Looking at a Comparison of As-Rolled and Normalized Properties

While medium carbon bar steels are often used in the as-hot rolled condition, some applications call for normalizing the hot rolled product. Normalizing consists of re-austenitizing the steel followed by ambient air cooling. This often results in improvements in ductility and notch toughness.

As part of the development of the AISI bar steel fatigue database, the properties of SAE 1541 steel were examined in the hot rolled and normalized conditions. The hot rolled bars were given a slight cold sizing treatment; the normalized bars were subjected to austenitizing at 900°C and air cooled.

The mechanical properties obtained for the two conditions were as follows:

Condition

Yield
Strength MPa

Tensile
Strength MPA

Red. in Area, %

BHN

As-Rolled
(Cold Sized)

461.0

905.5

41.7

195

Normalized

471.2

783.2

55.1

180

Normalizing resulted in a slight increase in yield strength, a reduction in tensile strength and hardness, and improved ductility. Both the as-rolled and normalized conditions exhibited ferrite-pearlite microstructures. The strain-controlled fatigue properties determined for both conditions are shown in Figure 1.


Figure 1

It can be seen that Iteration No. 1 gives the fatigue results after normalizing, and Iteration No. 2 shows the fatigue properties in the as-rolled condition. The curves drawn through the data points for each iteration were calculated from their respective strain-life equation. As can be seen, the fatigue properties for both conditions are very similar.

In the case of the long life regime, the curves show the as-rolled SAE 1541 as having somewhat better fatigue performance than the normalized SAE 1541. A calculation of the fatigue strengths at one million cycles from the strain life equations results in values of 312 MPa for the as-rolled condition, and 260 MPa for the normalized condition  This might be expected, since the as-rolled condition exhibited slightly higher tensile strength and hardness.

However, as can be seen from the actual data points, the difference in the fatigue performance between the two conditions is quite modest. Thus application considerations should focus primarily on mechanical property requirements, with fatigue performance being a secondary consideration.

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2 Responses to Looking at a Comparison of As-Rolled and Normalized Properties

  1. Superb web site. Plenty of valuable information below.. sup7 spring steel bar Now i am mailing this to a few associates ans moreover revealing with delicious. And of course, thank you so much in the perspiration!

  2. I had no idea that there was a difference between hot or cold rolled steel. Thanks for explaining the benefits and the little things that make the differences of both. Cold sounds like it’s a great option since it improves the toughness.

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