Engineering Materials
In a hardening process, the hypo-eutectoid steel is

Heated from 30°C to 50°C above the upper critical temperature and then cooled in still air
Heated below or closes to the lower critical temperature and then cooled slowly
Heated from 30°C to 50°C above the upper critical temperature and then cooled suddenly in a suitable cooling medium
Heated from 30°C to 50°C above the upper critical temperature and then cooled slowly in the furnace

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Engineering Materials
Stress relaxation is the phenomenon

In which deformation tends to loosen the joint and produces a stress reduced
In which parts are not loaded
Stress reduces on increasing load
In which stress remains constant on increasing load

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