Chassis steel with guaranteed hole expansion of at least 60%

For economical, lightweight, high-strength chassis parts

Hot-rolled bainitic chassis steel CH-W^® is ideal for complex, cold-formed chassis parts with high hole expansion requirements.

As a further development of our proven complex-phase steels, the new bainitic chassis steel CH-W^® offers significantly improved formability with otherwise comparable properties. CH-W^® permits than hitherto larger openings with tighter flange radii.

The chassis grade is also characterized by very good surfaces. The CH-W^® is available uncoated and hot-dip galvanized.

Advantages at a glance:

Guaranteed hole expansion capacity of at least 60%
Improved elongation
No graining on the surface
Very good MAG weldability without hardening
Good fatigue strength

Bainitic chassis steel CH-W® is ideal for use in the chassis. — Bainitic chassis steel CH-W^® is ideal for use in the chassis.

With its property profile, the bainitic chassis steel CH-W^® is particularly suitable for complex chassis components such as single-skin control arm, spring plates and similarly demanding parts.

Hot-rolled bainitic chassis steel

Steel grade	Reference grade VDA 239-100	Reference grade DIN EN 10338, DIN EN10346	Thickness from _ to in mm	Width from _ to in mm
CH-W^® 660Y760T-UC	HR660Y760T-CP	HDT760C	1.80 – 5.00	940 – 1,360
CH-W^® 660Y760T-GI/+Z	HR660Y760T-CP-GI	HDT760C+Z	1.80 – 3.00	970 – 1,330

Mechanical properties

Steel grade	Yield strength R_p0.2 [MPa]	Tensile strength R_m [MPa]	Elongation A [%] min.	A₈₀ [%] min.	Hole expansion Thickness [mm]	λ [%] min.
CH-W^® 660Y760T	660 – 820	760 – 960	14	12	1.80 – 4.20	60
CH-W^® 660Y760T	660 – 820	760 – 960	14	12	4.21 – 5.00	50

Test direction in rolling direction.

Notes on applications and processing

Material characteristics

Microstructure

Due to its selected chemical composition and the special rolling process, the bainitic chassis steel has a very fine microstructure. The desired properties of the steel are created by the specific microstructure with nanoprecipitations. The low Si content guarantees a flawless surface.

Microstructure of CH-W^®

Forming

Hot-rolled bainitic chassis steel is often used in the vehicle chassis area. It offers high resistance to local necking thanks to favorable work hardening behavior. Due to its extremely fine and homogeneous microstructure, CH-W^® steel also exhibit guaranteed hole expansion properties of at least 60% to ISO 16630. Furthermore bainitic chassis steel provides a favorable bending behavior, bending angles of well over 130° (to VDA 238-100) are typically possible.

Joining

Bainitic chassis steel is very suitable for welding both same-grade joints and hybrid joints with other common steel grades. The precondition is welding parameters matched to the material. Test results in accordance with SEP 1220-x are available and attest CH-W^® good ability to join in any joining process. Of particular note are the excellent results of the typically even and fine-flaked MAG welding seams without cracking tendency or significant hardening. Consequently, the high demands placed on the fatigue strength of the seams are fulfilled.

Fatigue strength

The bainitic chassis steel CH-W^® 660Y760T displays a comparably good fatigue strength like standard chassis grades.

Stress-strain curve of CH-W^® 660Y760T compared to HR660Y760T-CP and S700MC