Steel SNB7 Annealed
Temper
Bar supplied soft for deep machining or thread rolling before final quench and temper.
Values for the Annealed condition
Other SNB7 tempers and conditions
SNB7 is listed in 7 conditions; see the grade overview at SNB7.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedThis page soft condition for machining or cold work | Bar supplied soft for deep machining or thread rolling before final quench and temper. | 415 | 655 | 25 | 197 HB | — |
Hot rolled | Raw bar or forging stock bought for in-house heat treatment of studs and bolts. | 450 | 750 | 20 | 18 HRC | 7.8 % IACS |
Q&T 100–180 mm dia | Heavy anchor studs and large flange bolting; lowest guaranteed strength class. | 600 | 800 | 22 | 22 HRC | — |
Q&T ≤235 HB | Choose when NACE MR0175 sour-service hardness limits apply; strength is traded for SSC resistance. | 600 | 760 | 20 | 19 HRC | — |
air cooled from austenitizing, pre-machining stock | Uniform-grain intermediate condition for forgings before final Q&T; not a delivery condition for B7 fasteners. | 655 | 1,020 | 18 | 32 HRC | 7.8 % IACS |
Q&T 64–100 mm dia | Larger studs where hardenability limits properties to 655 MPa minimum yield. | 745 | 880 | 21 | 26 HRC | — |
Q&T ≤64mmDefault Q&T ≤64 mm dia | Standard stocked condition for studs, bolts and bar up to 64 mm — 720 MPa minimum yield. | 830 | 950 | 20 | 30 HRC | — |
What is SNB7 Annealed?
SNB7 Annealed is SNB7 in the Annealed temper — bar supplied soft for deep machining or thread rolling before final quench and temper. SNB7 Annealed 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). SNB7 Annealed 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). Q&T ≤64mm is the default condition FabDigit quotes; Annealed is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
SNB7 Annealed properties
Typical room-temperature values for SNB7 Annealed; 12 are specific to this condition. Other listed values are SNB7 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SNB7 Annealed 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
SNB7 Annealed 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
SNB7 Annealed is rated for continuous service to 425°C (797 °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
SNB7 Annealed 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 SNB7 Annealed takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability6
SNB7 Annealed's machinability is good (58/100, better than 75% of steel grades); weldability fair (40/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SNB7 Annealed
Is SNB7 easy to machine?
Machine in annealed condition where possible; at 28–32 HRC use rigid setups, coated carbide, ~80–120 m/min and generous coolant — thread rolling before hardening gives best fatigue life.
Can SNB7 be welded?
Not intended for welding; if unavoidable use low-hydrogen consumables, 250–350 °C preheat and 620–680 °C PWHT to avoid hard HAZ and hydrogen cracking.
Can SNB7 be formed, bent or molded?
Hot forge at 1100–1200 °C then normalize; cold forming only in the annealed state, with re-quench and temper afterwards to restore B7 properties.
What surface finishes work on SNB7?
Bare surfaces rust quickly — zinc plate, hot-dip galvanize (bake to relieve hydrogen), phosphate-and-oil or PTFE coat; keep plating baking cycles per ASTM F1941 to avoid hydrogen embrittlement.
SNB7 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 |
|---|---|---|
| CJIS G4107 SNB7 0.38–0.48 | 0.37 – 0.49 | 0.42 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.65 – 1.1 | 0.88 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Cr | 0.75 – 1.2 | 0.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| Fe | balance | — |
SNB7 Annealed — frequently asked
What is SNB7 Annealed used for?
SNB7 Annealed is typically used for high-temperature bolts, studs and flange fasteners. In short: standard B7 bolting steel; 4140 chemistry, sized tempers; strength to 425 °C.
What is the yield strength of SNB7 Annealed?
SNB7 Annealed 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 7 listed tempers.
Is SNB7 Annealed easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machine in annealed condition where possible; at 28–32 HRC use rigid setups, coated carbide, ~80–120 m/min and generous coolant — thread rolling before hardening gives best fatigue life.
Can SNB7 Annealed be welded?
With care — weldability is rated fair (40/100). Not intended for welding; if unavoidable use low-hydrogen consumables, 250–350 °C preheat and 620–680 °C PWHT to avoid hard HAZ and hydrogen cracking.
What surface finishes work on SNB7 Annealed?
Bare surfaces rust quickly — zinc plate, hot-dip galvanize (bake to relieve hydrogen), phosphate-and-oil or PTFE coat; keep plating baking cycles per ASTM F1941 to avoid hydrogen embrittlement.
Can SNB7 Annealed be formed, bent or molded?
Hot forge at 1100–1200 °C then normalize; cold forming only in the annealed state, with re-quench and temper afterwards to restore B7 properties.
What is the maximum service temperature of SNB7 Annealed?
SNB7 Annealed 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 SNB7 Q&T ≤64mm and SNB7-HR?
Q&T ≤64mm is the default condition — standard stocked condition for studs, bolts and bar up to 64 mm — 720 MPa minimum yield. HR: raw bar or forging stock bought for in-house heat treatment of studs and bolts. Yield strength is 830 MPa in Q&T ≤64mm versus 450 MPa in HR.
Sources
- JIS G 4107 Alloy steel bolting materials for high temperature service — JSA (2019)
- ASTM A193/A193M Alloy-Steel and Stainless Steel Bolting for High Temperature Service — ASTM (2023)
- ASM Handbook Vol.1 Properties and Selection: Irons, Steels and High-Performance Alloys (4140/4142) — ASM International (1990)
- ASM Handbook Vol.16 Machining — ASM International (1989)
- GB/T 3077 (42CrMo) — SAC (2015)
- NACE MR0175 / ISO 15156 materials for H2S-containing environments — NACE/ISO (2020)
- 42CrMo — Mysteel / 1688 (2026)
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.