What is the Chinese equivalent of NiCr 40/20 or Ni40Cr20?

GB Cr20Ni35. NiCr 40/20 has Ni ≥37.0%, Cr 18–22%, Si 1.8–3.0% and resistivity ≈1.05 μΩ·m; GB Cr20Ni35 has Ni 34.0–37.0%, Cr 18.0–21.0%, Si 1.00–3.00% and resistivity 1.04 μΩ·m. The two overlap across the composition range.

Is there a grade called Cr20Ni40 in the Chinese standard?

No. GB/T 1234 does not define Cr20Ni40. Some Chinese suppliers use it as a commercial name, but the standardised grade is Cr20Ni35.

Does NiCr 40/20 have an ASTM or DIN number?

No. It has no ASTM, UNS, Werkstoff or DIN designation — it is an industry trade grade.

Can NiCr 40/20 be used in a sulphur-bearing atmosphere?

No. All nickel-chromium grades are unsuitable in sulphur atmospheres. Use FeCrAl instead.

Home › Products › Nickel-Chromium Wire (NiCr Resistance Wire)

Nickel-Chromium Wire (NiCr Resistance Wire)

Short answer: we draw nickel-chromium wire in Cr20Ni80, Cr15Ni60, Cr30Ni70, Cr20Ni35 and Cr20Ni30, from φ0.03 mm to φ10 mm, bright annealed, in coils or straight lengths.

1. Grades and properties

Grade	Ni %	Cr %	ρ20 (μΩ·m)	Max service temp.	Density
Cr20Ni80	75-78	20-23	1.09 ±0.05	1200 °C / 2192 °F	8.4 g/cm³
Cr15Ni60	55-61	15-18	1.12 ±0.05	1150 °C / 2102 °F	8.2 g/cm³
Cr30Ni70	balance	28-31	1.18 ±0.05	1250 °C / 2282 °F	8.1 g/cm³
Cr20Ni35	34-37	18-21	1.04 ±0.05	1050 °C / 1922 °F	7.9 g/cm³
Cr20Ni30	30-34	18-21	1.06 ±0.05	1050 °C / 1922 °F	7.9 g/cm³

2. Available diameters

Range	Diameter (mm)	Diameter (inch)	Typical tolerance
Fine wire	0.03 - 0.10	0.0012" - 0.004"	±0.002 mm
Standard wire	0.10 - 6.0	0.004" - 0.236"	±0.02 mm (<1 mm) ±0.03 mm (1-3 mm) ±0.05 mm (>3 mm)
Heavy wire	6.0 - 10.0	0.236" - 0.394"	±0.08 mm

Straight-cut lengths available up to 3,000 mm (118"). Above 10 mm the product is technically a rod, not a wire — tell us if that is what you need and we will quote it as rod.

3. Wire weight and resistance per metre

Handy for estimating element length before you have the final drawing.

Diameter (Cr20Ni80)	Weight per metre	Resistance per metre at 20 °C
φ0.50 mm	1.65 g/m	5.55 Ω/m
φ1.00 mm	6.60 g/m	1.39 Ω/m
φ2.00 mm	26.4 g/m	0.347 Ω/m
φ3.00 mm	59.4 g/m	0.154 Ω/m
φ5.00 mm	165 g/m	0.0555 Ω/m

Cold versus hot resistance
The resistance you measure on the bench is the cold value. At working temperature Cr20Ni80 runs about 5-8 % higher (the temperature coefficient is roughly 1.0 × 10⁻⁴ /°C). If you size the element on cold resistance you will end up with slightly higher power than intended — and slightly higher element temperature. Allow for it.

4. Surface load and element temperature

This is the single parameter most often left out of an enquiry, and the one that decides whether the element lasts a year or three months.

Furnace type	Surface load (W/cm²)	Element runs above furnace by
Open air / static	1.0 - 1.8	60 - 145 °C
Box / bogie furnace	1.5 - 2.5	90 - 200 °C
Fan circulated	2.5 - 4.0	175 - 320 °C
Vacuum	1.0 - 2.0	60 - 160 °C

Work out the element temperature as furnace temperature + (surface load × 70), then check it against the grade's maximum. If the margin is under 100 °C, either drop the surface load or step up to a higher grade.

5. Where nickel-chromium is the wrong choice

Sulphur-bearing atmospheres. NiCr must not be used. Sulphur consumes the chromium oxide film and forms Ni₃S₂, which melts around 790 °C and penetrates the grain boundaries. The element thins from the inside and fails as a whole, not at a hot spot. Use FeCrAl.
Above 1250 °C. Use FeCrAl (0Cr21Al6Nb up to 1350 °C, 0Cr27Al7Mo2 up to 1400 °C).
Chlorine-bearing atmospheres. No heating alloy survives this. Isolate the element inside a radiant tube or ceramic sheath.

6. Please confirm these 4 points before ordering

Grade — if the drawing says NiCr 80/20, that is our Cr20Ni80.
Diameter with tolerance, and total length or weight
Furnace temperature and atmosphere — we will size the surface load for you.
Span between supports — over 400 mm and we will recommend a niobium-bearing grade.

Need a quotation?

Send grade, form, size with tolerance and quantity — we reply within one working day (GMT+8).

WhatsApp +86 136 6174 5686 Enquiry form

About Shanghai Xinxiang Alloy

Shanghai Xinxiang Alloy Materials Co., Ltd. was founded in 2014 and is a source manufacturer of electric heating alloys and nickel-based precision alloys. Production base in Taixing, Jiangsu, approximately 20,000 m², 48+ pieces of melting, forging, rolling, drawing, heat-treatment and testing equipment, 200+ staff, annual capacity about 7,500 tonnes.

Contact: Tel +86 136 6174 5686 / +86 21 6911 6339 | Email shryhjcl@126.com

Grade cross-references are commercial equivalents, not a guarantee of interchangeability. Final acceptance is subject to the composition sheet agreed at order.