Description: BBN steel is a well-known steel manufacturer and service provider in China, GB/T 3077 30CrMo Alloy Steel Plate is our superior product, we are favored by customers with high quality, competitive price and excellent service
Payment Terms: L/C, T/T, D/P, Western Union, Paypal, Money Gram
GB/T 3077 30CrMo is a Chinese chromium-molybdenum alloy structural steel. The leading digits "30" denote its medium carbon level (about 0.30%), which combined with chromium and molybdenum gives high strength, good hardenability and stable toughness after quenching and tempering. It is the established plate grade for 8.8S and 10.9S high-strength bolts as well as highly loaded mechanical parts.
Because the alloy band is wide, 30CrMo plate is normally ordered with the heat-treatment condition and the required mechanical values written into the purchase order. BBN supplies it with full composition and mechanical testing, certified on the mill test certificate (MTC) of each heat.
785 MPaMin. Yield ReLSource data sheet, both thickness bands
930 MPaMin. Tensile RmSource data sheet, both thickness bands
SCM430Nearest International MatchJIS G4053 per source data sheet
02Technical Specifications
Standard supply programme for 30CrMo alloy steel plate as published for this product page.
Promptly from stock; custom production 10 – 40 working days
Lead Time by Quantity
1 – 10 t: 5 days · 10 – 50 t: 10 days · > 50 t: negotiable
Certification
Mill Test Certificate (MTC) available; third-party inspection supported
Payment Terms
T/TL/C at sightother terms negotiable per order
Processing Services
Custom cutting to length / width, heat treatment to your requirement, machining support
Note: The dimensional range above is the mill rolling programme, not a guarantee that every thickness can be combined with every width and length — please send the size you need and we confirm from the rolling schedule. Payment terms published elsewhere on this product page additionally list L/C, T/T, D/P, Western Union, Paypal and Money Gram; the terms finally applied are those written into the order. Thickness, width and length tolerances follow GB/T 3077 and the agreed order specification.
03Grade Designation & Meaning
The Chinese alloy structural steel designation encodes the approximate carbon content first, followed by the alloying elements.
30
30 — Carbon Level
Stands for a nominal carbon content of about 0.30% (100 × C%); the GB/T 3077 band for 30CrMo is 0.26 – 0.34%.
Cr
Cr — Chromium
Chromium raises hardenability, strength and temper resistance, and gives moderate oxidation resistance at elevated temperature.
Mo
Mo — Molybdenum
Molybdenum suppresses temper embrittlement, improves uniformity of properties through the section and retains strength at elevated temperature.
GB
GB/T 3077 Series
In GB/T 3077 the same Cr-Mo pattern carries higher strength levels as the carbon digit rises: 30CrMo → 35CrMo → 42CrMo. They are not interchangeable without re-checking the required properties.
Reading the name correctly: the two leading digits are rounded from the mean carbon content, not a strength value in ksi or MPa. Nothing in the designation tells you the delivery condition — that has to be agreed separately and stated on the MTC.
04Equivalent & Comparable Grades
Where this grade sits in the major standard systems. "Comparable" means similar alloy design and application, not automatic interchangeability.
Standard System
Grade
Remark
China GB/T 3077
30CrMo
Base grade of this page
Japan JIS G4053
SCM430
Stated as the equivalent grade on this product page
USA ASTM / AISI / SAE
4130
Comparable Cr-Mo alloy steel; check C, Mn and P/S windows before substitution
Europe EN 10083-3
25CrMo41.7218
Comparable Cr-Mo heat-treatable steel
Before substituting: the alloy ranges of these grades overlap but the impurity limits, deoxidation practice, testing requirements and certification differ. Confirm acceptance with the design authority or the end specification before ordering a substitute, then have every mechanical value re-verified against the heat-treatment condition actually supplied.
05Chemical Composition
Cast (heat) analysis of 30CrMo. The source column marks which values come from the data published on this product page and which come from the GB/T 3077 published limits.
Element
Limit (%)
Source
C (Carbon)
0.26 – 0.34
Product data sheet
Si (Silicon)
0.17 – 0.37
Product data sheet
Mn (Manganese)
0.40 – 0.70
Product data sheet
P (Phosphorus)
0.035 max
Product data sheet
S (Sulfur)
0.035 max
Product data sheet
Cr (Chromium)
0.80 – 1.10
GB/T 3077 published limit
Mo (Molybdenum)
0.15 – 0.25
GB/T 3077 published limit
Ni (Nickel)
0.30 max
GB/T 3077 residual limit
Cu (Copper)
0.30 max
GB/T 3077 residual limit
Two things to be aware of: (1) The composition table published with this product lists only C, Si, Mn, P and S under a column headed "The Element Max (%)" — the chromium and molybdenum that define the grade are not printed there. We have published the source data as given and added the missing elements from the GB/T 3077 limits; whatever you order, make sure Cr and Mo appear with their actual values on the MTC. (2) Different published versions give the phosphorus and sulfur ceiling as either 0.030% or 0.035%; this page keeps the 0.035% value used here, so state the ceiling you want when the steel goes into safety-critical or low-temperature service. Product analysis tolerances, and any requirement for a finer analysis, follow the current GB/T 3077 version and the order specification.
06Mechanical Properties
Values published for this product, given per thickness band.
