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Resources/Materials & grades/4145

Materials & grades

4145 / 4145H / SCM445 chromium-molybdenum steel (drill collar grade)

SAE 4145 is a medium-carbon chromium-molybdenum alloy steel, the higher-carbon relative of 4140, with 0.43–0.48% carbon. It is used hardened and tempered for heavy shafts and oilfield tools, and drill collar bar is sold as 4145H modified.

Names by standard

What it is called in each region

RegionSystemDesignationתקןMatch
USAAISI/SAE4145SAE J404; ASTM A29 (bar)Same material
UNSG41450—Same material
AISI/SAE4145HHardenability-band version of 4145. Drill collar makers sell bar as 4145H modified; the limits behind "modified" come from the buyer's or maker's specification, not from SAE J404.SAE hardenability-band gradeClosest equivalent
UKBS 970-3 (1991)708M40Nearest BS 970 grade, but carbon is lower than 4145 (see the 4140 page). No separate BS 970 name for 4145 was found in the sources checked. BS 970 is superseded by BS EN 10083.BS 970-3Closest equivalent
EUEN 10027-1 name50CrMo4 (1.7228)Carbon is 0.46–0.54%, above the 4145 range of 0.43–0.48%, and manganese is lower (0.50–0.80%).EN 10083-3; EN ISO 683-2Closest equivalent
EN 10027-1 name42CrMo4 (1.7225)Carbon is 0.38–0.45%, below the 4145 range. 42CrMo4 is the 4140 page's own European name.EN 10083-3; EN ISO 683-2Closest equivalent
הודוIS 157042Cr4Mo2Nearest Indian chromium-molybdenum grade. Carbon is 0.38–0.45%, so it sits below 4145. IS 1570 (Part 4) has no grade at 0.43–0.48% carbon with chromium and molybdenum.IS 1570 (Part 4):1988Closest equivalent
JapanJIS G 4053SCM445Same carbon range, 0.43–0.48%. Kobelco's cross-reference table lists 4145 and 4147 against SCM445.JIS G 4053Equivalent
JIS G 4052SCM445HHardenability-guaranteed version. Misumi's JIS table lists it against 4145H and 4147H.JIS G 4052Closest equivalent

On equivalence

  • No EN grade matches 4145 exactly. 42CrMo4 (0.38–0.45% C) sits just below it and 50CrMo4 (0.46–0.54% C) just above it, so both are "closest".
  • SCM445 (JIS G 4053) is the usual Japanese match with the same carbon range. SCM445 allows 0.60–0.90% manganese and 0.90–1.20% chromium against 0.75–1.00% and 0.80–1.10% for 4145.
  • India: IS 1570 (Part 4):1988 lists no chromium-molybdenum grade at 0.43–0.48% carbon. 42Cr4Mo2 is the nearest, with lower carbon; check strength and hardness on the order.
  • UK: no BS 970 name for 4145 was confirmed. 708M40 is the nearest BS 970 grade and carries less carbon.
  • Silicon: AZoM gives 0.15–0.30% for 4145, while the Central Steel & Wire catalog (via Wikipedia) gives 0.15–0.35%.
  • 4145H adds a guaranteed hardenability band. "4145H modified" on a drill collar order refers to limits agreed between buyer and maker, so quote the purchase specification.

Chemical composition

Composition limits, mass %

Element4145USA · SAE J404 / ASTM A29 (bar)50CrMo4 (1.7228)EU · EN 10083-3 (50CrMo4, closest match)42Cr4Mo2הודו · IS 1570 (Part 4):1988 (closest match)SCM445Japan · JIS G 4053 (as tabulated by Kobelco)
C0.43–0.480.46–0.540.38–0.450.43–0.48
Si0.15–0.35≤0.400.10–0.350.15–0.35
Mn0.75–1.000.50–0.800.60–0.900.60–0.90
P≤0.035——≤0.030
S≤0.040——≤0.030
Cr0.80–1.100.90–1.200.90–1.200.90–1.20
Ni———≤0.25
Mo0.15–0.250.15–0.300.15–0.300.15–0.30

