Material 28Mn6 1.1170 Structural Steel

Product Overview

28Mn6 / 1.1170 is a widely used quality carbon-manganese steel compliant with the European standards EN 10083-2(Non-alloy steels for quenching and tempering) and EN 10250-2(Open die steel forgings for general engineering purposes). With a carbon content of 0.25–0.32% and approximately 1.30–1.65% manganese, this medium-carbon manganese steel provides excellent strength, toughness, and wear resistance after normalizing or quenching and tempering heat treatment.

GB 30Mn2, JIS SMn433, and ASTM 1330/1527 are all medium-carbon manganese quenched and tempered structural steels, offering excellent comprehensive mechanical properties and good processability. GB 30Mn2 is a grade specified in the Chinese National Standard (GB/T 3077), classified as a high-quality alloy structural steel. With a carbon content of approximately 0.27%-0.34% and a relatively high manganese content (1.40%-1.80%), it exhibits good hardenability, strength, and wear resistance. Typically used after quenching and tempering (high-temperature tempering), it achieves a favorable balance of strength and toughness, making it suitable for manufacturing shafts, connecting rods, bolts, and other mechanical components subjected to high loads.

JIS SMn433 is an alloy structural steel grade under the Japanese Industrial Standard (JIS G4053). Its chemical composition and mechanical properties are highly similar to GB 30Mn2. It also uses manganese as the primary alloying element, designed to achieve high strength and good toughness through quenching and tempering. Within the Japanese industrial system, this steel is commonly used for transmission components in automobiles and general machinery, as well as high-strength fasteners, demonstrating excellent machinability and reliability.

ASTM A1330 (bars) and ASTM A1527 (forgings) are medium-carbon manganese steel grades under the American Society for Testing and Materials standards. Their chemical composition ranges largely correspond to the aforementioned grades, with carbon content approximately 0.22%-0.29% and manganese content 1.20%-1.50%. Through appropriate quenching and tempering, this material achieves high yield strength and tensile strength while maintaining sufficient impact toughness. It is suitable for manufacturing critical load-bearing components such as gears, axles, and crankshafts.

Equivalent Grades Across Countries

28Mn6 (1.1170) has direct equivalents in major global steel standards, ensuring compatibility with international manufacturing processes. Here’s how it maps to other grades:

Country	China	Japan	Europe	USA
Standard	GB/T 3077	JIS G4053	EN10250-2	ASTM A29
Grade	30Mn2	SMn433	28Mn6/1.1170	1330/1527

This cross-standard compatibility makes 28Mn6 a flexible choice for global supply chains and multi-region manufacturing projects.

Product Features

Chemical Composition of 28Mn6 (1.1170)

The balanced chemical makeup of 28Mn6 is what drives its superior performance. Strictly controlled impurities ensure durability and consistency:

Grade	C	Si	Mn	P	S	Cr
30Mn2	0.27-0.34	0.17-0.37	1.40-1.80	0.030Max	0.030Max	/
SMn433	0.30-0.36	0.15-0.35	1.20-1.50	0.030Max	0.030Max	0.35Max
28Mn6/1.1170	0.25-0.32	0.40Max	1.30-1.65	0.030Max	0.035Max	0.40Max
1330/1527	0.22-0.29	0.40Max	1.20-1.50	0.040Max	0.050Max	/

The high manganese content (1.30–1.65%) enhances hardenability and strength, while low phosphorus and sulfur levels minimize brittleness and improve weldability (when proper processes are followed).

Mechanical Properties of 28Mn6 (1.1170)

Mechanical performance varies by heat treatment and component size. Below are the key properties as per EN 10083-2 and EN 10250-2 standards:

1. Quenching and Tempering (QT) Properties

Ideal for high-strength applications, QT-treated 28Mn6 delivers excellent tensile strength and yield strength:

Size range(d/t)	Tensile strength	Yield strength	Alongation	Area of reduction	Impact value At RT/J
d≤16 t≤8	800-950Mpa	590Mpa Min	13% Min	40% Min	/
16＜d≤40 8＜t≤20	700-850Mpa	490Mpa Min	15% Min	45% Min	40J Min
40＜d≤100 20＜t≤60	650-800Mpa	440Mpa Min	16% Min	50% Min	40J Min

2. Normalizing Properties

Suitable for general engineering parts, normalized 28Mn6 offers balanced strength and ductility:

Size range(d/t)	Tensile strength	Yield strength	Alongation
d≤16 t≤16	630Mpa	345Mpa Min	17% Min
16＜d≤100 16＜t≤100	600Mpa	310Mpa Min	18% Min
100＜d≤250 100＜t≤250	590Mpa	290Mpa Min	18% Min

3. Open Die Forgings (Normalized / Normalized + Tempered)

For forged components, properties adhere to EN 10250-2:

Size range	Tensile strength	Yield strength	Alongation		Impact value at RT/J
			L	Tr	L	Tr
d≤100	600Mpa Min	310Mpa Min	18% Min	/	35J Min	/
100＜d≤250	570Mpa Min	290Mpa Min	18% Min	12% Min	30J Min	20J Min
250＜d≤500	540Mpa Min	270Mpa Min	18% Min	12% Min	25J Min	15J Min
500＜d≤1000	540Mpa Min	260Mpa Min	17% Min	11% Min	20J Min	15J Min

