30CrNi4MoA / EN30B Alloy Steel Bar Supplier | 835M30

Xi'an Dongmeng Group Co., Ltd. is one of the most reliable manufacturers and suppliers of 30CrNi4MoA / EN30B Alloy Steel Bar Supplier | 835M30 in China, also supports customized service. With abundant experience, we warmly welcome you to wholesale cheap products in stock here and get free sample from our factory. For price consultation, contact us.

4% Nickel-Chromium-Molybdenum Steel for High-Strength, Large-Section Components

30CrNi4MoA, commonly compared with EN30B and 835M30, is a high-hardenability nickel-chromium-molybdenum alloy structural steel used for heavily loaded shafts, gears, connecting rods, drilling tools, transmission components and large-section engineering parts.

Its high nickel content supports excellent toughness, while chromium and molybdenum improve hardenability, strength, fatigue resistance and performance through thick sections.

Available supply:

30CrNi4MoA · EN30B · 835M30
Round Bar · Forged Bar · Flat Bar · Block · Shaft Forging
Annealed · Normalized and Tempered · Quenched and Tempered
Black · Peeled · Turned · Rough Machined · Ground
UT Inspection · Mechanical Testing · EN 10204 3.1 MTC
Custom Cutting · Forging · Heat Treatment · Rough Machining

30CrNi4MoA is a medium-carbon, high-nickel chromium-molybdenum alloy steel designed for high-strength components requiring good toughness and deep hardening through large cross-sections.

EN30B is the former BS 970:1955 designation, while 835M30 is the related designation used under BS 970 Part 1:1983. These grades contain approximately 4% nickel and are commonly selected where lower-alloy engineering steels may not provide sufficient through-hardening capability or toughness in large sections.

Unlike conventional low-carbon carburizing grades, EN30B is principally a through-hardening steel. Surface carburizing or other surface-hardening treatments may be considered when additional localized wear resistance is required, but they are not the default material condition.

The grade is particularly suitable for components exposed to:

High static and dynamic loads

Repeated impact

Torsional loading

Fatigue cycles

Large-section heat treatment

High tensile-strength requirements

Dimensional-distortion concerns during hardening

30CrNi4MoA is listed as a high-purity alloy structural steel grade under GJB 6487-2008, while EN30B and 835M30 are associated with the historical BS 970 designation system. Grade substitution must always be approved against the governing drawing, chemical composition, mechanical-property requirements and heat-treatment specification.

The approximately 4% nickel content is one of the defining characteristics of this grade. It contributes to high toughness and supports uniform properties through relatively large cross-sections. Chromium and molybdenum improve hardenability, strength and resistance to tempering effects. 

The following ranges may be used after confirming them with the production and inventory departments.

Mechanical properties must be specified together with the heat-treatment condition and ruling section. The following values are technical references rather than universal guaranteed values. 

Annealing

EN30B can be supplied in the annealed condition to improve machinability before final hardening.

A typical soft-annealing treatment may involve heating to approximately 630–650°C, soaking sufficiently and cooling in the furnace or still air. Repeating the annealing cycle may improve machining characteristics.

Typical annealed hardness should be agreed with the purchaser. Reference limits around 269–277HB are commonly used depending on the applicable supply specification.

Hardening

A typical hardening cycle involves:

Controlled preheating

Austenitizing at approximately 810–840°C

Air cooling, forced-air cooling or oil quenching depending on section size

Immediate tempering after hardening

The quenching method must be selected according to component geometry, ruling section, distortion risk and required mechanical properties.

Tempering

High-strength conditions commonly use tempering in the approximate range of 200–280°C. However, the final tempering temperature must be chosen according to the required combination of strength, hardness and impact toughness.

Tempering cycles must not be copied from a generic data sheet without considering:

Component diameter

Furnace type

Soaking time

Quenching medium

Test position

Required impact properties

Final hardness

Stress Relieving

Stress relieving is recommended after heavy rough machining and before final machining or hardening, particularly for large or complex components where dimensional stability is critical.

Optional Surface Hardening

EN30B may receive localized carburizing or other surface-hardening treatment when additional wear resistance is required. However, it should primarily be presented as a through-hardening Ni-Cr-Mo steel rather than a conventional carburizing grade.

Hot-rolled black surface

Forged black surface

Shot-blasted surface

Peeled bar

Turned bar

Rough-machined forging

Polished bar

Precision-ground bar

Anti-rust oil protection

Dimensional tolerances can be supplied according to:

EN 10060

ASTM A29/A29M

Customer drawing

Machining allowance agreement

Final component tolerance requirements

For forged or rough-machined components, sufficient machining allowance should be agreed before production.

High Through-Hardening Capability

Its high nickel content and Ni-Cr-Mo alloy system allow useful mechanical properties to be developed through relatively large sections.