Grade
Thickness t (mm)
Yield ReL (MPa, min)
Tensile Rm (MPa, min)
Hardness HB
30CrMo
6 – 50
785
930
—
30CrMo
50 – 200
785
930
—
Note: The hardness column is empty in the source table, so no hardness value is quoted here. GB/T 3077 additionally publishes — for the standard 25 mm test blank after quenching and tempering — elongation after fracture A ≥ 12%, reduction of area Z ≥ 50%, impact energy AkV ≥ 63 J, and hardness ≤ 229 HB in the annealed or high-temperature tempered delivery condition. Published sources do not fully agree on every one of these figures, and all of them move with section size and heat treatment, so treat them only as a reference frame and write the values you need into the order. Note also that this page supplies 8 – 250 mm thickness while the mechanical bands above cover 6 – 200 mm; above 200 mm, properties must be agreed per enquiry.
07Heat Treatment & Delivery Condition
30CrMo reaches its specified properties through heat treatment, so the treatment cycle belongs in the enquiry, not in the small print.
Item
Published / Practised Value
Quenching
880 °C, water or oil quench
Tempering
540 °C, water or oil cool
Hardenability
Critical diameter in oil approx. 15 – 70 mm
Temper Embrittlement
Avoid tempering in the 300 – 350 °C range
Elevated Temperature
Useful strength retained below about 500 °C
Delivery Condition
As Rolled (AR)AnnealedNormalized (N)High-temperature TemperedQuenched & Tempered (Q+T)
Weldability
Good at the lower end of the alloy range, moderate near the upper limits; preheating (commonly 175 °C and above) is standard practice and must be set from thickness and carbon equivalent
Note: GB/T 3077 leaves the delivery condition to be agreed — heat treated (normalizing, annealing or high-temperature tempering) or untreated — and requires it to be stated in the contract. The quenching and tempering temperatures above are the commonly published reference cycle for this grade; the parameters actually applied to your order are those agreed with the mill and reported on the MTC. Preheat temperature for welding is a procedure decision, validate it against your welding procedure specification.
08Typical Applications
Where quenched and tempered 30CrMo plate is normally consumed.
High-Strength Fasteners
The core application: 8.8S and 10.9S grade high-strength bolts and associated nuts and studs.
Gears, Shafts & Linkages
Transmission gears, shafts, pinions, connecting rods and other parts under combined static and dynamic load.
Oil, Gas & Petrochemical
High-pressure piping and guides, headed plates and tube sheets, hydrogenation and heat-exchange equipment parts.
Power Generation
Boiler and turbine auxiliaries, high-temperature fasteners and structural parts in thermal power units.
Automotive & Engineering
Engine crankshafts, heavy vehicle components and general engineering structures needing strength with toughness.
Selection advice: when the part is a safety-critical fastener or a dynamically loaded component, order to the property requirement rather than to the grade name alone — specify strength class, hardness range, impact requirement (with temperature), UT acceptance level and delivery condition together.
09Processing, Testing & Supply
From mill plate to finished, certified item.
1
Cutting & Machining
Plate cut to length and width or profiled to drawing; machining support arranged for bolt and component makers.
2
Heat Treatment
Annealing, normalizing, high-temperature tempering or full quench and temper to the mechanical targets you specify.
3
Inspection
Chemical analysis, tensile test, hardness and UT carried out per heat; third-party inspection supported on request.
4
Certified Delivery
MTC issued with each heat; packed for export and shipped promptly from stock or within 10 – 40 working days for custom production.
Quote checklist — quote faster if you send: product form (plate / round bar), thickness × width × length, quantity, delivery condition (AR, annealed, normalized, tempered or Q+T), required mechanical values (yield, tensile, elongation, impact with temperature, hardness), UT acceptance level, MTC type, destination port and preferred payment terms. MOQ is 1 PC.
10Frequently Asked Questions
Q1Is 30CrMo the same as ASTM 4130?
They are close chromium-molybdenum grades with overlapping alloy ranges, and in many machined or tubular parts substitution is technically feasible — but it should never be treated as automatic. Compare the carbon, manganese and P/S windows, require the same heat-treatment condition and mechanical values, and re-verify impact and hardness for your service. If the design specification names a grade, that grade must be supplied or a formal deviation approved.
Q2How does 30CrMo differ from 35CrMo and 42CrMo?
Same alloy family, rising carbon level: as it goes from 30 to 35 and 42, attainable strength and hardness rise while ductility and weldability fall. Do not swap them on the drawing — choose according to the strength level the part is designed for. See also our pages for 35CrMo and 42CrMo.
Q3In which condition will my plate be delivered?
Whatever is agreed in the contract. GB/T 3077 permits delivery either heat treated (normalizing, annealing or high-temperature tempering) or untreated, so always write the delivery condition into the enquiry — otherwise quotations from different suppliers will not be comparable.
Q4Can you supply a hardness value and impact energy?
The table published with this product covers yield and tensile only, so nothing further is quoted here. Give us the hardness range and impact requirement (with test temperature) together with the delivery condition, and we will confirm what the heat can meet before you order.
Q5What is the minimum quantity and how fast can you ship?
MOQ is 1 PC. Standard sizes are held available and ship promptly; custom production runs 10 – 40 working days. The published quantity schedule gives 5 days for 1 – 10 t, 10 days for 10 – 50 t and negotiable above 50 t.
Q6What documents come with the material?
A Mill Test Certificate (MTC) reporting heat analysis and test results, with third-party inspection arranged on request. Ask for any extra coverage — UT acceptance level, additional impact testing, or a nominated inspection agency — when you place the enquiry, so it can be built into the order rather than added afterwards.
Send us your product form (plate or round bar), dimensions (thickness × width × length), quantity, delivery condition and required mechanical values. We will reply with stock status, competitive factory price, delivery time and the complete certification package within 24 hours.
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