A general-purpose medium carbon steel material suitable for medium-strength mechanical parts, shaft parts, connectors, quenching and tempering parts, wear-resistant parts, fixtures and fixtures, ordinary gears, and mechanical structural parts.
45# is a commonly used medium-carbon high-quality carbon structural steel, characterized by good strength, hardness, wear resistance, and machinability, making it one of the most widely used steels in mechanical manufacturing. After quenching and tempering, quenching, tempering, or surface quenching, 45# steel can achieve better overall mechanical properties and is commonly used in shaft parts, gears, connecting rods, pins, sleeves, fixtures and jigs, mechanical structural parts, and medium-load metal parts. Compared to 20# steel, 45# steel has higher strength and hardness; Compared to alloy steels like 40Cr, 45# steel is less expensive, but its hardenability, overall strength, and fatigue performance are relatively limited.
By focusing on application scenarios, boundaries of advantages, and non-recommended scenarios, it helps sales, customer service, and quoting staff quickly determine whether the material meets current part requirements.
It has good strength, hardness, wear resistance superior to low-carbon steel, good machinability, can be strengthened by heat treatment, has relatively low material costs, has a wide range of applications, and is suitable for shaft parts, gear blanks, connectors, and medium-load structural components.
Shaft parts, pins, sleeves, connecting rods, gear blanks, sprockets, screws, connectors, fixtures and jigs, mechanical brackets, ordinary transmission parts, mold auxiliary parts, hardware, medium-load structural parts, quenched and tempered mechanical parts, surface quenched and wear-resistant parts.
High-strength heavy-duty parts, high-impact toughness parts, highly corrosive environment parts, long-term exposed outdoor parts, food direct contact parts, medical implants, strong welded structural parts, high-elasticity snap-fit parts, high-precision high-speed gears, metal parts requiring rust-free maintenance, and structural parts with high lightweight requirements.
The following parameters come from product information and material knowledge fields, used for design review, quotation communication, and preliminary judgment before material selection.
| Material positioning | A general-purpose medium carbon steel material suitable for medium-strength mechanical parts, shaft parts, connectors, quenching and tempering parts, wear-resistant parts, fixtures and fixtures, ordinary gears, and mechanical structural parts. |
|---|---|
| Precision performance | 45# suitable for CNC turning, milling, drilling, tapping, grinding, and finishing after heat treatment. CNC machining can achieve better dimensional accuracy; After heat treatment, dimensional accuracy is affected by deformation, and key dimensions usually require grinding or secondary finishing. It is recommended to mark tolerances and machining requirements separately for shaft parts, hole positions, threads, mating surfaces, and wear-resistant surfaces. |
| Dimensional tolerances | Conventional dimensional tolerances for CNC machining 45# can be referenced as ± 0.02mm to ±0.10mm, while ordinary structural parts can be evaluated at ± 0.10mm to ±0.20mm; If parts require quenching and tempering, quenching, high-frequency quenching, or surface quenching, dimensional changes or deformation may occur after heat treatment. It is recommended to heat treat key dimensions before finishing. These values represent the standard reference range and do not guarantee absolute tolerances for all structures. Actual confirmation must be based on process, dimensions, structure, heat treatment, and post-processing. |
| Minimum Wall Thickness | The wall thickness of ordinary CNC machined structures is recommended to be no less than 0.8mm-1.0mm. Small non-stressed areas can be further optimized according to structure and processing methods, but it is not recommended to make large areas that are too thin. Areas requiring heat treatment, tapping, load-bearing, wear resistance, or assembly should be appropriately thickened to avoid processing deformation, heat treatment deformation, cracking, or insufficient strength. |
| Recommended wall thickness | For ordinary structural parts, 1.5mm-3.0mm is recommended; shaft parts, mounting seats, threaded connection points, fixtures, fixtures, wear-resistant surfaces, and load-bearing positions are recommended to be above 2.0mm; for parts requiring quenching and tempering, quenching, or surface quenching, increase machining allowance based on deformation risk and reserve grinding or finishing allowance at key dimensional positions. |
| Minimum aperture | CNC machining can achieve smaller hole diameters, but controlling deep small holes and hole position accuracy after heat treatment is more challenging. For general designs, the recommended aperture is no less than 1.0mm. For precision holes, threaded holes, positioning holes, pin holes, and fitting holes, it is recommended to reserve machining allowance. If necessary, drill, ream, boring, or grinding should be performed after heat treatment. |
