As a reliable Multi Shape Cold Drawn Bar Supplier, SHANDONG LE REN SPECIAL STEEL CO., LTD. specializes in high-performance SAE 4140 steel bar with full custom cold-finished profiles and one-stop deep processing service for global industrial clients. Our factory integrates cold drawing, heat treatment, precision polishing and surface coating workshops, supplying standardized and customized alloy steel bars to machinery, automotive, construction and fitness manufacturers worldwide with complete inspection certificates and stable stock supply.
SAE 4140 is a classic Cr-Mo alloy steel celebrated for balanced hardenability, toughness and fatigue resistance. Its standard chemical composition (weight percentage):
| C |
Si |
Mn |
S |
P |
Cr |
Mo |
| 0.35-0.45 |
0.15-0.35 |
0.60-0.90 |
0.035 max |
0.035 max |
0.90-1.20 |
0.15-0.35 |
We conduct strict raw material spectral testing for every batch of our Cold Drawn Steel Bar series, including premium cold drawn round bar, premium cold drawn square steel bar, cold drawn flat steel bar and cold drawn hexagonal steel bar, to stabilize element ratios and avoid machining cracking or uneven hardness. All these cold finished profiles fall under our Bright Steel Bar product line with oxide-free mirror smooth surfaces.
2. Outstanding Mechanical Properties
Unprocessed annealed SAE 4140 steel bar delivers smooth machinability, while quenched and tempered steel bar finished from this grade achieves premium mechanical indicators:
| Tensile strength |
Yield strength |
Elongation rate |
Reduction of area |
Hardness scope |
| 900-1200 MPa |
750-1000 MPa |
12% min |
55% min |
22HRC-42HRC |
We can adjust sae 4140 steel bar tensile strenth and hardness by quenching and tempering. The max tensile strength of sae 4140 steel round bar can reach 2000MPa max.
3. Versatile Heat Treatment Performance
SAE 4140 steel bar adapts to all mainstream thermal processing techniques:
Annealing: Soften raw blanks for cold drawing and precision cutting;
Normalizing: Refine internal grain structure to eliminate internal stress;
Quenching & Tempering: Fabricate high-strength quenched and tempered steel bar for heavy-load structural parts;
Surface hardening: Nitriding, carburizing or hard chrome plating to produce wear-resistant hard chromed steel bar.
All our cold finished profiles support pre-factory heat treatment or post-processing thermal treatment following client drawings.
4. Precision Cold Processing Advantages
We produce SAE 4140 cold drawn steel bar via multi-pass cold drawing, straightening and surface polishing, covering premium cold drawn round bar, premium cold drawn square steel bar, cold drawn flat steel bar and cold drawn hexagonal steel bar.
1) Ultra-tight dimensional tolerance, eliminating secondary grinding for most precision machining projects;
2) Smooth oxide-free surface, classified as standard bright steel bar;
3) High straightness and consistent cross-section to cut down clients’ secondary processing costs;
We further deep-process cold drawn blanks into turned ground and polished steel round bar, threaded steel bar and steel tie rod with precise thread standards and smooth surfaces. We also customize SAE 4140 olympic weightlifting bar with exclusive knurling and anti-rust surface treatment for fitness equipment manufacturers.
5. Wide Application Range
General machinery: Gear shafts, hydraulic piston rods, connecting shafts, heavy machine accessories (premium cold drawn round bar & turned ground and polished steel round bar);
Construction & heavy fasteners: high-strength threaded steel bar, steel tie rod, structural support brackets (premium cold drawn square steel bar, cold drawn flat steel bar);
Automotive manufacturing: Axles, crankshafts, brake assemblies, transmission components (quenched and tempered steel bar);
Mold & fixture hardware: cold drawn hexagonal steel bar for bolt blanks, tool fixtures;
Fitness equipment: Custom olympic weightlifting bar with hard chromed steel bar surface for anti-corrosion and abrasion resistance;
Petroleum & engineering machinery: High-load wear-resistant components adopting hard chromed steel bar;
Intelligent robotics: high strength steel humanoid robot harmonic shaft, joint transmission core parts, robot reducer shafts, lightweight high-torsion robot structural spindles;
6. Global Market Analysis
SAE 4140 alloy steel bar remains one of the most widely traded alloy steel grades worldwide, with steadily rising demand across Europe, North America, Southeast Asia, South Africa, South America and Australia. It replaces low-carbon steel for medium & heavy load components thanks to its perfect balance of mechanical performance and cost.
