Selection of Propeller Material for Ships in Ice area
At present, the materials of marine propellers are mainly copper alloy and stainless steel. Aluminum bronze is the preferred material in copper alloy which has excellent resistance to stress corrosion cracking, corrosion fatigue, cavitation corrosion, erosion and marine fouling, while stainless steel materials are not as good as manganese aluminum bronze. See the table below for a comparison of the mechanical properties of manganese-aluminum bronze and stainless steel.
tensile strength （MPa） | Yield Strength （MPa） | Brinell hardness (HB) | |
Manganese Aluminum Bronze （ZCuAl8Mn12Fe3Ni2 | ≥645 | ≥280 | ≥187 |
Stainlesssteel (1Cr18Ni9Ti) | ≥550 | ≥200 | ≥157 |
According to the data in the table, it can be seen that the tensile strength and yield strength of manganese aluminum bronze are better than stainless steel materials (the stainless steel material in the table is 1Cr18Ni9Ti as an example), and the Brinell hardness of stainless steel materials is greater than manganese aluminum bronze., according to relevant data, propellers using conventional manganese-aluminum-bronze materials meet the requirements of Class B1.
The thickness of the reinforced ice area needs to be increased by 28%; and the CCS classification society regulations specifically stipulate the blade edge thickness of the propeller sailing in the ice area: "The edge thickness measured at a distance of 1.25t from the edge (t is the blade thickness) shall be Not less than 50% of the thickness of the leaf tip..." (the above t is the thickness after strengthening by the ice region);
The propellers used in the Russian "Olatov" series fishing boats are made of manganese aluminum blue. Copper, its operating area is ice area operation.
In summary, since the corrosion resistance of manganese-aluminum bronze is better than that of stainless steel, according to the rules of classification societies and related data, no matter whether it is manganese-aluminum bronze or stainless steel, it will not affect its strength after being strengthened in ice areas. Therefore, copper alloy (manganese-aluminum alloy) is recommended for marine propellers in ice areas. bronze)
