44W/1018/1045 Hot Rolled Round Bars (ASTM A-29, ASTM A576)

The designation 44W/1018/1045 Hot Rolled refers to a group of three different carbon steel grades, all supplied in the Hot Rolled (HR) condition. They are grouped together because they represent the most common and versatile low-to-medium carbon steels used in general fabrication and machinery, often chosen based on the required strength.

Hot Rolling is the process where steel is formed into bars while it is at a high temperature.

• Surface Finish: Characterized by a rough surface and a layer of mill scale (a bluish-black iron oxide layer).
• Dimensional Tolerance: Has wider tolerances and is less precise than cold-drawn (CD) bars.
• Strength: The mechanical properties (strength and hardness) are typically lower than the cold-drawn versions of the same grade but still suitable for structural and general purposes.

Comparison of Steel Grades

The main difference between the three grades is the carbon content, which dictates the strength, weldability, and heat treatment response.

44W Steel (Canadian Structural Standard)

• Identity: 44W is a Canadian structural steel standard (CSA G40.21) that is the functional equivalent of the U.S. grade ASTM A36.
• Properties: It is a readily weldable and easily formed mild steel. The name "44W" indicates a minimum yield strength of 44 ksi (kilo-pounds per square inch) for thinner sections, which is slightly higher than the 36 ksi minimum for A36.
• Application: Used extensively in general fabrication and structural construction where high strength and good weldability are essential.

1018 Steel (Low-Carbon)

• Identity: An extremely common low-carbon steel.
• Properties: Due to its low carbon content, it offers excellent weldability and the best machinability of the three grades. It is ductile (can be bent/shaped easily) but has the lowest inherent strength.
• Heat Treatment: It cannot be hardened throughout, but it is the top choice for case hardening (carburizing), where only a hard, wear-resistant surface layer is desired over a tough core.

1045 Steel (Medium-Carbon)

• Properties: The medium carbon content makes it significantly stronger and harder than 1018 and 44W in the as-rolled condition. Its machinability is good, but not as easy as 1018.
• Heat Treatment: It is a through-hardening steel; it responds well to quenching and tempering to achieve high strength and hardness deep into the bar's cross-section. Welding requires preheating and post-weld heat treatment to prevent cracking.