Case-hardening steels are employed for the fabrication of mechanical parts that have to be hardened through heat treatments of carboncementation, carbonitriding, followed by quenching and tempering, so that you can obtain a hard surface, characterized by toughness and resistance at heart.
Not only an excellent resistance at heart, but also a high mechanical wear resistance is obtained.
To obtain elevated toughness, steels with a high percentage of nickel will be preferred.
Case-hardening steels are employed to build gears, shafts, linchpins, mechanical parts for the adaptors sector, industrial, automotive and mechanical parts in general.
The eligibility of the case-hardening treatment depends on the steel's quality, on the austenitic grain size that is formed during the treatment and on the percentage of carbon and alloy elements, which change for each quality.
Case-hardening steels
Case-hardening steels are employed for the fabrication of mechanical parts that have to be hardened through heat treatments of carboncementation, carbonitriding, followed by quenching and tempering, so that you can obtain a hard surface, characterized by toughness and resistance at heart.
CASE-HARDENING STEELS (EN 10084)
| QUALITY | SURFACE CONDITION | Ø DIAMETER (mm) |
|---|---|---|
| 16MnCr5 (+A) Machinable Annealed | rolled drawn / peeled h11 |
20-210 18-80 |
| 16MnCr5 (+A) Machinable Annealed High Machinability | rolled peeled h11 |
20-80 19-78 |
| 20MnCr5 (+A) Machinable Annealed | rolled forged turned drawn / peeled h11 |
20-300 310-500 16-80 |
| 20MnCrS5 (+I) Isothermal Annealed | rolled | 40-170 |
| 20MnCr5 (+A) Machinable Annealed High Machinability | rolled peeled h11 |
20-80 19-78 |
| 16NiCr4 Machinable Annealed | rolled drawn / peeled h11 |
20-260 16-80 |
| 16NiCr4 (+A) Machinable Annealed High Machinability | rolled peeled h11 |
20-80 19-78 |
| 16NiCr4+Pb (+A) Machinable Annealed | rolled drawn / peeled h11 |
24-160 5-100 |
| 17NiCrMoS6-4 (+A) Machinable Anneled | rolled forged turned drawn / peeled h11 |
20-320 330-1200 20-80 |
| 17NiCrMoS6-4 +I (Isothermal Annealed) | rolled | 90-170 |
| 17NiCrMoS6-4 (+A) Machinable Annealed High Machinability | rolled peeled h11 |
20-80 19-78 |
| 17NiCrMoS6-4+Pb (+A) Machinable Annealed | rolled drawn / peeled h11 |
20-200 5-100 |
| 16NiCrMo12 (+A) Annealed | rolled | 20-250 |
| 18CrNiMo7-6 (+A) Machinable Annealed | rolled reeled forged turned |
40-220 230-490 |
| ZF1A (18CrNiMo7-6~) Annealed | rolled reeled forged turned |
40-220 230-490 |
Not only an excellent resistance at heart, but also a high mechanical wear resistance is obtained.
To obtain elevated toughness, steels with a high percentage of nickel will be preferred.
Case-hardening steels are employed to build gears, shafts, linchpins, mechanical parts for the adaptors sector, industrial, automotive and mechanical parts in general.
The eligibility of the case-hardening treatment depends on the steel's quality, on the austenitic grain size that is formed during the treatment and on the percentage of carbon and alloy elements, which change for each quality.
18CrNiMo7-6 (1.6587)
ISO 683-3 / UNI 7846
Annealed (+A)
PROPERTIES AND APPLICATIONS
The characteristics of 18CrNiMo7-6 steel are:
High Hardenability and Hardening Depth: Thanks to its significant chromium, nickel, and molybdenum content, 18CrNiMo7-6 steel exhibits excellent hardenability, allowing for deep and uniform hardening even in large components. This property is crucial for ensuring consistent mechanical properties across significant sections, a critical requirement for parts subjected to complex stresses.
Exceptional Wear and Fatigue Resistance: The combination of an extremely hard surface (obtained after carburizing and quenching) and a tough core gives this steel superior wear resistance and good fatigue strength. These properties are essential for components subjected to repeated loading cycles, intense friction, and abrasion.