| Assembly clearance | For precision metal assembly, one side can be reserved at 0.02mm-0.10mm according to fitting requirements; for ordinary plug-in and assembly, it is recommended to reserve 0.10mm-0.30mm per side. If parts require heat treatment, blackening, electroplating, galvanizing, powder spraying, painting, or rust prevention, increase assembly allowance by combining heat treatment deformation and surface treatment thickness to avoid overtightening or surface scratches. |
| Detailed performance | 45# steel is suitable for machining holes, grooves, steps, chamfers, threads, shaft shoulders, positioning surfaces, keyways, wear-resistant surfaces, and ordinary mechanical structural details. Under CNC machining, detail performance is good, and after heat treatment, key surface quality can be improved through grinding. Small text, logos, and markings are recommended to be achieved through laser marking, engraving, stamping, or etching. |
| Surface effect | The original surface of 45# steel is usually gray-black or silver-gray metallic surface, and may have oxide scale, knife marks, scratches, or rust spots. After grinding and polishing, a relatively smooth metal surface is obtained; after blackening, a black rust-resistant appearance is achieved; after galvanizing or electroplating, a silver-white or glossy metallic effect can be achieved; after painting or powder spraying, multiple colors and better protection can be achieved. If long-term appearance stability is desired, reliable anti-rust treatment or switching to stainless steel is recommended. |
Based on material characteristics and suitable product ranges, customer needs are broken down into easier application directions to determine.
Shaft parts, pins, sleeves, connecting rods, gear blanks, sprockets, screws, connectors, fixtures and jigs, mechanical brackets, ordinary transmission parts, mold auxiliary parts, hardware, medium-load structural parts, quenched and tempered mechanical parts, surface quenched and wear-resistant parts.
A general-purpose medium carbon steel material suitable for medium-strength mechanical parts, shaft parts, connectors, quenching and tempering parts, wear-resistant parts, fixtures and fixtures, ordinary gears, and mechanical structural parts.
45# is a medium-carbon steel, with better strength, hardness, and wear resistance than low-carbon steels like 10# and 20#, making it suitable for parts that require certain load-bearing capacity, wear resistance, and mechanical strength. It can improve performance through heat treatments such as quenching and tempering, quenching, tempering, and high-frequency quenching, but its weldability and plasticity are inferior to low-carbon steel. As ordinary carbon steel, it is prone to rust in exposed environments and usually requires surface protection such as blackening, electroplating, galvanizing, painting, phosphating, and rust prevention oil.
Based on wall thickness, hole position, assembly clearance, dimensional tolerances, and material usage risks, determine in advance whether the part structure is suitable for 45#.
Post-processing of 45# affects appearance, dimensions, hole position, assembly clearance, and usage validation results, and should be explained in advance during quotation, DFM review, and sample confirmation stages.
Post-processing should focus on appearance display, dimensional fitting, connection assembly, and testing verification. Parts involving assembly positions need to be reserved in advance for machining, coating, and trial assembly allowances.
For common issues such as threads, snaps, strength, temperature resistance, and weather resistance, identify in advance whether the material needs to be replaced or if another processing method should be used.
When customer demand exceeds 45# material boundaries, it is necessary to combine strength, temperature resistance, toughness, long-term stability, and mass production goals to promptly recommend alternative materials or processing technologies.
If higher strength, toughness, and hardenability are required, 40Cr, 42CrMo, or other alloy steels can be chosen; If better weldability and formability are required, 20# steel or 10# steel can be chosen; If better corrosion resistance is required, 304 stainless steel, 316 stainless steel, or surface galvanized treatment can be chosen; If you need a lighter weight, you can choose the 6061 Aluminum Alloy or 7075; If higher wear resistance and mold performance are required, mold steel or surface heat-treated steel can be chosen.
If customers require higher strength, better hardness, general wear resistance, and lower material costs,45# is a very common choice. If customers need to use it outdoors for extended periods in humid or corrosive environments, it is not recommended to use exposed 45# steel directly; stainless steel should be chosen or reliable surface protection should be added. If customers require higher fatigue strength, heavy load capacity, or better heat treatment stability, further evaluation should be made of 40Cr, 42CrMo, alloy steel, or mold steel.
After uploading 3D/2D drawings and supplementing materials, quantities, tolerances, surface treatments, and delivery requirements, XPartsLab will provide next steps in 3D printing manufacturability, cost, and delivery pathways.
