Alloy Structural Steel Round Bar
Introduction:
Alloy structural steel round bar integrates domestic low-alloy high-strength steel, manganese-boron alloy steel, silicon-manganese high-strength steel, chromium-molybdenum tempered steel, carburizing alloy steel and European standard equivalent grades. Adopt EAF smelting, LF ladle refining, VD vacuum degassing and precise controlled hot rolling production process. By adding Mn, Si, Cr, Mo, B, Ti, V and other micro-alloy elements, the steel obtains excellent hardenability, balanced strength & toughness, outstanding fatigue resistance, stable temper resistance and reliable weldability.
Product Overview
Diameter range covers ø12–300mm, complete mainstream grades: Q355, Q390, Q420, Q460, St52-3, S355Jo, 30Mn2, 40Mn2, 27SiMn, 42CrMo, 42CrMo4, 20MnVB, 20MnTiB, 20Cr, 40Cr, 20CrMo, 41Cr4, 35CrMo, 20CrMnTi, 30CrMnTi, 30CrMnSi, 35CrMnSi, 40MnB.
Multiple delivery states are available: hot-rolled black round bar, normalized bar, full annealed soft bar, quenched & tempered bar, peeled precision bright bar. Widely applied in automobile transmission components, heavy-duty shafts, gear forgings, engineering machinery load-bearing parts, petroleum drilling fittings, wind power main shafts, bridge & factory building steel structures, export mechanical and auto supporting parts.
Representative Grades
|
Grade |
Executive Standard |
Alloy Classification |
Core Performance & Application |
|
Q355/Q390/Q420/Q460 |
GB/T 1591-2018 |
Domestic HSLA low-alloy high-strength steel |
V/Nb/Ti micro-alloyed, high yield strength, good cold bending & weldability; workshop frames, bridge supports, mining equipment, heavy truck structural parts |
|
St52-3 / S355Jo |
DIN 17100 / EN 10025-2 |
European low-alloy structural steel |
S355Jo guarantees 0℃ impact toughness ≥27J; St52-3 performance equivalent to Q355B; overseas engineering frames, cold-formed load-bearing parts |
|
30Mn2 / 40Mn2 / 40MnB |
GB/T 3077-2015 |
Mn-B low-alloy steel |
Trace boron greatly improves hardenability, cost-effective alternative to partial Cr steel; medium-load connecting rod blanks, general shaft forgings, heavy bolt raw materials |
|
27SiMn |
GB/T 3077-2015 |
Si-Mn high tensile wear-resistant steel |
High tensile strength and impact resistance; hydraulic cylinder blanks, heavy mining structural forgings |
|
35CrMo / 42CrMo / 42CrMo4 |
GB/T 3077 / EN 10083-3 |
Cr-Mo tempered steel |
Excellent temper stability & low-temperature toughness; crankshafts, wind power main shafts, drill collars, high-pressure valve bodies |
|
20CrMo / 41Cr4 |
GB/T 3077 / EN 10083-3 |
Medium-low carbon Cr alloy steel |
Dual-purpose for carburizing and quenching & tempering; miniature gears, piston pins, export high-strength fasteners |
|
20MnVB / 20MnTiB |
GB/T 3077-2015 |
Fine-grain B-Ti carburizing steel |
Ultra-fine grain, ultra-high fatigue strength; automobile gearbox gear blanks, transmission shaft forgings |
|
20Cr / 40Cr |
GB/T 3077-2015 |
General chromium alloy structural steel |
Stable comprehensive mechanical properties, wide applicability; conventional gears, steering knuckles, half shafts, fixture blanks |
|
20CrMnTi / 30CrMnTi |
GB/T 3077-2015 |
Cr-Mn-Ti carburizing steel |
Uniform carburized layer, stable impact resistance; heavy-duty automobile gears, gear ring forgings, large reducer gears |
|
30CrMnSi / 35CrMnSi |
GB/T 3077-2015 |
Multi-alloy ultra-high strength steel |
Outstanding impact resistance; high-pressure precision forgings, aerospace structural components, heavy shock-resistant parts |
Grade Description
-
01
Low-alloy high-strength series (Q355~Q460, St52-3, S355Jo): Micro-alloyed with vanadium, niobium and titanium, high yield strength, good cold bending and welding performance, mainly used for large load-bearing engineering structures and export mechanical frames.
-
02
Mn-B series (30Mn2,40Mn2,40MnB): Manganese improves basic strength, trace boron sharply enhances hardenability, can partially replace chromium alloy steel to cut production costs.
-
03
Cr-Mo tempered steel (35CrMo,42CrMo,42CrMo4): Chromium improves hardness and wear resistance, molybdenum eliminates temper brittleness, suitable for heavy-load power core components under high temperature and alternating stress.
-
04
Carburizing steel (20Cr,20CrMo,20MnTiB,20CrMnTi,30CrMnTi): Low carbon alloy steel, after carburizing heat treatment to form hard wear-resistant surface while retaining high-toughness core, special raw material for all kinds of transmission gears.
-
05
30CrMnSi/35CrMnSi: Silicon-chromium-manganese composite multi-alloy steel with ultra-high strength and strong impact resistance, used for special high-pressure and shock-resistant precision forgings.