Mechanical properties

Strength and hardness

ConditionTensile strengthYield strengthElongationHardness
Typical hardness, condition not stated by the sourceTypical, not a specified valueAZoM, AISI 4145 alloy steel (UNS G41450)———208 HB
Quenched and tempered, drill collar bar (4145H modified)Minimums for 3 1/8–6 7/8 in outside diameter as published by a drill collar maker citing API Spec 7-1; heat treated to 285–341 HB; Charpy impact at least 40 ft·lbParveen drill collar catalogue (secondary; API Spec 7-1 not read)≥965 MPa≥140 ksi≥758 MPa≥110 ksi≥13 %≥285 HB
Quenched and tempered, drill collar bar (4145H modified)Minimums for 7–10 in outside diameter as published by a drill collar maker citing API Spec 7-1 (NOV lists the same strengths and a 285 HB minimum for 7 in and above); heat treated to 285–341 HB; Charpy impact at least 40 ft·lbParveen drill collar catalogue, NOV drill collar data and Command Tubular drill collars (API Spec 7-1 not read)≥931 MPa≥135 ksi≥689 MPa≥100 ksi≥13 %≥285 HB

In practice

Behaviour, heat treatment and uses

Characteristics

  • Carbon of 0.43–0.48% puts 4145 between 4140 (0.38–0.43%) and 4150 (0.48–0.53%). The alloying is the same as 4140: 0.80–1.10% chromium and 0.15–0.25% molybdenum.
  • Machinability is rated 60 (AISI 1212 = 100) for annealed and cold drawn bar (AZoM, typical).
  • Weldability is poor. DEW states that the comparable 50CrMo4 should not be used in welded construction, and AZoM advises post-weld heat treatment for 4150. Plan any weld repair with preheat and post-weld heat treatment.
  • Drill collar makers specify bar that is ultrasonically tested and fully heat treated to 285–341 HB with a Charpy value of at least 40 ft·lb.
  • Hardenability testing of SCM445H is carried out from a normalizing temperature of 870 °C and a quenching temperature of 845 °C (Kobelco).

Heat treatment

  • Hardenability test (JIS SCM445H): normalize at 870 °C, then quench from 845 °C (Kobelco).
  • Guidance from the comparable European grade 50CrMo4 (DEW): normalize at 840–880 °C and air cool; harden at 830–860 °C in oil; temper at 540–680 °C.
  • Drill collar bar is supplied fully heat treated to 285–341 HB. The tempering temperature is chosen to reach that hardness band.
  • Heat treatment limits for 4145 itself were not found in a readable standard or mill sheet. Take the cycle from the supplier's data for the exact grade.

שימושים אופייניים

  • Drill collars and other downhole oilfield tools (sold as 4145H modified)
  • Heavy shafts and mandrels
  • Firearm parts, clutch and flywheel components and roll cages (Wikipedia, 41xx steel)
  • High-strength bolting: JIS G 4107 SNB 7 allows 0.38–0.48% carbon, which spans 4140 and 4145

Alloy and case-hardening steels

Similar grades compared

דרגהC %Mn %Cr %Ni %Tensile, first listed condition
41450.43–0.480.75–1.000.80–1.10≤0.25≥965 MPa
4130 / 25CrMo40.28–0.330.40–0.600.80–1.10≤0.25590–760 MPa
4135 / 34CrMo40.33–0.380.70–0.900.80–1.10≤0.251000–1200 MPa
4140 / 42CrMo40.38–0.430.75–1.000.80–1.10≤0.25655 MPa
4150 / 50CrMo40.48–0.530.75–1.000.80–1.10≤0.25731 MPa
4340 / EN240.38–0.430.60–0.800.70–0.901.65–2.00745 MPa
5140 / 41Cr40.38–0.430.70–0.900.70–0.90≤0.25570 MPa
6150 / 51CrV40.48–0.530.70–0.900.80–1.10≤0.40670 MPa
8640 / SNCM2400.38–0.430.75–1.000.40–0.600.40–0.701000–1413 MPa
16MnCr50.13–0.180.70–0.900.70–0.90≤0.25≥1000 MPa

Composition from the US standard where one exists, otherwise the first standard listed on each grade's page. Strength conditions differ between grades; open a grade for its full table.

תשובות לשאלות

Common questions

What is the equivalent of 4145 steel?

No standard names a single exact match. The closest are SCM445 in Japan, 50CrMo4 (1.7228) or 42CrMo4 (1.7225) in Europe and 42Cr4Mo2 in India. SCM445 is nearest because it has the same 0.43–0.48% carbon range.

What is the difference between 4140 and 4145?

Carbon. 4145 holds 0.43–0.48% carbon and 4140 holds 0.38–0.43%, while manganese, chromium and molybdenum limits are the same. The extra carbon raises the hardness and strength that can be reached after quenching and tempering.

