Steel 4137
AISI/SAE 4137 · UNS G41370 · EN 35CrMo · JIS SCM432
4137 is a medium-carbon chromium-molybdenum alloy steel (UNS G41370) with slightly leaner alloy content than 4140, supplied to the same SAE-AISI 41xx practice including the hardenability-controlled 4137H variant.
Reference datasheet — 4137 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the QT_28_32HRC condition
4137 tempers and conditions
4137 is supplied in 10 conditions, soft to hard. QT_28_32HRC is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition, for deep machining, cold forming or before hardening. | 415 | 655 | 25 | 197 HB | 44 W/m·K |
Hot rolled | Cheapest mill condition for parts that will be heat treated after rough machining. | 430 | 700 | 22 | 14 HRC | 7.9 % IACS |
Normalized | Uniform fine-grain structure for forgings prior to machining or hardening; higher strength than annealed. | 580 | 900 | 20 | 26 HRC | — |
Cold drawn | Bright, close-tolerance bar with raised yield strength for shafts and fasteners used without further heat treatment. | 655 | 760 | 12 | 19 HRC | 7.8 % IACS |
oil quenched, high temper (~620 °C) | Tough, easily machined condition for large shafts and pressure-retaining parts needing impact resistance. | 700 | 830 | 21 | 24 HRC | — |
QT_28_32HRCDefault oil quenched, tempered ~570 °C | The standard stocked strength level: good balance of ~965 MPa tensile strength, toughness and machinability for shafts, gears and high-strength bolting. | 860 | 965 | 18 | 30 HRC | — |
H-band hardenability grade | Order this when a guaranteed Jominy hardenability band is required for heavy or safety-critical heat-treated parts. | 860 | 965 | 18 | 30 HRC | 7.8 % IACS |
oil quenched, tempered ~525 °C | Higher strength for loaded shafts, couplings and Grade-8-class fasteners where some toughness is traded for strength. | 1,000 | 1,100 | 16 | 34 HRC | — |
oil quenched, tempered ~450 °C | High-strength condition for spindles, tool holders and wear-loaded parts; toughness and weldability drop sharply. | 1,180 | 1,300 | 13 | 40 HRC | — |
oil quenched, low temper (~300 °C) | Maximum practical hardness for small sections needing wear resistance; brittle and prone to hydrogen embrittlement if plated. | 1,420 | 1,580 | 10 | 47 HRC | — |
What is 4137?
4137 is a medium-carbon chromium-molybdenum alloy steel (UNS G41370) with slightly leaner alloy content than 4140, supplied to the same SAE-AISI 41xx practice including the hardenability-controlled 4137H variant. Engineers pick it for through-hardened bolts, shafts and couplings machined from bar or forgings, with quench-and-temper bands from 22–26 HRC up to 45–50 HRC. In the default 28–32 HRC condition it gives 860 MPa yield, 965 MPa tensile, 18 % elongation and 293 HB (30 HRC), with service to about 370 °C and machinability rated 52. It has no corrosion resistance and needs preheat for welding; 4140 is the nearest and more widely stocked alternative. 4137 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,416°C (2,581 °F). 4137 has a yield strength of 860 MPa (125 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 89% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
What is 4137 used for?
- high-strength bolts
- shafts
- couplings
Advantages
- High strength — 860 MPa (125 ksi), better than 89% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
4137 properties
Typical room-temperature values for 4137-QT_28_32HRC; bars are the position among steel grades.
Physical3
4137 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,416°C (2,581 °F).
Mechanical16
4137 has a yield strength of 860 MPa (125 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 89% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4137 is rated for continuous service to 370°C (698 °F). It conducts heat at 42.6 W/m·K (24.6 BTU/hr·ft·°F), worse than 51% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
4137 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 4137 takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 35%.
Manufacturability7
4137's machinability is fair (52/100, better than 52% of steel grades); weldability fair (40/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 4137 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4137
Is 4137 easy to machine?
Machine in the annealed or 28–32 HRC condition with rigid setups, carbide inserts and generous coolant; above ~38 HRC expect coated carbide/CBN and reduced feeds.
Can 4137 be welded?
Weldable with low-hydrogen electrodes but requires 250–350 °C preheat, controlled interpass and post-weld temper below the part's tempering temperature; carbon equivalent ~0.75.
Can 4137 be formed, bent or molded?
Hot forge 1100–1230 °C then normalize; cold forming only in the annealed state with generous bend radii.
4137 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CSAE J404 / ASTM A29 | 0.35 – 0.4 | 0.37 |
| Mn | 0.7 – 0.9 | 0.8 |
| Si | 0.15 – 0.35 | 0.25 |
| Cr | 0.8 – 1.1 | 0.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 4137?
Not anodizable — protect with black oxide, phosphate, zinc or zinc-nickel plating (bake for hydrogen relief above 32 HRC), nitriding gives a hard, wear-resistant case.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 4137 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 4137 cost?
4137 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
4137 — frequently asked
What is 4137 used for?
4137 is typically used for high-strength bolts, shafts and couplings. In short: leaner 4140 substitute; through-hardens to 50 HRC; nitriding-friendly Cr-Mo steel.
What is the yield strength of 4137?
4137 has a typical yield strength of 860 MPa (125 ksi) and a tensile strength of 965 MPa (140 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 4137 easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% of steel grades). Machine in the annealed or 28–32 HRC condition with rigid setups, carbide inserts and generous coolant; above ~38 HRC expect coated carbide/CBN and reduced feeds.
Can 4137 be welded?
With care — weldability is rated fair (40/100). Weldable with low-hydrogen electrodes but requires 250–350 °C preheat, controlled interpass and post-weld temper below the part's tempering temperature; carbon equivalent ~0.75.
What surface finishes work on 4137?
Not anodizable — protect with black oxide, phosphate, zinc or zinc-nickel plating (bake for hydrogen relief above 32 HRC), nitriding gives a hard, wear-resistant case.
Can 4137 be formed, bent or molded?
Hot forge 1100–1230 °C then normalize; cold forming only in the annealed state with generous bend radii.
What is the maximum service temperature of 4137?
4137 is rated for continuous use to about 370°C (698 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 4137 QT_28_32HRC and 4137-ANN?
QT_28_32HRC is the default condition — the standard stocked strength level: good balance of ~965 MPa tensile strength, toughness and machinability for shafts, gears and high-strength bolting. ANN: softest condition, for deep machining, cold forming or before hardening. Yield strength is 860 MPa in QT_28_32HRC versus 415 MPa in ANN.
How much does 4137 cost?
4137 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- SAE J1268 — Hardenability Bands for Alloy H-Steels — SAE International (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating — ASM International (1991)
- GB/T 3077 — (35CrMo equivalent) — SAC (2015)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.