7. Our Factory Strength – SHANDONG LE REN SPECIAL STEEL CO., LTD.
We are an experienced Multi Shape Cold Drawn Bar Supplier with more than 15 years of special steel production and export experience, focusing on SAE 4140 steel bar and other alloy & carbon bright steel products.
Complete product portfolio: premium cold drawn round bar, premium cold drawn square steel bar, cold drawn flat steel bar, cold drawn hexagonal steel bar, Bright Steel Bar, Turned Ground and Polished Steel Round Bar, hard chromed steel bar, quenched and tempered steel bar, Threaded Steel Bar, Steel Tie Rod and Olympic Weightlifting Bar;
Full independent production chain: In-house cold drawing lines, heat treatment workshops, CNC turning & polishing machines, chrome plating production line and threading processing workshop. Our high-precision polishing workshop is specially equipped to process blanks for High Strength Steel Humanoid Robot Harmonic Shaft with micron-level tolerance;
Strict quality inspection: Full MTC material test certificates supplied for every batch; third-party inspection by SGS, BV and other authorities is acceptable;
Flexible order service: Standard sizes in stock, custom cut lengths, customized heat treatment, surface coating, threading and OEM deep processing, including custom blank for robot harmonic shafts;
Convenient export logistics: Close to Qingdao Port to guarantee fast delivery, factory direct competitive prices, professional foreign trade team supporting OEM & ODM bulk orders.
FAQ Section
Q1: What shape options do you offer for SAE 4140 steel bar?
A1: As a professional Multi Shape Cold Drawn Bar Supplier, we provide all mainstream Cold Drawn Steel Bar profiles: premium cold drawn round bar, premium cold drawn square steel bar, cold drawn flat steel bar, cold drawn hexagonal steel bar. We also support deep processing into Turned Ground and Polished Steel Round Bar, Threaded Steel Bar, Steel Tie Rod, hard chromed steel bar, quenched and tempered steel bar and custom Olympic Weightlifting Bar. All shapes belong to our Bright Steel Bar product line with smooth bright surfaces.
Q2: Can SAE 4140 cold drawn steel bar be heat treated?
A2: Absolutely. SAE 4140 has excellent heat treatment performance. We can supply annealed raw blanks, normalized bars, or finished quenched and tempered steel bar with target hardness. We also provide surface treatment including hard chrome plating to produce hard chromed steel bar for wear-resistant usage.
Q3: What is the tolerance of your cold drawn profiles?
A3: Our Cold Drawn Steel Bar series (premium cold drawn round bar, premium cold drawn square steel bar, cold drawn flat steel bar, cold drawn hexagonal steel bar) achieves tight dimensional tolerance up to h9/h11 grade, classified as high-precision Bright Steel Bar. Turned Ground and Polished Steel Round Bar can reach h7/h8 tolerance for ultra-precision machining.
Q4: Do you supply material test certificates for SAE 4140 steel bar?
A4: Yes. Every shipment of our cold drawn hexagonal steel bar, quenched and tempered steel bar and all other products comes with official MTC (Material Test Certificate) covering chemical composition and mechanical properties. Third-party inspection such as SGS/BV is available upon your request.
Q5: What industries use your SAE 4140 Threaded Steel Bar and Steel Tie Rod?
A5: Our Threaded Steel Bar and Steel Tie Rod made of SAE 4140 are widely used in construction formwork, bridge engineering, heavy machinery assembly and mining equipment. Meanwhile, cold drawn hexagonal steel bar serves as ideal blank for high-strength bolts, while premium cold drawn round bar and Turned Ground and Polished Steel Round Bar are popular for automotive shafts and hydraulic parts.
Q6: What are your delivery advantages for bulk SAE 4140 steel bar orders?
A7: Our factory is located near Qingdao Port with stable stock of standard-size premium cold drawn round bar, premium cold drawn square steel bar and cold drawn hexagonal steel bar for fast shipment. We have independent production lines for heat treatment, chrome plating and threading to shorten lead time for custom quenched and tempered steel bar, Threaded Steel Bar and hard chromed steel bar orders.
Q7: Is SAE 4140 cold drawn steel bar easy to machine?
A8: Annealed SAE 4140 Bright Steel Bar including premium cold drawn round bar and cold drawn hexagonal steel bar shows great machinability for cutting, drilling, tapping and bending. After quenching and tempering, the quenched and tempered steel bar becomes high-strength and suitable for heavy-load finished parts.
