It is probably ok for what it is, but heating to non-magnetic is never enough for the hardening process. You need it to get to about 2 shades of red above non-magnetic for iron and carbon to make a well mixed homogenous solution of carbon and iron. In the case of a RR spike, you can go a little hotter than that. At any rate though, RR spikes, even the so called high carbon spikes are not really high carbon. They usually test out at around .30%, give or take a tad. They are commonly listed at .35, but very few are. Below .40 is normally considered non-hardening steel. Also with a RR spike, no temper is necessary because it will not get hard enough to need it.