Give the approximate temperature at which it is desirable to heat each of the following iron–carbon alloys during a full anneal heat treatment: (a) 0.20 wt% C (b) 0.60 wt% C (c) 0.76 wt% C (d) 0.95 wt% C.

To find the desired temperatures, we first need to refer to the Iron-Carbon (Fe-C) phase diagram. The diagram shows the phases of the Fe-C system at various temperature and composition combinations. For full anneal heat treatment, we want to heat the alloys to the range where austenite (γ) is the primary phase. In other words, we need to locate the phase boundary between the ferrite (α) + cementite (Fe3C) region and the austenite (γ) region.

Next, we will locate the composition of each alloy on the horizontal axis of the phase diagram and move vertically until we reach the boundary between the α+Fe3C and γ regions. We can read the temperature at this intersection as the approximate desirable heating temperature for each alloy during annealing. (a) For the alloy with 0.20 wt% C: Locate 0.20 wt% C on the horizontal axis and move vertically up until we reach the phase boundary between α+Fe3C and γ regions. The intersection occurs at approximately 727°C. Therefore, the heating temperature for this alloy during a full anneal heat treatment is around 727°C. (b) For the alloy with 0.60 wt% C: Locate 0.60 wt% C on the horizontal axis and move vertically up until we reach the phase boundary between α+Fe3C and γ regions. The intersection occurs at approximately 750°C. Therefore, the heating temperature for this alloy during a full anneal heat treatment is around 750°C. (c) For the alloy with 0.76 wt% C: Locate 0.76 wt% C on the horizontal axis and move vertically up until we reach the phase boundary between α+Fe3C and γ regions. The intersection occurs at approximately 723°C. Therefore, the heating temperature for this alloy during a full anneal heat treatment is around 723°C. (d) For the alloy with 0.95 wt% C: Locate 0.95 wt% C on the horizontal axis and move vertically up until we reach the phase boundary between α+Fe3C and γ regions. The intersection occurs at approximately 726°C. Therefore, the heating temperature for this alloy during a full anneal heat treatment is around 726°C.