Steel 42CrMo Q&T+Nitrided
Finish state
GB 42CrMo
Q&T+Nitrided = q&T + gas/plasma nitrided
Choose for wear surfaces (gears, spindles, hydraulic rods) where the Q&T core strength is kept and a hard, distortion-free case is added; hardness values below are surface, core equals Q&T.
Values for the Q&T+Nitrided condition
Other 42CrMo tempers and conditions
42CrMo is listed in 9 conditions; see the grade overview at 42CrMo.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/spheroidize anneal, ≤217 HB | Softest condition — choose for heavy machining, deep drilling or cold upsetting before final hardening. | 450 | 700 | 22 | 200 HB | — |
HRDefault Hot rolled | Cheapest stock form for parts that will be heat treated (or lightly loaded) after machining. | 570 | 880 | 15 | 22 HRC | — |
austenitize ~860 °C, air cool | Uniform fine-grain structure for forgings and large sections before final Q&T or for moderate-strength service. | 650 | 1,000 | 18 | 29 HRC | — |
Cold rolled | Thin strip/plate form (often annealed after rolling) for stamped or laser-cut blanks that will be hardened later. | 660 | 820 | 12 | 23 HRC | 7.8 % IACS |
Cold drawn | Close tolerance, bright surface bar for shafting and turned parts that need little further machining. | 780 | 930 | 11 | 26 HRC | — |
Tempered high for toughness / sour service | Pick when NACE MR0175 (≤22 HRC alternative not required) or maximum impact toughness and machinability after heat treatment matter. | 860 | 1,000 | 17 | 30 HRC | — |
Quenched and tempered | Standard high-strength delivery condition for shafts, gears and bolting where 1080 MPa min tensile is specified. | 960 | 1,120 | 14 | 36 HRC | — |
Q&T+NitridedThis page Q&T + gas/plasma nitrided | Choose for wear surfaces (gears, spindles, hydraulic rods) where the Q&T core strength is kept and a hard, distortion-free case is added; hardness values below are surface, core equals Q&T. | 960 | 1,120 | 13 | 36 HRC | — |
Tempered for higher strength | Highest practical hardness that keeps useful toughness — gears, couplings, high-strength studs and drill collars. | 1,050 | 1,180 | 12 | 36 HRC | — |
What is 42CrMo Q&T+Nitrided?
42CrMo Q&T+Nitrided is 42CrMo supplied in the Q&T+Nitrided condition — choose for wear surfaces (gears, spindles, hydraulic rods) where the Q&T core strength is kept and a hard, distortion-free case is added; hardness values below are surface, core equals Q&T. 42CrMo Q&T+Nitrided has a yield strength of 960 MPa (139 ksi) and a tensile strength of 1,120 MPa (162 ksi) — stronger than 91% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi). 42CrMo Q&T+Nitrided 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). HR is the default condition FabDigit quotes; Q&T+Nitrided is available on request or by drawing note.
Advantages
- High strength — 960 MPa (139 ksi), better than 91% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
Limitations
- Difficult to machine — 10/100, worse than 99% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
42CrMo Q&T+Nitrided properties
Typical room-temperature values for 42CrMo Q&T+Nitrided; 10 are specific to this condition. Other listed values are 42CrMo reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
42CrMo Q&T+Nitrided 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).
Mechanical15
42CrMo Q&T+Nitrided has a yield strength of 960 MPa (139 ksi) and a tensile strength of 1,120 MPa (162 ksi) — stronger than 91% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
42CrMo Q&T+Nitrided is rated for continuous service to 450°C (842 °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
42CrMo Q&T+Nitrided conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of 42CrMo Q&T+Nitrided takes about 29 MJ of energy and emits 2.3 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability7
42CrMo Q&T+Nitrided's machinability is not recommended (10/100, worse than 99% of steel grades); weldability poor (30/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 42CrMo Q&T+Nitrided
Is 42CrMo easy to machine?
Machine in the annealed or ≤32 HRC Q&T condition with rigid setups, carbide inserts and generous coolant; above 38 HRC switch to grinding or CBN.
Can 42CrMo be welded?
Weldable with low-hydrogen consumables but requires 200–350 °C preheat, controlled interpass temperature and immediate post-weld temper (~600 °C) to avoid HAZ cracking.
Can 42CrMo be formed, bent or molded?
Hot forge/upset at 1150–850 °C then normalize; cold bending is limited — anneal first and use generous radii.
What surface finishes work on 42CrMo?
No anodizing; use black oxide, manganese phosphate, zinc or hard-chrome plating (bake to avoid hydrogen embrittlement above ~35 HRC), nitriding or paint for corrosion protection.
42CrMo 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 |
|---|---|---|
| C | 0.38 – 0.45 | 0.42 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.5 – 0.8 | 0.65 |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.25 | 0.2 |
| Niresidual limit | ≤ 0.3 | |
| Curesidual limit | ≤ 0.3 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
42CrMo Q&T+Nitrided — frequently asked
What is 42CrMo Q&T+Nitrided used for?
42CrMo Q&T+Nitrided is typically used for drive shafts, crankshafts, gears and pinions, high-strength bolting and studs, hydraulic cylinder rods and drill collars. In short: workhorse Cr-Mo machining bar.
What is the yield strength of 42CrMo Q&T+Nitrided?
42CrMo Q&T+Nitrided has a typical yield strength of 960 MPa (139 ksi) and a tensile strength of 1,120 MPa (162 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 42CrMo Q&T+Nitrided easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 99% of steel grades). Machine in the annealed or ≤32 HRC Q&T condition with rigid setups, carbide inserts and generous coolant; above 38 HRC switch to grinding or CBN.
Can 42CrMo Q&T+Nitrided be welded?
Not readily — weldability is rated poor (30/100). Weldable with low-hydrogen consumables but requires 200–350 °C preheat, controlled interpass temperature and immediate post-weld temper (~600 °C) to avoid HAZ cracking.
What surface finishes work on 42CrMo Q&T+Nitrided?
No anodizing; use black oxide, manganese phosphate, zinc or hard-chrome plating (bake to avoid hydrogen embrittlement above ~35 HRC), nitriding or paint for corrosion protection.
Can 42CrMo Q&T+Nitrided be formed, bent or molded?
Hot forge/upset at 1150–850 °C then normalize; cold bending is limited — anneal first and use generous radii.
What is the maximum service temperature of 42CrMo Q&T+Nitrided?
42CrMo Q&T+Nitrided is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 42CrMo-HR and 42CrMo-CD?
HR is the default condition — cheapest stock form for parts that will be heat treated (or lightly loaded) after machining. CD: close tolerance, bright surface bar for shafting and turned parts that need little further machining. Yield strength is 570 MPa in HR versus 780 MPa in CD.
Can FabDigit make parts in 42CrMo Q&T+Nitrided?
Yes — 42CrMo Q&T+Nitrided is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 3077 Alloy structural steels — SAC (2015)
- EN 10083-3 (42CrMo4, 1.7225) — CEN (2006)
- ASTM A29/A29M & SAE J404 (4140) — ASTM / SAE (2020)
- ASM Handbook Vol.1 Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 Fatigue and Fracture — ASM International (1996)
- Machinery's Handbook, machinability ratings — Industrial Press (2020)
- NACE MR0175/ISO 15156 hardness limits for sour service — NACE/ISO (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.