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Stainless Steel 1.4123 +QT-HT

Heat-treated state

EN 1.4123

+QT-HT = +QT high tempered ~500–525 °C (secondary hardening) 57–59 HRC

Pick for bearings and parts running hot (up to ~350–400 °C) or when dimensional stability after nitriding/coating cycles is required.

High cost $$$$
Request a quote in 1.4123 +QT-HT1.4123 overview

Values for the +QT-HT condition

Other 1.4123 tempers and conditions

1.4123 is listed in 5 conditions; see the grade overview at 1.4123.

Compare all 5 conditionsHide
Condition · open for datasheetBest forYield MPaTensile MPaElong. %HardnessConductivity
+AC
Spheroidize annealed
Choose when the softest, most machinable structure is needed for deep drilling, thread rolling or cold forming of bearing-ring blanks.5408001821 HRC—
+ADefault
Annealed
Standard stock condition for machining of blanks before hardening; max hardness limited for turning and drilling.6008801425 HRC—
+QT52
+QT 50–54 HRC
Use for shafts, cages, pump and valve components where impact toughness matters more than peak wear resistance.1,5001,750752 HRC—
+QT-HTThis page
+QT high tempered ~500–525 °C (secondary hardening) 57–59 HRC
Pick for bearings and parts running hot (up to ~350–400 °C) or when dimensional stability after nitriding/coating cycles is required.1,8002,100458 HRC—
+QT58
+QT 58–60 HRC
Standard bearing condition: maximum hardness and rolling-contact fatigue life for corrosion-exposed bearings and valve parts up to ~200 °C.1,8502,200359 HRC—

What is 1.4123 +QT-HT?

1.4123 +QT-HT is 1.4123 heat treated to +QT-HT — pick for bearings and parts running hot (up to ~350–400 °C) or when dimensional stability after nitriding/coating cycles is required. 1.4123 +QT-HT has a yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,100 MPa (305 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 4% and the elastic modulus is 205 GPa (29.7 Msi). 1.4123 +QT-HT has a density of 7.68 g/cm³ (0.277 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,400°C (2,552 °F). +A is the default condition FabDigit quotes; +QT-HT is available on request or by drawing note.

Advantages

  • High strength — 1,800 MPa (261 ksi), better than 100% of stainless steel grades
  • Polishes to a fine finish — 85/100, better than 97% of stainless steel grades

Limitations

  • Limited ductility — 4%, worse than 100% of stainless steel grades
  • Difficult to machine — 8/100, worse than 100% of stainless steel grades
  • Difficult to weld — 20/100, worse than 95% of stainless steel grades
  • Needs corrosion protection — 46/100, worse than 82% of stainless steel grades
  • Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades

1.4123 +QT-HT properties

Typical room-temperature values for 1.4123 +QT-HT; 12 are specific to this condition. Other listed values are 1.4123 reference data and may not represent this condition. Bars are the position among stainless steel grades.

Physical3

1.4123 +QT-HT has a density of 7.68 g/cm³ (0.277 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,400°C (2,552 °F).

Density7.68 g/cm³0.28 lb/in³
Melting Point (Solidus)1,400°C2,552 °F
Liquidus Temperature1,470°C2,678 °F

Mechanical15

1.4123 +QT-HT has a yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,100 MPa (305 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 4% and the elastic modulus is 205 GPa (29.7 Msi).

Elastic (Young's) Modulus205 GPa29.7 Msi
Shear Modulus80 GPa11.6 Msi
Bulk Modulus160 GPa23.2 Msi
Poisson's Ratio0.29
Tensile Strength (Ultimate)2,100 MPa305 ksi
Yield Strength (0.2% offset)1,800 MPa261 ksi
Elongation at Break4%
Reduction in Area35%
Compressive Strength700 MPa102 ksi
Shear Strength550 MPa79.8 ksi
Fatigue Strength (Endurance Limit)800 MPa116 ksi
Charpy V-Notch Impact (RT)10 J7.4 ft·lbf
Hardness, Brinell255 HB
Hardness, Rockwell C58 HRC
Hardness, Vickers660 HV

Thermal6

1.4123 +QT-HT is rated for continuous service to 400°C (752 °F). It conducts heat at 20 W/m·K (11.6 BTU/hr·ft·°F), better than 74% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).

Thermal Conductivity20 W/m·K11.6 BTU/hr·ft·°F
Specific Heat Capacity460 J/kg·K0.11 BTU/lb·°F
Thermal Expansion (CTE, 20–100 °C)10.5 µm/m·K5.8 µin/in·°F
Latent Heat of Fusion270 J/g116 BTU/lb
Max Service Temperature (continuous)400°C752 °F
Min Service Temperature-100°C-148 °F

Electrical3

1.4123 +QT-HT conducts electricity at 2.5 % IACS, better than 75% of stainless steel grades.