Remark: L= Longitudinal    Tr = Transverse

Surface Hardness & Hardenability

28Mn6 hardness is customizable via heat treatment, making it adaptable to diverse applications:

Hardness by Heat Treatment

Heat Treatment	Hardness
Treated to improve shearability (+S)	HB255Max
Soft annealed (+A)	HB223Max
Quenched and tempred (+QT)	HRC28-32(Common Range)

Hardenability (End Quench Test)

For applications requiring controlled hardening depth, 28Mn6 offers three hardenability grades (+H, +HH, +HL):

Distance in mm from quenched end
Distance		1	2	3	4	5	6	7	8	9	10	11	13	15	20	25	30
Hardness In HRC + H	max	54	53	51	48	44	41	38	35	31	29	27	26	25	25	24	/
	min	45	42	37	27	21	/	/	/	/	/	/	/	/	/	/	/

Distance in mm from quenched end
Distance		1.5	3	5	7	9	11	13	15	20	25	30	35	40	45	5
Hardness In HRC + HH	max	54	53	51	48	44	41	38	35	31	29	27	26	25	25	24
	min	48	46	42	34	30	27	24	21	/	/	/	/	/	/	/
Hardness In HRC + HL	max	51	49	46	41	35	32	29	26	22	20	/	/	/	/	/
	min	45	42	37	27	21	/	/	/	/	/	/	/	/	/	/

Scatter bands for the Rockwell - C hardness in the end quench hardenability test.

Supply Sizes, Tolerances & Surface Finishes

We offer 28Mn6 in a wide range of forms to suit your manufacturing needs, with strict quality control for dimensions and surface quality:

1. Supply Sizes

Product type	Size range	Length
Cold drawn bar	Φ3-Φ80mm	6000-9000mm
Hot rolled bar	Φ16-Φ310mm	6000-9000mm
Hot forged bar	Φ100-Φ1200mm	3000-5800mm
Hot rolled plate/sheet	T:3-200mm; W:1500-2500mm	2000-5800mm
Hot Forged block	T: 80-800mm; W: 100-2500mm	2000-5800mm

2. Stock Sizes (Hot Rolled & Forged Bars)

• Hot Rolled Bar Stock Diameters: 16, 18, 20, 22, 24, 25, 26, 27, 28, 30, 31, 32, 33, 35, 36, 38, 39, 40, 42, 45, 46, 48, 50, 52, 55, 56, 58, 60, 62, 63, 65, 68, 70, 72, 75, 78, 80, 82, 83, 85, 87, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260mm.

  
  

• Hot Forged Bar Stock Diameters: 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530mm.

Stock availability changes daily—contact our sales team for real-time inventory updates.

3. Tolerances & Straightness

Surface Finish	Turned	Milled	Grinding(Best)	Polished(Best)	Peeled(Best)	Black Forged	Black Rolled
Tolerance	+0/+3mm	+0/+3mm	+0/+0.05mm	+0/+0.05mm	+0/+0.1mm	+0/+5mm	+0/+1mm
Straighness	1mm/1000mm max.					3mm/1000mm max.

Forging & Heat Treatment Processes

Proper processing is critical to unlocking 28Mn6 performance. Here are the recommended procedures:

1. Forging Processing

• Heat 28Mn6 ingot to 1150–1200℃

• Forge at a minimum temperature of 850℃

• Cooling in the air after forged

2. Heat Treatment

• Soft Annealing: Heat to 820–850℃ → Soak → Furnace cool. Ideal for improving machinability

• Normalizing: Heat to 850–880℃ → Soak → Air cool. Enhances strength and ductility for general use

• Quenching & Tempering (QT): Heat to 840–880℃ → Soak → Quench in water (lower temp range) or oil (upper temp range) → Temper at 540–680℃ → Air cool. Delivers maximum strength and toughness

Note: Temperatures are guidelines—adjust based on component size and application requirements.

Weldability of 28Mn6 (1.1170)

28Mn6 has moderate weldability due to its medium carbon and high manganese content, which increases hardenability. To avoid cold cracking in the heat-affected zone (HAZ), follow these critical steps:

• Preheating: Heat the base material to reduce cooling rates (recommended temperature: 150–250℃).

• Low-Hydrogen Materials: Use low-hydrogen electrodes or filler metals to minimize hydrogen-induced cracking.

• Post-Weld Heat Treatment: Perform stress relief annealing to soften the HAZ and reduce residual stresses.

Improper welding can compromise joint integrity—consult our technical team for custom welding guidelines.