Product Specifications
|
Item |
Specific Parameters |
|
Product Form |
Hot rolled round bar;Forged round bar;Peeled precision bright bar |
|
Diameter Range |
ø12 mm – ø300 mm |
|
Standard Length |
3m / 6m / 9m / 12m; customized fixed-length cutting available |
|
Delivery Condition |
Hot rolled black oxide scale / Normalized / Full annealing / Quenched & tempered / Peeled & ground finished |
|
Surface State |
As-rolled oxide skin; shot blasting, surface scarfing & polishing optional |
|
Size Tolerance |
Comply with GB/T 702, EN 10060 standard dimensional tolerance requirements |
|
Straightness |
Standard hot rolled ≤3mm/m；Precision peeled bar ≤1.5mm/m |
|
Internal Quality Standard |
Low central segregation, minimal shrinkage cavity & looseness, fine uniform grain, strictly limited S/P and non-metallic inclusions |
Core Advantages
1. Complete Global Grade Matrix: Cover domestic HSLA steel, Mn-B alloy, Cr-Mo tempered steel, Cr-Mn-Ti carburizing steel and European standard equivalent grades, fully match carburizing, quenching & tempering, nitriding all heat treatment processes, realize one-stop raw material supply for construction, automobile, petroleum, machinery and export manufacturing industries.
2. Ultra-High Metallurgical Purity: Triple smelting process EAF+LF+VD removes gas and harmful impurities inside steel; stable internal metallographic structure, tiny mechanical performance fluctuation between different heats and batches.
3. Balanced Comprehensive Mechanical Performance: Scientific alloy matching achieves high strength, high toughness, excellent fatigue resistance and temper stability; large-diameter bars maintain uniform hardness after secondary forging and machining without internal layering.
4. Full Diameter Coverage ø12–300mm: Small-diameter bars for miniature precision parts and small gear blanks; large-diameter bars for heavy-duty transmission shafts, large gear ring forgings and engineering load-bearing structural blanks.
5. Wide Downstream Process Adaptability: Suitable for hot forging, cold bending, CNC machining, welding, piercing and other processing routes; normalized/annealed bars save secondary heating energy consumption for downstream manufacturers.
6. Diversified Custom Deep Processing Support: Provide surface peeling & grinding, softening normalization, fixed-length cutting, shot blasting rust removal and full-set non-destructive flaw detection customized services.
Main Application Fields
-
Construction, Bridge & Heavy Engineering Machinery
Q355/Q390/Q420/Q460/St52-3/S355Jo round bars for factory steel frames, bridge support beams, mining equipment brackets, heavy transport vehicle structural parts, overseas engineering cold bending components.
-
Automobile Manufacturing Forging Raw Material
20CrMnTi/20MnTiB gear blanks, 42CrMo/35CrMo crankshaft & connecting rod blanks, 40B/40Cr medium-strength fastener forgings, steering knuckle semi-finished products.
-
Petroleum & New Energy Equipment
Cr-Mo series bars for drill collars, wind power main shaft blanks, hydraulic piston rods, high-pressure valve bodies; 27SiMn specially used for hydraulic cylinder blank production.
-
General Mechanical Manufacturing
40Cr/20CrMo shaft blanks, reducer gear forgings, heavy-duty pin and mold blank raw materials; 30CrMnSi/35CrMnSi for aerospace high-pressure impact-resistant structural parts.
-
Export Machinery & Auto Supporting Parts
European standard grades including 42CrMo4, 41Cr4, S355Jo, St52-3 for overseas equipment and automobile factory supporting raw materials.
-
Heavy-Duty Forging & Precision Machining Components
Medium-large diameter alloy bars for large gear ring forgings, shock-resistant mechanical parts, fixture load-bearing structural blanks.
Packaging & Services
- 1. Executive Standards: GB/T 1591-2018, GB/T 3077-2015, EN 10025-2, EN 10083-3, DIN 17100.
- 2. Full Inspection Items: Melting chemical composition analysis, dimensional inspection, surface defect detection, tensile test, impact test, hardness test, macrostructure low-fold examination, non-metallic inclusion rating; optional ultrasonic flaw detection (UT), magnetic particle inspection (MPI).
- 3. Certification Documents: EN10204 MTC 3.1 mill test certificate attached per batch, complete heat number composition & mechanical property reports; SGS/BV/TÜV third-party inspection certification available.
- 4. Packaging & Shipment: Steel wire bundled, waterproof tarpaulin covering, anti-collision plastic end caps; support bulk cargo vessel and full container transportation.
- 5. MOQ: 1 ton per single grade; mixed grades & mixed diameter sizes container loading acceptable.
- 6. Value-added Services: Surface scarfing & grinding, softening normalization, fixed-length cutting, shot blasting rust removal, full-set non-destructive flaw detection, customized heat treatment processing.
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Contact Us
- WhatsApp: +86-185 9567 2991
- Email: martinliu@rongtianmetal.com
- Tel: +86-185 9567 2991
- Address: 8F, Bldg 2, Jinke Zhihui Valley No. 65 Hongyuan Rd., Jinshui Dist. Zhengzhou, China.
