Characteristics of Complex Phase (CP) Steel

CP steels characterize the transformation of steels that have very high ultimate tensile strengths. The ferrite/bainite matrix in the microstructure of CP steels consists of pearlite and retained austenite with martensite in small quantities. Retarded recrystallization or precipitation of microalloying elements such as Nb or Ti creates a very high grain refinement. The grain structure for the CP 800/1000 hot rolled steel is illustrated in Figure 1.

Photomicrograph of CP 800/1000 hot rolled steel

Figure 1. Photomicrograph of CP 800/1000 hot rolled steel

Key Characteristics of CP Steels

The yield strength of CP steels is much higher than DP steels at equal tensile strengths of 800 MPa. Good hole expansion, high residual deformation capacity, and high energy absorption are the key characteristics of CP steels. The tensile strength-elongation graph of CP steels is depicted in Figure 2.

The tensile strength-elongation graph of CP steels

Figure 2. The tensile strength-elongation graph of CP steels

The following table lists current production grades of CP steels and corresponding example automotive applications:

CP 500/800
CP 600/900
CP 680/780 Frame rails, chassis components, transverse beams
CP 750/900 B-pillar reinforcements, tunnel stiffener
CP 800/1000 Rear suspension brackets, fender beam
CP 850/1180
CP1000/1200 Rear frame rail reinforcements, rocker outer
CP1050/1470 Rocker panels, bumper beams

Download the Advanced High-Strength Steels Applications Guidelines free here, to learn more about the metallurgy, forming and joining of these new steels.

This information has been sourced, reviewed and adapted from materials provided by WorldAutoSteel (World Auto Steel).

For more information on this source, please visit WorldAutoSteel (World Auto Steel).


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