HRC55 ~ 60, anti-abrasive wear ability is 3 ~ 5 times that of ordinary cast iron, suitable for solid particles containing media (such as mining, metallurgy).
Ceramic coating: Zirconium oxide (ZrO₂) is sprayed on the inner wall of the cast iron pump body to form a wear-resistant layer (thickness 0.5~1mm), the cost of which is 30% lower than that of the whole high-chromium cast iron, and it is suitable for small and medium-sized pumps.
Third, corrosion resistance: to ensure media compatibility and life expectancy
1. Corrosion type and material failure mode
Chemical corrosion: acidic media (such as pH <4 sewage) will lead to cast iron pump body rust, stainless steel (304) in the chlorine-containing ions (Cl-> 200ppm) environment may occur pitting corrosion.
Electrochemical corrosion: different materials in contact (such as cast iron pump body with copper impeller) to form a primary cell, accelerating the corrosion of the pump body.
Performance impact: corrosion leads to thinning of the pump body wall thickness (e.g. corrosion rate > 0.5mm per year), and eventual leakage; at the same time, the surface of the flow path is roughened, and the efficiency is reduced.