Electrical Conductivity2.5 % IACS
Electrical Resistivity7×10⁻⁷ Ω·m27.6 µΩ·in
Magnetic Responseferromagnetic

Chemical & Environmental3

Corrosion resistance is fair (46/100), worse than 82% of stainless steel grades.

Galvanic Potential (seawater, vs SCE)-0.25 V
Corrosion ResistanceFair46/100
Chemical Resistance SummaryGood resistance to fresh water, humid air, aviation fuel, lubricating oils and mild organic acids; nitrogen alloying raises pitting resistance above 440C, but it is not suitable for chlorides in stagnant/crevice conditions, seawater immersion or reducing acids (HCl, H2SO4).

Sustainability4

Producing a kilogram of 1.4123 +QT-HT takes about 60 MJ of energy and emits 4.8 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 25%.

Embodied Energy (primary production)60 MJ/kg25,795 BTU/lb
Embodied Carbon (primary production)4.8 kg CO₂/kg
Embodied Water200 L/kg24 gal/lb
Typical Recycled Content25%

Manufacturability8

1.4123 +QT-HT's machinability is not recommended (8/100, worse than 100% of stainless steel grades); weldability poor (20/100); formability poor (30/100).

MachinabilityNot recommended8/100
Machinability Rating (AISI 1212 = 100 %)40%
WeldabilityPoor20/100
Formability (cold)Poor30/100
CastabilityPoor30/100
Brazeability / SolderabilityFair45/100
PolishabilityExcellent85/100
Anodizing Responsen/a — ferrous alloy; use passivation (AMS 2700 nitric/citric) or black oxide instead

Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.

Working with 1.4123 +QT-HT

Is 1.4123 easy to machine?

Machine in the annealed/spheroidized condition with rigid setups, sharp coated carbide and generous coolant; after hardening only grinding, honing, EDM or hard turning with CBN is practical.

Can 1.4123 be welded?

Essentially not weldable for structural use — high carbon plus nitrogen gives hard, crack-prone martensite; if repair is unavoidable, preheat 250–300 °C and temper immediately after.

Can 1.4123 be formed, bent or molded?

Hot forge 1100–850 °C with slow cooling and immediate anneal; cold forming is limited to light straightening or thread rolling in the spheroidized state.

What surface finishes work on 1.4123?

Passivate per AMS 2700 or ASTM A967 after grinding; the clean remelted structure polishes to a mirror finish and accepts PVD (TiN, DLC) or plasma nitriding below the tempering temperature.

1.4123 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.

ElementSpec limit (wt %)Nominal
C0.35 – 0.450.4
Si≤ 0.60.3
Mn≤ 0.60.3
P≤ 0.03—
Slow S for rolling-contact fatigue cleanliness≤ 0.01—
Cr15 – 1615.5
Mo1.5 – 21.8
V0.2 – 0.40.3
Npressurized/solution nitrogen, raises PREN and hardness retention0.15 – 0.250.2
Niresidual≤ 0.5—
Febalance—

1.4123 +QT-HT — frequently asked

What is 1.4123 +QT-HT used for?

1.4123 +QT-HT is typically used for corrosion-resistant rolling bearings, aerospace bearings, precision instrument bearings and valve seats. In short: corrosion-resistant bearing steel; N-alloyed, better than 440C; high hardness retention.

What is the yield strength of 1.4123 +QT-HT?

1.4123 +QT-HT has a typical yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,100 MPa (305 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.

Is 1.4123 +QT-HT easy to machine?

Not especially — machinability is rated not recommended (8/100, worse than 100% of stainless steel grades). Machine in the annealed/spheroidized condition with rigid setups, sharp coated carbide and generous coolant; after hardening only grinding, honing, EDM or hard turning with CBN is practical.

Can 1.4123 +QT-HT be welded?

Not readily — weldability is rated poor (20/100). Essentially not weldable for structural use — high carbon plus nitrogen gives hard, crack-prone martensite; if repair is unavoidable, preheat 250–300 °C and temper immediately after.

What surface finishes work on 1.4123 +QT-HT?

Passivate per AMS 2700 or ASTM A967 after grinding; the clean remelted structure polishes to a mirror finish and accepts PVD (TiN, DLC) or plasma nitriding below the tempering temperature.

Can 1.4123 +QT-HT be formed, bent or molded?

Hot forge 1100–850 °C with slow cooling and immediate anneal; cold forming is limited to light straightening or thread rolling in the spheroidized state.

What is the maximum service temperature of 1.4123 +QT-HT?

1.4123 +QT-HT is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.

Sources

  1. EN 10088-3 Stainless steels — Technical delivery conditions for semi-finished products, bars, rods — CEN (2014)
  2. XD15NW nitrogen-alloyed martensitic stainless bearing steel — Aubert & Duval (2020)
  3. ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
  4. ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)

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.