Metallurgical Temp Converter

Convert temperatures between °C, °F, K, and °R with color reference for steel heat treatment.

Converter

How to Use

  1. 1
    Enter the Temperature Value

    Type the numeric temperature in the input field and select the source scale: Celsius (°C), Fahrenheit (°F), or Kelvin (K).

  2. 2
    Read Equivalents in All Scales

    All three equivalent temperatures are displayed instantly, along with material-relevant reference points such as the melting range of common alloys near the entered temperature.

  3. 3
    Use the Alloy Melting Point Lookup

    Optionally search for an alloy by name to display its solidus and liquidus temperatures on the scale, helping you assess processing temperature margins.

About

Temperature is perhaps the most critical process variable in metallurgy and alloy engineering. Every major processing operation — casting, rolling, forging, heat treatment, welding, brazing — is defined by a temperature range, and every material's properties are temperature-dependent across the service range. The difference between Celsius, Fahrenheit, and Kelvin scales is a persistent source of confusion between American and international specifications.

The AlloyFYI Temperature Converter integrates material-relevant reference temperatures — phase transformation points, embrittlement ranges, standard heat treatment windows — directly alongside the numerical scale conversion, giving the converted temperature engineering context rather than just a number. The integrated melting point lookup supports casting and brazing process planning, helping engineers verify that a process temperature maintains the required superheat margin above the liquidus or remains safely below the solidus for solid-state forming operations.

FAQ

Why do materials engineers use Kelvin rather than Celsius?
Thermodynamic calculations — including Gibbs free energy, equilibrium constants for phase transformations, diffusion coefficients, and thermal radiation — require absolute temperature (Kelvin) because these relationships are physically meaningful only on a scale where zero corresponds to the absence of thermal energy (absolute zero). Converting °C to K is simply K = °C + 273.15. Celsius is convenient for everyday temperature specification in process parameters and service conditions, but any calculation involving activation energies, diffusion, or thermodynamic potentials must use Kelvin to give physically correct results.
What are the melting ranges of common engineering alloys?
Representative melting ranges: carbon steel solidus/liquidus 1,425–1,540°C (2,597–2,804°F); 304 stainless steel 1,400–1,455°C (2,552–2,651°F); 6061 aluminum 582–652°C (1,080–1,206°F); C110 copper 1,083°C (1,981°F); Grade 5 titanium (Ti-6Al-4V) 1,604–1,660°C (2,919–3,020°F); Inconel 718 1,260–1,336°C (2,300–2,437°F). These values are critical for setting casting temperatures, hot working temperature ranges, and brazing parameters.
What is the significance of the eutectoid temperature in steel heat treatment?
The eutectoid temperature for plain carbon steel is approximately 727°C (1,341°F), the temperature at which the eutectoid composition (0.77 wt% C) transforms from austenite (γ) to pearlite (ferrite + cementite) on slow cooling, or from pearlite to austenite on heating (the A₁ critical temperature). To austenitize a hypoeutectoid steel for hardening, it must be heated above the A₃ temperature (complete transformation to austenite), typically 30–50°C above the equilibrium critical temperature to ensure full carbon dissolution, before quenching to produce martensite.
How does temperature affect the properties of stainless steels during service?
Austenitic stainless steels experience sensitization (chromium carbide precipitation at grain boundaries, depleting corrosion-resistant chromium) when held in the 425–870°C (800–1,600°F) range, compromising intergranular corrosion resistance. Sigma phase precipitation in the 650–950°C range in duplex and high-chromium austenitic grades embrittles the steel. Below approximately −100°C, austenitic stainless steels retain excellent toughness (unlike ferritic steels which suffer ductile-to-brittle transition), making them preferred for cryogenic vessels. These temperature-driven microstructural changes govern material selection and operating temperature limits.
What are pyrometric temperature measurement methods used in heat treatment?
Thermocouples (Type K: −200 to 1,260°C; Type S/R: 0 to 1,600°C; Type B: 50 to 1,800°C) are the workhorses of industrial temperature measurement in heat treatment furnaces. Radiation pyrometers (non-contact infrared) measure surface temperature from emitted thermal radiation, requiring knowledge of the material's emissivity, which varies significantly between polished and oxidized metal surfaces. ASTM E220 covers thermocouple calibration, and AMS 2750 (the NADCAP-required aerospace pyrometry standard) specifies instrument accuracy requirements, calibration frequency, and thermocouple placement for hardening, annealing, and stress relief furnace processes.
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