1045 is often listed as a "high carbon steel" but at 0.45% carbon it is listed as a medium carbon steel. In practical terms this means that a sword made of it is a lot more likely to take a set, or bend than its higher carbon content counterparts because of it's limited capacity to harden on quenching.
Heat treatment for any functional 1045 steel is of prime importance because of this but even on a well heat treated sword, the possibility of a bend is still high on a bad cut and edge retention is not fantastic.
As with all carbon steels, rusting will occur unless the blade is kept clean, dry and oiled when not in use.
A table showing the AISI standard for 1040
|Carbon, C||0.420 - 0.50 %|
|Iron, Fe||98.51 - 98.98 %|
|Manganese, Mn||0.60 - 0.90 %|
|Phosphorous, P||≤ 0.040 %|
|Sulfur, S||≤ 0.050 %|