Optimal Combination of High Surface Hardness and Core Toughness: This is the distinctive characteristic and primary advantage of carburizing steels. The surface, carbon-enriched during carburizing and subsequently hardened, achieves high hardness values (58-62 HRC) to resist wear and surface deformation, while the core remains tough and impact-resistant.
Good Machinability: Despite its inherent strength and metallurgical complexity, 18CrNiMo7-6 steel is considered relatively easy to machine in its annealed state, which facilitates production processes.
18CrNiMo7-6 steel is inherently designed to have a "dual nature": an extremely hard surface and a tough core. Its mechanical properties vary drastically between the as-supplied condition (e.g., annealed, <229 HBW) and the final condition after carburizing and quenching (surface 58-62 HRC). This is not a limitation but an inherent characteristic achieved through a specific and controlled heat treatment process. This "dual nature" implies that the component's final performance critically depends on the correct execution of each stage of the heat treatments.
Applications of 18CrNiMo7-6 steel are concentrated in high-stress sectors, including: Automotive / Aerospace / Energy / Heavy Machinery / Naval Industry / Oil Industry.
Typical components made from this steel include: gears, drive shafts and axles, gear shafts, spindles and axles, where high strength and durability are required in demanding rotational applications, wear pins, pinions, wire guides, valve stems, cam parts, and clutch components.
CORRESPONDENCE TO INTERNATIONAL DESIGNATIONS
| QUALITY | EUROPE | GERMANY | FRANCE | SPAIN | G.B. | USA | |
|---|---|---|---|---|---|---|---|
| EN | DIN | W.n. | AFNOR | UNE | B.S. | AISI/SAE | |
| 18CrNiMo7-6 | 18CrNiMo7-6 | 17CrNiMo6 | 1.6587 | 18CND6 | 820A16, ~822M17 | ~4815, ~4820 | |
CHEMICAL COMPOSITION % (EN 10084)
| STEEL DESIGNATION | CHEMICAL COMPOSITION | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| SYMBOLIC | NUMERIC | C | Si max | Mn | P max | S max | Cr | Mo | Ni | B |
| 18CrNiMo7-6 | 1.6587 | 0,15 ÷ 0,21 | 0,40 | 0,50 ÷ 0,90 | 0,035 | 0,035 | 1,50 ÷ 1,80 | 0,25 ÷ 0,35 | 1,40 ÷ 1,70 | - |
CONCENTRATION LIMITS OF THE ELEMENTS THAT ARE NOT INDICATED IN THE TABLE CAN BE DEDUCED IN THE EN 10020 REGULATION. IT CAN BE PROVIDED WITH AN ADDITION OF LEAD 0,12-0,35% OR SULPHUR CONTROLLED UP UNTIL 0,40% FOR AN IMPROVED MACHINABILITY.
JOMINY HARDENABILITY (EN 10084)
| STEEL DESIGNATION | RANGE LIMITS | HRC HARDNESS MEASURED FROM THE QUENCHED END OF THE TEST TUBE (MM) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SYMBOLIC | NUMERIC | 1,5 | 3 | 5 | 7 | 9 | 11 | 13 | 15 | 20 | 25 | 30 | 35 | 40 | |
| 18CrNiMo7-6+H | 1.6587 | max | 48 | 48 | 48 | 48 | 47 | 47 | 46 | 46 | 44 |
43 |
42 | 41 | 41 |
| min | 40 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 32 | 31 | 30 | 29 | 29 | ||
USUALLY AVAILABLE EX STOCK
| M.T. COLORATION | QUALITY | HEAT TREATMENT | SURFACE | DIAMETER(mm) |
|---|---|---|---|---|
 |
18CrNiMo7-6 | Soft-annealed (+A) | rolled forged turned |
30-300 310-520 |
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CORRESPONDENCE TO INTERNATIONAL DESIGNATIONS
| QUALITY | EUROPE | GERMANY | FRANCE | SPAIN | G.B. | USA | |
|---|---|---|---|---|---|---|---|
| EN | DIN | W.n. | AFNOR | UNE | B.S. | AISI/SAE | |
| ZF7B | 16MnCr5+Boro | ||||||
CHEMICAL COMPOSITION % (EN 10084)
| STEEL DESIGNATION | CHEMICAL COMPOSITION | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| SYMBOLIC | NUMERIC | C |
Si max |
Mn |
P max |
S | Cr | Mo | Ni | B |
| ZF7B | CAP.ZF | 0,15 ÷ 0,20 | 0,40 | 1,10 ÷ 1,40 | 0,025 | 0,02 ÷ 0,035 | 1,00 ÷ 1,30 | 0,001 ÷ 0,003 | ||
CONCENTRATION LIMITS OF THE ELEMENTS THAT ARE NOT INDICATED IN THE TABLE CAN BE DEDUCED IN THE EN 10020 REGULATION.
