What is 41L40 Steel & 41L40 Steel Properties - 41L40 vs 4140

The name of alloys is often closely related to their chemical composition and treatment process, how to distinguish similar alloy grades? In this article, we’ll introduce what is 41L40 steel and 41L40 steel properties, also explore the difference between 4140 and 41L40 alloy.

What is 41L40 Steel?

Steel alloy 41L40 is free-machining chromium-molybdenum steel with a lead addition, which makes it easy to machine, but also results in lower impact strength than other steel alloys. 41L40 steel has high strength, high hardenability, high ductility, high wear resistance, good toughness, and resists stress and creep at prolonged high temperatures. 41L40 can be heat treated and annealed. 41L40 is ideal for parts that require high wear resistance and toughness. It is often used to make shafts, bolts, couplings, tractor & trailer axles, spindles, and tooling with CNC milling/turning technologies. Junying can provide quality CNC machining parts from 41L40 Steel.

41L40 Grade Alloy Composition

Carbon: 0.38-0.45

Manganese: 0.50-0.80

Silicon: 0.17-0.37

Chromium: 0.90-1.20

Molybdenum: 0.15-0.25

Lead: 0.15-0.35

Phosphorus (max): 0.035

Sulfur (max): 0.035

Nickel (max): 0.030

Copper(max): 0.030

41L40 Steel Properties

Tensile strength: 95,000 – 105,000 psi

Yield strength: 85,000 – 95,000 psi

Elongation in 2” (%): 15-25

Reduction of area (%): 50-60

Brinell Hardness (BHN): 200-230

41L40 vs 4140 - Difference Between 4140 and 41L40

The AISI system uses a letter along with the digit to denote the steelmaking process, the prefix “C” indicates open-hearth furnace, electric arc furnace or basic oxygen furnace, “E” means electric arc furnace steel, while “L” within the alloy grade name denotes lead as an added ingredient, so 41L40 is the lead added version of the common grade 4140 for improving the machinability.

The leaded grade has significantly improved machinability, but not suitable to be used in applications over 400°F because the elevated temperatures cause lower ductility. 41L40 can be heat treated the same as a standard 4140 to achieve similar hardness and strength. Impact toughness is somewhat lower for the leaded grade for hardnesses exceeding 35 HRC.

What type of steel is 4140? Steel 4140 (AISI 4140) is a low alloy steel containing chromium, molybdenum, and manganese. It is commonly used in a wide range of industries due to its excellent performance such as toughness, high fatigue strength, and abrasion and impact resistance, typical applications including structural tubing, bicycle frames, gas bottles, firearm parts, flywheel components, and more. Let’s explain the designation system of the SAE steel family. Carbon steels and alloy steels are designated a four-digit number, whereby the first digit indicates the main alloying element(s), the second digit indicates the top-grade element, and the last two digits indicate the amount of carbon. 4xxx series steel is a type of Molybdenum steels, while 41xx series grades are Chromium-molybdenum steels, 41xx steel is specified by Society of Automotive Engineers.

4140 Steel Properties

Density: 7.85 g/cm3

Melting point:1416 ℃

Tensile strength: 95000 psi

Yield strength: 60200 psi

Elastic modulus: 27557-30458 ksi

Hardness, Brinell: 197

Hardness, Rockwell B: 92

Hardness, Rockwell C: 13

Hardness, Vickers: 207