Steel 4137-HR (Hot rolled)
Supply condition
AISI/SAE 4137 · UNS G41370 · EN 35CrMo · JIS SCM432
Cheapest mill condition for parts that will be heat treated after rough machining.
Values for the HR condition
Other 4137 tempers and conditions
4137 is listed in 10 conditions; see the grade overview at 4137.
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 |
HRThis page 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-HR?
4137-HR is 4137 supplied in the HR condition — cheapest mill condition for parts that will be heat treated after rough machining. 4137-HR has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 51% of steel grades. Elongation at break is 22% and the elastic modulus is 205 GPa (29.7 Msi). 4137-HR 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). QT_28_32HRC is the default condition FabDigit quotes; HR is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
4137-HR properties
Typical room-temperature values for 4137-HR; 23 are specific to this condition. Other listed values are 4137 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
4137-HR 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-HR has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 51% of steel grades. Elongation at break is 22% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4137-HR is rated for continuous service to 425°C (797 °F). It conducts heat at 42.7 W/m·K (24.7 BTU/hr·ft·°F), better than 50% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
4137-HR conducts electricity at 7.9 % IACS, better than 50% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 4137-HR 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-HR's machinability is good (58/100, better than 75% of steel grades); weldability fair (45/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 4137-HR
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.
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.
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 | — |
4137-HR — frequently asked
What is 4137-HR used for?
4137-HR 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-HR?
4137-HR has a typical yield strength of 430 MPa (62.4 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 51% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 4137-HR easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% 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-HR be welded?
With care — weldability is rated fair (45/100). 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-HR?
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-HR 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-HR?
4137-HR is rated for continuous use to about 425°C (797 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.