JOMINY HARDENABILITY (ZF)
| STEEL DESIGNATION | RANGE LIMITS | HRC HARDNESS MEASURED FROM THE QUENCHED END OF THE TEST TUBE (MM) | |||
|---|---|---|---|---|---|
| SYMBOLIC | NUMERIC | 5 | 10 | 25 | |
| ZF7B | CAP.ZF | max | 39 | 35 | 27 |
| min | 43 | 39 | 31 | ||
USUALLY AVAILABLE EX STOCK
| M.T. | QUALITY | HEAT TREATMENT | SURFACE | DIAMETER (mm) |
|---|---|---|---|---|
 |
ZF7B (20MnCrB5) | Soft-annealed | rolled reeled | 115-180 |
 |
Download technical sheet |
CORRESPONDENCE TO INTERNATIONAL DESIGNATIONS
| QUALITY | EUROPE | GERMANY | FRANCE | SPAIN | G.B. | USA | |
|---|---|---|---|---|---|---|---|
| EN | DIN | W.n. | AFNOR | UNE | B.S. | AISI/SAE | |
| ZF 1A | 18CrNiMo7-6 | 17CrNiMo6 | 1.6587 | ||||
CHEMICAL COMPOSITION % (EN 10084)
| STEEL DESIGNATION | CHEMICAL COMPOSITION | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| SYMBOLIC | NUMERIC | C | Si max | Mn | P max | S | Cr | Mo | Ni | B |
| ZF 1A | CAP.ZF | 0,15 ÷ 0,21 | 0,40 | 0,50 ÷ 0,90 | 0,025 | ≤ 0,035 | 1,50 ÷ 1,80 | 0,25 ÷ 0,35 | 1,40 ÷ 1,70 | - |
CONCENTRATION LIMITS OF THE ELEMENTS THAT ARE NOT INDICATED IN THE TABLE CAN BE DEDUCED IN THE EN 10020 REGULATION.
JOMINY HARDENABILITY (EN 10084)
| STEEL DESIGNATION | RANGE LIMITS | HRC HARDNESS MEASURED FROM THE QUENCHED END OF THE TEST TUBE (MM) | ||||
|---|---|---|---|---|---|---|
| SYMBOLIC | NUMERIC | 5 | 10 | 25 | 50 | |
| ZF 1A | CAP.ZF | max | 46 | 43 | 39 | 35 |
| min | 42 | 39 | 34 | 30 | ||
USUALLY AVAILABLE EX STOCK
| M.T. COLORATION | QUALITY | HEAT TREATMENT | SURFACE | DIAMETER (mm) |
|---|---|---|---|---|
|
ZF1A (~18CrNiMo7-6) | Annealed (+A) | rolled forged turned |
40-220 230-490 |
|
Download technical sheet |
16MnCrS5/16MnCr5 (1.7139/1.7131)
EN 10084 / ISO 683-3 / UNI 7846
Annealed (+A)
PROPERTIES AND EMPLOYEMENTS
Generally supplied in the annealed state, it guarantees well-defined hardness ranges, facilitating homogeneous and constant machinability. The case-hardening heat treatment allows to increase the surface hardness and thus improve the wear resistance of the surface, maintaining a tough core, capable of absorbing stresses without the risk of brittleness. For applications that require optimized machining, the 16MnCrS5 variant is available, enriched with Sulphur to improve machinability. In some cases, both versions can be supplied with double 16MnCr(S)5 certification. Thanks to its characteristics, 16MnCrS5 represents a strategic choice in the automotive sector and in precision mechanics, where high mechanical performance combined with good machinability are required.
