According to the H-R diagram, a red star is 3000K, a yellow star is 6000K and a white star 10000K.
But a hot metal appears red at 1000K, yellow at 1500K and white at 2000K.(approximately)
Why is there a difference in color temperature?
[Physics] An object glows red at around 1000K while a red star is around 3000K. What causes this misalignment in spectra
electromagnetic-radiationtemperaturethermal-radiationvision
Related Solutions
You would be unlikely to see green. The problem is that in order to see green, you would need the spectrum of emitted light to peak at green and have relatively little contribution from other frequencies. This, for example, is the reason you do not see green stars (There is a cute Feynman story about this). An explanation of color temperature is given on wikipedia. Here is the path a black body takes with temperature increase--a Planckian locus diagram .
Just to add to Vineet's answer. Wien's displacement law only tells you the peak wavelength of a hot object's spectrum. The actual emmission spectra is a broad function and so a hot object will emit both longer and shorter wavelengths.
Remember also that a hot object will emit overall more power, and finally you have to include your eye's sensitivity to various wavelengths.
So a piece of hot metal will appear white because although it's peak emmission will be in the infrared it is still emitting a lot of power at shorter wavlengths and your eye is more sensitive to blue than red.
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Best Answer
An object at 1000K glows red because that is basically dominating the radiation that it is emitting that we can see. Most of the radiation it emits emerges in the infrared part of the spectrum to which our eyes are not sensitive.
Your edited question asks about the appearance of hot metals. The chart below is an example of a "colour-temperature" chart for steel (from here) and roughly matches the second sentence of your question.
Hot metals do approximate to blackbodies, but to get some idea of what colour a relatively cold (i.e. $<2000$ K) black body will look like, you need to convolve the blackbody flux distribution with the response of the eye. In the case of objects at around 1000 K, the peak of the blackbody function, in terms of wavelength, is at around 3 microns - way below where our eyes are sensitive. This means at these temperatures your eyes are only sensitive to the short wavelength Wien tail of the blackbody distribution. As the temperature increases, the Wien tail in the visible part of the spectrum increases and light at bluer wavelengths become bright enough to excite a response in the eye. The radiation must always be weighted so that there is more red light than blue, but because the eye's response peaks at shorter wavelengths, I assume that when a metal reaches 1500 K or so, there is enough yellow light in the Wien tail to stimulate the eye into perceiving a yellow colour.
Stars are hotter. At 3000 K the peak of the blackbody distribution is just redward of what we can perceive. The stars emit light across the whole of the visible range, but weighted towards the red. Given the above discussion about metals we might expect such stars to appear almost white. A number of people have gone to the trouble of working out what colours stars should be, as viewed by the eye. In fact, stars are not strongly coloured at all, because at temperatures of 3000K and above, the black-body(ish) radiation from stars covers wavelengths across the entire range of the eye's sensitivity. The descriptions of "red star" and "yellow star" really refer to where the peak of the blackbody flux distribution lies, rather than their true visible appearance.