Applications of 28Mn6 (1.1170) Steel

28Mn6 versatile properties make it a staple in multiple industries. Key applications include:

1. Machinery Manufacturing & General Engineering

• Shaft components: Drive shafts, spindles, mandrels (for moderate loads and rotational speeds)

• Fasteners: High-strength bolts, studs, nuts

• Structural parts: Gears, sprockets, connecting rods, worms (require strength and wear resistance)

2. Automotive Industry

• Steering knuckles, connecting rods, splined shafts

• Transmission gears and secondary shafts (QT-treated to meet strength/durability requirements)

3. Tools & Molds

Fixtures, chucks, mold bases (for applications not subjected to severe impact)

28Mn6 (1.1170) vs Other Structural Steel Grades: Detailed Head-to-Head Comparison

To help global customers make accurate material selection decisions, we’ve compiled a full comparative analysis of 28Mn6 (1.1170) against the most commonly confused and substituted structural steel grades, covering composition, mechanical properties, processability, cost and application scenarios.

Comparison Table: 28Mn6 vs Competing Grades

In-Depth Grade-by-Grade Difference Explanation

1. 28Mn6 (1.1170) vs 30Mn2

These two grades are often considered interchangeable, but critical differences make them suitable for distinct scenarios. 30Mn2 has a 0.05-0.15% higher manganese content and slightly higher carbon, which boosts its hardenability and ultimate tensile strength, making it better suited for large-section forgings and heavy-load shafts in Chinese standard projects. 28Mn6 stands out with a controlled chromium allowance and tighter impurity limits, delivering more consistent mechanical properties across different heat treatment batches, and better adaptability to European and international processing standards. 28Mn6 also has marginally better ductility, reducing the risk of cracking during cold bending and light forming. For cross-border projects requiring compliance with EN standards, 28Mn6 is the preferred choice over 30Mn2.

2. 28Mn6 (1.1170) vs C45 (1.0503)

C45 is a high-carbon steel with nearly double the manganese content of 28Mn6, focusing on ultra-high strength and hardness after quenching, but sacrificing ductility and weldability heavily. C45 is prone to cold cracking during welding and has poor impact toughness, only suitable for non-welded, high-wear parts like gears and tool holders. 28Mn6 is the balanced alternative: it offers enough strength for medium-load applications, retains good ductility and impact resistance, and has far better weldability with basic preheat treatment. 28Mn6 is ideal for parts that need both strength and toughness, while C45 is only for high-hardness, low-toughness components. Additionally, 28Mn6 has lower machining tool wear than C45 in soft annealed state, cutting processing costs for mass production.

3. 28Mn6 (1.1170) vs 25Mn

25Mn is a lower-grade, budget-friendly structural steel with lower carbon and manganese content, offering excellent weldability and ductility but significantly lower strength and wear resistance. It is only suitable for light-load, non-critical components like brackets, simple fasteners and general structural parts. 28Mn6 is a step up in performance, with higher strength and hardenability, making it fit for medium-load critical parts such as transmission shafts, connecting rods and forged gear blanks. 25Mn cannot match 28Mn6’s load-bearing capacity and heat treatment potential, so 28Mn6 is the upgrade choice when 25Mn lacks sufficient strength, without jumping to the higher cost of high-alloy steels.

4. 28Mn6 (1.1170) vs SMn433

SMn433 is the Japanese equivalent of 28Mn6, with minor compositional tweaks for Japanese manufacturing processes. SMn433 has tighter silicon control and a narrow carbon range, optimized for precision machining and high surface finish, commonly used in Japanese automotive precision components. 28Mn6 has a more flexible composition range and chromium allowance, making it more versatile for general engineering, open die forgings and cross-regional projects. 28Mn6 also has better hardenability consistency for medium-to-large section parts, while SMn433 is tailored for small-to-medium precision parts. For projects not limited to JIS standards, 28Mn6 offers wider processing compatibility and lower procurement costs.

FAQ

Q1: What is the maximum cross-section size for effective QT treatment of 28Mn6?

A1: For optimal QT performance (tensile strength ≥650MPa), the recommended maximum cross-section size is d/t ≤100mm. For larger sections (100＜d≤200mm), oil quenching + high-temperature tempering is required, with a slight reduction in ultimate strength but maintained toughness.

Q2: Is 28Mn6 suitable for surface hardening (carburizing/nitriding)?

A2: 28Mn6 is suitable for nitriding (after QT treatment) to enhance surface hardness (HV 500-600) and wear resistance—ideal for gears and shafts. Carburizing is not recommended due to its medium carbon content (0.25-0.32%), which can lead to excessive surface hardness and brittleness.

Q3: Can ASTM 1330 be directly replaced with 28Mn6 in American manufacturing projects?

A3: Yes—ASTM 1330 is the direct American equivalent of 28Mn6, with minor compositional differences (lower C/Mn in 1330). 28Mn6 can replace ASTM 1330 for all applications with a slight adjustment to heat treatment temperatures (increase quenching temperature by 10-20℃ for 28Mn6 to match 1330’s performance).

Q4: What is the shelf life and storage requirement for 28Mn6 steel?

A4: 28Mn6 has an unlimited shelf life when stored in a dry, well-ventilated environment (relative humidity ≤60%). Black surface steel should be coated with anti-rust oil; precision finished (ground/polished) steel should be sealed in anti-rust film to avoid oxidation.

Inquire Now to get started—we deliver reliable 28Mn6 steel solutions worldwide.