Steel 50100 QT-MART
Heat-treated state
AISI/SAE 50100 · ASTM A295
QT-MART = martempered (marquenched) & tempered, ~60 HRC
Salt-bath martempering for thin races and balls where quench distortion and cracking must be minimized.
Values for the QT-MART condition
Other 50100 tempers and conditions
50100 is listed in 8 conditions; see the grade overview at 50100.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard as-supplied bar/tube condition for machining, cold forming and ball blanking before hardening. | 390 | 650 | 25 | 195 HB | 46 W/m·K |
Hot rolled | Mill hot-rolled bar not yet spheroidized — cheapest input when the user will anneal or forge in-house. | 490 | 850 | 14 | 25 HRC | 7.8 % IACS |
Normalized | Used to break up carbide network in forgings prior to spheroidizing; not a delivery condition for finishing. | 540 | 950 | 12 | 30 HRC | 7.6 % IACS |
Cold drawn | Close-tolerance bright bar and ball/roller wire for automatic machining and cold heading before hardening. | 590 | 760 | 12 | 20 HRC | 7.8 % IACS |
Hardened + stabilizing temper 230–250 °C | Dimensionally stabilized (S0/S1-type) condition when the bearing must run above ~150 °C, at the cost of hardness. | 1,650 | 1,900 | 3 | 57 HRC | — |
Through hardened & tempered 58–62 HRC | Slightly softer/tougher bearing condition for shock-loaded rollers and small races. | 1,800 | 2,150 | 1.5 | 60 HRC | — |
QT-MARTThis page Martempered (marquenched) & tempered, ~60 HRC | Salt-bath martempering for thin races and balls where quench distortion and cracking must be minimized. | 1,800 | 2,150 | 1 | 60 HRC | 7 % IACS |
Through hardened & tempered 60–64 HRC | Standard finished bearing-race and ball condition — maximum wear and rolling-contact fatigue life on small sections. | 1,900 | 2,300 | 1 | 62 HRC | 36 W/m·K |
What is 50100 QT-MART?
50100 QT-MART is 50100 heat treated to QT-MART — salt-bath martempering for thin races and balls where quench distortion and cracking must be minimized. 50100 QT-MART has a yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 99% of steel grades. Elongation at break is 1% and the elastic modulus is 205 GPa (29.7 Msi). 50100 QT-MART has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,425°C (2,597 °F). ANN is the default condition FabDigit quotes; QT-MART is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 88/100, better than 100% of steel grades
- High strength — 1,800 MPa (261 ksi), better than 99% of steel grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 100% of steel grades
- Difficult to machine — 5/100, worse than 100% of steel grades
- Difficult to weld — 3/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
- Limited ductility — 1%, worse than 99% of steel grades
50100 QT-MART properties
Typical room-temperature values for 50100 QT-MART; 22 are specific to this condition. Other listed values are 50100 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
50100 QT-MART has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
50100 QT-MART has a yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 99% of steel grades. Elongation at break is 1% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
50100 QT-MART is rated for continuous service to 120°C (248 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
50100 QT-MART conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 50100 QT-MART takes about 33 MJ of energy and emits 2.4 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 25%.
Manufacturability7
50100 QT-MART's machinability is not recommended (5/100, worse than 100% of steel grades); weldability not recommended (3/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 50100 QT-MART
Is 50100 easy to machine?
Machine only in the spheroidize-annealed condition (~40% of B1112) with rigid setups and carbide tooling; hardened parts require grinding, honing or CBN turning.
Can 50100 be welded?
Effectively non-weldable at 1% C — if unavoidable, preheat 300–400 °C, low-hydrogen process and immediate post-weld temper.
Can 50100 be formed, bent or molded?
Cold heading/ball blanking and cold ring rolling are done in the annealed state; hot forge 1050–1150 °C and finish above ~900 °C, then slow-cool and spheroidize.
What surface finishes work on 50100?
No anodizing; protect with preservative oil, black oxide, manganese phosphate or thin dense chrome, and lap/superfinish raceways to sub-0.1 µm Ra.
50100 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 |
|---|---|---|
| CSUJ1 range 0.95–1.10 | 0.98 – 1.1 | 1.03 |
| Mn | 0.25 – 0.45 | 0.35 |
| Si | 0.15 – 0.35 | 0.25 |
| CrLowest Cr of the A295 family; JIS SUJ1 is higher at 0.90–1.20 | 0.4 – 0.6 | 0.5 |
| P | ≤ 0.03 | — |
| S | ≤ 0.02 | — |
| Niresidual max | ≤ 0.25 | — |
| Curesidual max | ≤ 0.3 | — |
| Moresidual max | ≤ 0.1 | — |
| Fe | balance | — |
50100 QT-MART — frequently asked
What is 50100 QT-MART used for?
50100 QT-MART is typically used for small bearing races and balls, instrument bearings, needle roller and pin assemblies, light-duty cam followers, thin-section thrust washers and precision bushings. In short: leanest A295 bearing steel; for small, light-duty bearings; SUJ1 equivalent.
What is the yield strength of 50100 QT-MART?
50100 QT-MART has a typical yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 50100 QT-MART easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of steel grades). Machine only in the spheroidize-annealed condition (~40% of B1112) with rigid setups and carbide tooling; hardened parts require grinding, honing or CBN turning.
Can 50100 QT-MART be welded?
Not readily — weldability is rated not recommended (3/100). Effectively non-weldable at 1% C — if unavoidable, preheat 300–400 °C, low-hydrogen process and immediate post-weld temper.
What surface finishes work on 50100 QT-MART?
No anodizing; protect with preservative oil, black oxide, manganese phosphate or thin dense chrome, and lap/superfinish raceways to sub-0.1 µm Ra.
Can 50100 QT-MART be formed, bent or molded?
Cold heading/ball blanking and cold ring rolling are done in the annealed state; hot forge 1050–1150 °C and finish above ~900 °C, then slow-cool and spheroidize.
What is the maximum service temperature of 50100 QT-MART?
50100 QT-MART is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 50100-ANN and 50100 QT60-64?
ANN is the default condition — standard as-supplied bar/tube condition for machining, cold forming and ball blanking before hardening. QT60-64: standard finished bearing-race and ball condition — maximum wear and rolling-contact fatigue life on small sections. Yield strength is 390 MPa in ANN versus 1,900 MPa in QT60-64.
Sources
- ASTM A295 / A295M — High-Carbon Anti-Friction Bearing Steel — ASTM (2014)
- JIS G 4805 — High carbon chromium bearing steels (SUJ1) — JSA (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (bearing steels) — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (hardening of high-carbon bearing steels) — ASM International (1991)
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.