Steel 4137-ANN (Annealed)
Heat-treated state
AISI/SAE 4137 · UNS G41370 · EN 35CrMo · JIS SCM432
Softest condition, for deep machining, cold forming or before hardening.
Values for the ANN 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 |
|---|---|---|---|---|---|---|
ANNThis page 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-ANN?
4137-ANN is 4137 heat treated to ANN — softest condition, for deep machining, cold forming or before hardening. 4137-ANN has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 56% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi). 4137-ANN 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; ANN is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
4137-ANN properties
Typical room-temperature values for 4137-ANN; 14 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-ANN 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-ANN has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 56% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4137-ANN is rated for continuous service to 370°C (698 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
4137-ANN 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-ANN 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-ANN's machinability is good (60/100, better than 83% of steel grades); weldability fair (50/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 4137-ANN
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-ANN — frequently asked
What is 4137-ANN used for?
4137-ANN 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-ANN?
4137-ANN has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 56% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 4137-ANN easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% 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-ANN be welded?
With care — weldability is rated fair (50/100). 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-ANN?
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-ANN 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-ANN?
4137-ANN 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.
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.