The 4145 type of steel comes from the same family( Chromium-Molybdenum Series) of the 4140 steel.
The very small difference is their percentage of carbon content.4145 has carbon content with 0.43-0.48%,0.05% higher than 4140 Steel.Due to the slight difference in carbon content, the strength of 4145 steel is slightly higher than that of 4140 steel.
With suitable heat treatment, 4140 and 4145 steel have good comprehensive performance,and are widely used in the oil and gas industry.Learn More