Improved Corrosion-Resistant Steel for Highway Bridge Construction

CHAPTER 4. PREPARATION OF CORROSION SPECIMENS

HOT ROLLING, NORMALIZING, AND TEMPERING TO ACHIEVE STRENGTH

As indicated earlier in this report, the 0.3125-inch (14.3-mm)-thick plates were saw cut into 12-inch (300-mm) lengths. To obtain material for corrosion testing, some of the pieces from each steel were reheated to 2,300 °F (1,260 °C) and hot rolled to sheets approximately 0.100 inches (2.5 mm) thick and 5 ft (1,500 mm) long. The specific pieces used for the corrosion specimens are shown in appendix A of this report. Hot rolling from 0.3125 to 0.100 inches (14.3 to 2.5 mm) produced generally good-quality steel plates (i.e., flat and with little or no cracking). This behavior was encouraging because there was some possibility that one or more of the experimental steels would exhibit poor hot workability.

The hot rolled sheets were sawcut into corrosion coupons measuring 4 inches (100 mm) by 6 inches (150 mm). Each as-rolled coupon was heated in an electric furnace under air atmosphere to 1,650 °F (900 °C), held 56 minutes, and air cooled to simulate commercial plate normalizing. The tempering temperatures used for the corrosion coupons were based on the data shown in figure 26 and are reported in table 7. The tempering time was 30 minutes.