High Strength with Toughness

The grade can achieve high tensile and yield strength while retaining impact resistance when the heat treatment is correctly selected.

Suitable for Large Forgings

30CrNi4MoA is suitable for large shafts, gear blanks, thick bars and forged components where uniform core properties are required.

Good Fatigue Performance

The material is used for parts exposed to repeated bending, torsion, impact and cyclic mechanical loading.

Reduced Risk of Severe Quench Distortion

Depending on section size and target properties, EN30B may be hardened using air, forced air or oil, helping engineers select an appropriate balance between hardening response and distortion risk.

Machinable in the Annealed Condition

Annealed material can be supplied for rough machining before final heat treatment.

Custom Property Control

Heat treatment can be designed around a required combination of hardness, tensile strength, yield strength, impact energy and dimensional stability.

Deep Carburizing Performance – Ideal for heavy gears and shafts.

High Core Toughness – Nickel enhances impact resistance.

Superior Fatigue Strength – Designed for high-load cyclic conditions.

Excellent Wear Resistance – Durable surface for long-term use.

Stable Heat Treatment Performance – Uniform properties in thick sections.

30CrNi4MoA / EN30B is suitable for heavily loaded engineering components, including:

Power Transmission

Heavy-duty gears

Pinions

Differential shafts

Transmission shafts

Gearbox components

Couplings

Splined shafts

Aerospace and High-Strength Engineering

Connecting rods

Airframe forgings

High-load structural connectors

Large-section fastener components

Critical shafts

Landing-gear-related parts where technically approved

Oil, Gas and Mining Equipment

Downhole tools

Rock-drilling tool bodies

High-load drilling components

Heavy rollers

Mining-machine shafts

Impact-loaded tool holders

Die, Mould and Press Equipment

Plastic mould blocks

Injection mould components

Compression moulds

Punch holders

Rams

Anvils

Header dies and rings

Heavy Machinery

Large axles

Drive shafts

Crane transmission parts

Forged machine components

High-load bearing components

Rolling and forming equipment parts

EN30B is widely used where high tensile strength, toughness and through-hardening capability are required in complex or large-section components.

Every heat can be traceable from raw material to finished product through heat number, production records and inspection documentation.

Raw Material and Chemical Control

Optical emission spectroscopy

Ladle analysis verification

Product analysis when required

Heat-number traceability

Alloy-element verification

Mechanical Testing

Tensile strength

Yield or proof strength

Elongation

Reduction of area

Charpy impact testing

Brinell or Rockwell hardness

Test position according to section size

Non-Destructive Testing

Ultrasonic testing

Magnetic-particle testing

Surface visual inspection

Straightness inspection

Dimensional measurement

The required UT standard and acceptance class should be stated in the inquiry rather than using only the description "UT passed."

Metallurgical Inspection

Grain-size examination

Microstructure examination

Decarburization inspection

Inclusion cleanliness

Macro-etch testing

Hardenability assessment

Case-depth testing when surface hardened

Documents Available by Agreement

EN 10204 3.1 material certificate

EN 10204 3.2 inspection certificate

Heat-treatment record

UT report

Mechanical-test report

Chemical-analysis report

Dimensional inspection report

Third-party inspection by SGS, BV or TÜV

The existing page already promotes EN 10204 3.1/3.2 and third-party inspection; these claims should remain only where they can be supported by actual documentation.

Machining

For efficient rough machining, annealed or softened material is generally recommended.

Available processing can include:

Saw cutting

Center drilling

Turning

Peeling

Boring

Milling

Rough machining

Precision grinding

Machining allowance preparation

The purchaser should indicate whether dimensions are required before or after heat treatment.

Welding

Because of the alloy content, hardenability and carbon level, welding should be treated as a controlled special process.

Where welding is unavoidable, the welding procedure should define:

Preheating temperature

Interpass-temperature control

Low-hydrogen consumables

Cooling rate

Post-weld heat treatment

Hardness control

NDT requirements

Welding should not be performed on critical EN30B components without an approved welding procedure and engineering evaluation.

Forging

Large-section forgings require controlled heating, adequate soaking and slow cooling after forging. Forging temperature, reduction ratio and post-forging heat treatment should be established according to the billet size and final component requirements.

30CrNi4MoA / EN30B bars and forgings are packed according to product size, surface condition and transportation method.

Standard Export Packing

Steel-strapped bundles

Anti-rust oil

Waterproof wrapping

Wooden skids

Wooden cases for machined parts

Protective end covers

Lifting points for heavy forgings

Heat-number tags

Shipping marks

Packing list identification

Container and Break-Bulk Shipment

20-foot container loading

40-foot container loading

Open-top container for oversize forgings

Flat-rack loading

Break-bulk vessel shipment

Reinforced blocking and lashing

Machined surfaces can be protected with rust-preventive oil, VCI material and moisture-resistant wrapping.

