Durabor® 30MnB5 – Premium Quenchable Boron Steel for Superior Hardness and Uniform Microstructure

Quenchable boron steel represent a breakthrough in heat treatment technology. This steel uses boron as a hardening agent. The melting and refining process, together with thermomechanical treatment by controlled hot rolling, allow ArcelorMittal quenchable boron steel to attain a remarkable degree of hardness and a very uniform microstructure, resulting in excellent mechanical loading performance after heat treatment of the finished part.

Properties

Dimension

Property	Value
Dimensions	Please feel free to check the figure on the right side of the material page for more details.

Mechanical

Property	Value	Comment
Elongation	8 %	Quenched \| 6 mm specimen in the rolling direction
	25 %	Delivery condition \| 6 mm specimen in the rolling direction
Hardness, Rockwell C	50 [-]	Quenched \| 6 mm specimen in the rolling direction
Tensile strength	660 MPa	Delivery condition \| 6 mm specimen in the rolling direction
	1700 MPa	Quenched \| 6 mm specimen in the rolling direction
Yield strength	440 MPa	Delivery condition \| 6 mm specimen in the rolling direction
	1200 MPa	Quenched \| 6 mm specimen in the rolling direction

Chemical properties

Property	Value	Comment
Aluminium	0.02 %	min.
Boron	0.001 - 0.004 %
Carbon	0.27 - 0.33 %
Manganese	1.15 - 1.45 %
Phosphorus	0.025 %	max.
Silicon	0.2 - 0.3 %
Sulfur	0.004 %	max.
Titanium	0.02 - 0.05 %

Technological properties

Property
Application areas	Quenchable boron steel is used in applications requiring good wear resistant properties. The main applications for these steel grades after heat treatment are agricultural machinery (discs, plough shares), machinery for public works and mining, cutting equipment, tubes for automotive safety parts etc. A popular application for untreated steel is concrete mixer drums.
Chemical composition	This grade receives a globularisation treatment of the manganese sulphides. The efficiency of boron is ensured by the addition of elements that bind nitrogen.
Delivery condtion	In spite of their moderate hardness and mechanical properties, boron grades exhibit remarkably good abrasion resistance in their delivery condition, thanks to their composite microstructure consisting of a hard pearlite phase embedded in ferrite. They are therefore very cost-effective solutions for applications requiring good abrasion resistance.
Heat Treatment	The recommended austenitising temperature is 830°C to 850°C. The temperature at the beginning of the quenching process (i.e. at the maximum cooling rate) is 730°C. The TRC diagrams are available on request. After heat treatment Its extreme hardness after heat treatment makes this grade particularly suitable for applications requiring high wear/abrasion resistance. Its use allows significant weight saving (up to 50% compared with an HSLA grade) in structural and automotive components. The specific advantage of ArcelorMittal quenchable boron steels is their suitability for water quenching, making the process more environmentally friendly (less effluent treatment) than that used for conventional carbon steels. Their hardening performance is excellent with both liquid and gas quenching. The choice of grade will depend on: The required hardness of the finished part The abrasion resistance required The severity of the forming process envisaged
Other	The fatigue resistance of ArcelorMittal's boron quenchable steels is between 40 and 60% higher than S355MC AM FCE low alloy grade. It can be reduced by over 30% if total decarburisation is carried out.
Processing methods	Forming This grade can be hot or cold formed.
Surface condition	This boron grade is available in A unexposed surface quality only.

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