Page 162 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

Section 5.5 Carbon and Alloy Steels

TABLE 5.3

Mechanical Properties of Selected Advanced High-strength Steels
Minimum
ultimate Minimum yield Elongation in Strain-hardening
Steel strength (MPa) strength (MPa) 50 mm (%) exponent, n
BH 210/340 340 210 36 0.18
BH 260/370 370 260 32 0.13
HSLA 350/450 450 350 25 0.14
DP 350/600 600 350 27 0.14
DP 500/800 800 500 17 0.14
DP 700/1000 1,000 700 15 0.13
TRIP 450/800 800 450 29 0.24
TRIP 400/600 600 400 30 0.23
CP 700/800 800 700 12 0.13
MART 950/1200 1,200 950 6 0.07
MART 1250/1520 1,520 1,250 5 0.065

TABLE 5.4

AISI Designations for High-strength Sheet Steel
Yield strength
psi X 103 MPa Chemical composition Deoxidation practice
35 240 S = structural quality F = killed plus sulfide inclusion control
40 275
45 310
50 350 X I low alloy
60 415 killed
70 485 W I Weathering
80 550 nonkilled
100 690 D = dual-phase
120 830
140 970
Example:
50 X F
50 >< 103 psi (350 MPa) min Low alloy Killed plus sulfide inclusion control
yield strength

the ultimate tensile strength in MPa. The types of steel are:
BH-Bake-hardenable
HSLA-High-strength low-alloy
DP-Dual-phase
TRIP-Transformation-induced plasticity
TWIP-Twinning-induced plasticity
MART-Martensitic
CP-Complex phase.
Thus, HSLA 350/450 would be a high-strength low-alloy steel with a minimum
yield strength of 35 0 MPa and a minimum ultimate tensile strength of 450 MPa.
Microalloyed Steels. These recently developed HSLA steels provide superior prop-
erties and can eliminate the need for heat treatment. They have a ferrite-pearlite
microstructure with fine dispersed particles of carbonitride. A number of microalloyed