CORRESPONDENCE TO INTERNATIONAL DESIGNATIONS
| QUALITY | EUROPE | GERMANY | FRANCE | SPAIN | G.B. | USA | |
|---|---|---|---|---|---|---|---|
| EN | DIN | W.n. | AFNOR | UNE | B.S. | AISI/SAE | |
| 16MnCr5 | 16MnCr5 | 16MnCr5 | 1.7131 | 16MC5 | 5155 | ||
CHEMICAL COMPOSITION % (EN 10084)
| STEEL DESIGNATION | CHEMICAL COMPOSITION | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| SYMBOLIC | NUMERIC | C | Si max | Mn | P max | S | Cr | Mo | Ni | B |
| 16MnCr5 | 1.7131 | 0,14 ÷ 0,19 | 0,40 | 1,00 ÷ 1,30 | 0,025 | ≤ 0,035 | 0,80 ÷ 1,10 | - | - | - |
| 16MnCrS5 | 1.7139 | 0,020 ÷ 0,040 | ||||||||
CONCENTRATION LIMITS OF THE ELEMENTS THAT ARE NOT INDICATED IN THE TABLE CAN BE DEDUCED IN THE EN 10020 REGULATION.
MECHANICAL CHARACTERISTICS (UNI 7846)
| steel grade | BAR'S DIAMETER | TENSILE TESTING | impact test KCU min | ||||
|---|---|---|---|---|---|---|---|
| Ultimate tensile strength (UTS) R | Yield tensile strength (YTS) Rp 0,2 min | elongation A min | |||||
| mm | N/mm2 | kgf/mm2 | N/mm2 | kgf/mm2 | % | J | |
| 16MnCr5 | 11 (30) (63) |
1030÷1370 (740÷1030) (640÷930) |
105÷140 (75÷105) (65÷95) |
735 (490) (440) |
75 (50) (45) |
8 (9) (10) |
25 (25) (25) |
JOMINY HARDENABILITY (EN 10084)
| steel grade | RANGE LIMITS | HRC HARDNESS MEASURED FROM THE QUENCHED END OF THE TEST TUBE (MM) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| DESIGNATION | Werl.no. | 1,5 | 3 | 5 | 7 | 9 | 11 | 13 | 15 | 20 | 25 | 30 | 35 | 40 | |
|
16MnCr5+H 16MnCrS5+H |
1.7131+H 1.7139+H |
max | 47 | 46 | 44 | 41 | 39 | 37 | 35 | 33 | 31 | 30 | 29 | 28 | 27 |
| min | 39 | 36 | 31 | 28 | 24 | 21 | - | - | - | - | - | - | - | ||
|
16MnCr5+HH 16MnCrS5+HH |
1.7131+HH 1.7139+HH |
max | 47 | 46 | 44 | 41 | 39 | 37 | 35 | 33 | 31 | 30 | 29 | 28 | 27 |
| min | 42 | 39 | 35 | 32 | 29 | 26 | 24 | 22 | 20 | - | - | - | - | ||
|
16MnCr5+HL 16MnCrS5+HL |
1.7131+HL 1.7139+HL |
max | 44 | 43 | 40 | 37 | 34 | 32 | 30 | 28 | 26 | 25 | 24 | 23 | 22 |
| min | 39 | 36 | 31 | 28 | 24 | 21 | - | - | - | - | - | - | - | ||
USUALLY AVAILABLE EX STOCK
| M.T. COLORATION | QUALITY | HEAT TREATMENT | SURFACE | DIAMETER (mm) |
|---|---|---|---|---|
 |
16MnCr5 | Soft-annealed | rolled drawn / peeled h11 |
20-270 18-80 |
 |
16MnCr5 high machinability |
Soft-annealed | rolled peeled |
24-65 22-62 |
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