Choose Annealed Material When:

Extensive machining is required

The customer will conduct final heat treatment

Low delivery hardness is preferred

Complex machining is required before hardening

Choose Quenched and Tempered Material When:

Final mechanical properties are required before delivery

The component will receive limited further machining

Strength and hardness must be verified on the MTC

The customer requires a defined tensile-strength range

Choose Rough-Machined Forgings When:

The component is large

Internal soundness must be checked after forging

Machining allowances must be controlled

UT inspection is required on a defined surface condition

The final component is a shaft, ring, block or gear blank

Choose a Case-Hardening Grade Instead When:

A precisely controlled deep carburized case is the primary requirement

The design requires a lower-carbon, softer core

The drawing specifically requires a traditional carburizing-steel grade

EN30B should be selected primarily for high-strength through-hardening applications rather than solely because a hard surface is required.

Technical Grade Verification

We review the requested grade, standard, chemical composition and mechanical-property condition before quotation.

Bars and Custom Forgings

Supply options cover standard bars as well as shafts, blocks, gear blanks, rings and drawing-based forgings.

Heat-Treatment Coordination

Annealing, normalizing, quenching, tempering and stress relieving can be arranged according to the required final properties.

Inspection Before Shipment

Chemical analysis, mechanical tests, hardness measurement, UT inspection and dimensional reports can be provided according to the purchase specification.

Custom Processing

Saw cutting, peeling, turning, boring, rough machining and machining-allowance preparation are available.

Export Documentation

Materials can be supplied with heat-number traceability, packing lists, test reports, inspection documents and seaworthy export packing.

Please provide:

Required grade and standard

Product form

Diameter, thickness or drawing dimensions

Length

Quantity or unit weight

Delivery condition

Required hardness or tensile strength

Impact-test temperature and minimum energy

UT standard and acceptance class

Surface condition

Machining requirements

Required certificate type

Destination port

Required delivery date

Is 30CrNi4MoA the Same as EN30B?

Their typical chemical-composition ranges are closely comparable, particularly the approximately 4% nickel, 1.1–1.4% chromium and 0.20–0.35% molybdenum contents.

However, 30CrNi4MoA and EN30B belong to different standard systems. Final substitution must be confirmed against the governing specification, MTC and required mechanical properties.

Is EN30B a Carburizing Steel?

EN30B is primarily a through-hardening Ni-Cr-Mo engineering steel.

It may receive optional surface carburizing or surface-hardening treatment when extra wear resistance is required, but it should not be described simply as a low-carbon carburizing steel.

What Is the Nickel Content of EN30B?

The typical nickel range is approximately 3.90–4.30%, making it a high-nickel alloy engineering steel.

What Is the Difference Between EN30B and 835M30?

EN30B is the former designation under BS 970:1955. The corresponding later British designation is commonly written as 835M30 under BS 970 Part 1:1983.

Can EN30B Be Supplied Quenched and Tempered?

Yes. It can be supplied annealed or quenched and tempered according to the required hardness, tensile strength and section size.

The required mechanical-property range should be stated in the purchase order.

Can You Supply Large-Diameter Forged Bars?

Large forged bars, shafts, blocks, rings and gear blanks can be supplied according to the required dimensions and drawing.

Production feasibility depends on unit weight, forging ratio, heat-treatment capacity and UT requirements.

What Mechanical Properties Should Be Specified?

The inquiry should define tensile strength, yield or proof strength, elongation, impact energy, hardness, test temperature and ruling section.

A generic grade name alone is not sufficient for a critical component.

Is Ultrasonic Testing Available?

Yes. UT can be arranged, but the inquiry should state the required testing standard, scanning surface, test stage and acceptance level.

Is EN 10204 3.1 Certification Available?

EN 10204 3.1 certification can be supplied when specified in the order. Third-party witnessing or EN 10204 3.2 documentation may also be arranged by agreement.

Can EN30B Be Welded?

Welding is possible only with carefully controlled procedures. Preheating, low-hydrogen consumables, controlled cooling and post-weld heat treatment may be required.

For critical components, welding should be approved by the design engineer.

Request a Technical Quotation for 30CrNi4MoA / EN30B Alloy Steel

Send us your material standard, dimensions, quantity, heat-treatment condition, mechanical-property requirements and inspection level.

We will review:

Grade compatibility

Available production route

Heat-treatment condition

Machining allowance

UT requirements

Mechanical-property feasibility

Packing and shipment method

Xi'an Dongmeng Group Co., Ltd.

Email: office@dongmjd.com
WhatsApp: +86 157 6921 4734

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