Is 4145H the same as 4145?

4145H is the same steel sold to a guaranteed hardenability band. Drill collar bar called 4145H modified uses limits agreed between buyer and maker, so the purchase specification decides what is supplied.

What steel are drill collars made from?

Makers describe drill collar bar as 4145H modified chromium-molybdenum steel. One maker quotes a minimum yield of 110 ksi and tensile of 140 ksi for 3 1/8–6 7/8 in outside diameter, citing API Spec 7-1, with 285–341 HB hardness.

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פתחו פנייה

Keep reading

4140 / 42CrMo4AISI 4140 is a medium-carbon chromium-molybdenum alloy steel, normally used hardened and tempered for shafts, gears and high-strength bolts.4150 / 50CrMo4SAE 4150 is a higher-carbon chromium-molybdenum alloy steel with 0.48–0.53% carbon, used hardened and tempered for shafts, gears and firearm barrels.4340 / EN24AISI 4340 is a medium-carbon nickel-chromium-molybdenum alloy steel, used hardened and tempered where high strength and toughness are needed in large sections.4135 / 34CrMo44135 is a chromium-molybdenum steel with about 0.35 % carbon, hardened and tempered for crankshafts, axles and other highly stressed parts.Quenching and temperingQuenching and tempering hardens steel by cooling it rapidly from the austenite range to form martensite, then reheats it below Ac1 to trade some hardness for toughness.A193 B7ASTM A193 Grade B7 is a quenched and tempered chromium-molybdenum steel (AISI 4140 or 4142 type) for studs and bolts in high-pressure and high-temperature service, with a minimum tensile strength of 125 ksi up to 2½ in.SAE / AISI numbersA four-digit SAE/AISI number such as 1045 or 4140 names a carbon or alloy steel by its chemistry: the first two digits identify the steel family and the last two give the nominal carbon content in hundredths of a percent.EN 10027 names and numbersEuropean steels carry two identifiers under EN 10027: a steel name (Part 1) such as S235JR, C45 or 42CrMo4 that describes the steel's use or chemistry, and a material number (Part 2) such as 1.0503 or 1.7225.IS 1570 and Indian designationsIndian steel names follow the letter-symbol code in IS 1762 (Part 1), which the IS 1570 schedules use: 45C8 means about 0.45% carbon, C for carbon steel and about 0.8% manganese, while alloy names such as 40Cr4Mo3 list each element with a multiplied content figure.JIS steel designationsJapanese JIS steel symbols start with S for steel and add letters for the steel family or its use, but the number means different things in different standards.

References

Sources

  1. AZoM, AISI 4145 Alloy Steel (UNS G41450) — Composition, hardness, machinability rating and related ASTM/SAE designations.
  2. SAE J404: Chemical compositions of SAE alloy steels — Governs the SAE alloy-steel composition limits. Values here are as tabulated by AZoM and the Central Steel & Wire catalog.
  3. Wikipedia, 41xx steel (SAE composition table citing the Central Steel & Wire catalog) — SAE bar composition for 4145 and 4150; example applications.
  4. Kobelco: wire rod and bar specification tables (JIS G 4053 alloy steels for machine structure, revision of 20 Nov 2008; JIS G 4107 bolting steels) — JIS composition tables and the JIS-to-ISO/AISI cross-reference table.
  5. Misumi: comparison of JIS and related overseas steel standards — Cross-reference of JIS G 4053 and G 4052 grades to ISO, AISI/SAE and EN names.
  6. IS 1570 (Part 4):1988 Schedules for wrought steels, alloy steels (public copy) — Table 1 composition limits and the footnote cross-references to AISI and DIN grades.
  7. Deutsche Edelstahlwerke (Swiss Steel Group), Werkstoffdatenblatt 1.7228 / 50CrMo4 — 50CrMo4 composition, heat treatment and weldability statement.
  8. Parveen Industries, drill collars (AISI 4145H modified, API 7) — Drill collar properties and hardness band as published by a maker.
  9. Total Materia, AISI 4145 — SCM445 and SNB 7 listed as official equivalents (equivalence list only).
  10. NOV, Drill Collars — Minimum yield, tensile and hardness by drill collar outside diameter (285 HB minimum for 3 1/8 in and above).
  11. Command Tubular, Drill Collars — Modified AISI 4145H bar, API Spec 7-1 properties, 285–341 BHN guaranteed.

Values summarize published limits and typical data. The governing standard and the current edition control; check them before specifying.