Recknagel - Steel Glossary: Hardox 450

Chemical Composition %

		C^*)	Si^*)	Mn^*)	P^*)	S^*)	Cr^*)	Ni^*)	Mo^*)	B^*)
Cold-rolled steel	max.	0.18	0.25	1.30	0.015	0.004	0.10	0.10	0.04	0.003
Hot-rolled steel & Quarto-Sheet	max.	0.26	0.70	1.60	0.025	0.010	1.40	1.50	0.60	0.005

The steel is a fine-grain steel. ^*) Intended alloying elements

Hardox 450 is a hardened wear-resistant steel used for various applications. It can be formed by bending and can be welded easily.

Hardness
(Guaranteed Value)

HBW 425-475 (Quarto-Sheet 3.2 - 80.0 mm Thickness)

Impact Toughness
(Guaranteed Value)

Testing Temperature
-40°C

Charpy V-notch Impact Toughness
in Longitudinal Direction, minimum 50 J

Yield Strength
(Typical Value, not guaranteed)

Approx. 1,250 MPa

Delivery Condition

Hardened and Tempered

Heat Treatment

Hardox 450 is not intended for further heat treatment. The properties cannot be maintained if the steel is exposed to temperatures above 250°C. Note: For applications at higher temperatures up to 590°C, we recommend Toolox 44.

Surface

According to EN 10163-2 Class A, Subclass 1

Flatness

Tolerances according to Hardox Flatness Guarantee Class D for Quarto-Sheet, stricter than EN 10029. For Hot-rolled Strip according to Hardox Flatness Guarantee Class A, tighter than EN 10051 , and for Cold-rolled Strip according to Hardox Flatness Guarantee Class B.

	Thickness Ranges [mm]
	0.7 - 2.1	2.0 - 8.0	3.2 - 3.9	4.0 - 4.9	5.0 - 5.9	6.0 - 19.9	20.0 - 130.0
Hot-rolled Strip Class A		3mm
Cold-rolled Strip Class B	6mm
Quarto-Sheet Class D			15mm	7mm	5mm	4mm	3mm

Flatness is given in millimeters, measured on a 1-meter ruler.

Note: Toolox 44 Quarto-Sheet meets stricter flatness requirements for thicknesses of 5.0-7.9 mm = 4 mm/1,000 mm, 8 mm/2,000 mm, and 8.0-99.9 mm = 3 mm/1,000 mm, 6 mm/2,000 mm.

Weldability

	Carbon Equivalent CET (CEV)
Thickness	Cold-rolled Strip 0.7 - 2.1	Hot-rolled Strip 2.0 - 8.0	Sheet Metal 3.2 - 4.9	Sheet Metal 5.0 - 9.9	Quarto-Sheet 10.0 - 19.9	Quarto-Sheet 20.0 - 39.9	Quarto-Sheet 40.0 - 80.0	Quarto-Sheet 80.1 - 130.0
Max.	0.33 (0.44)	0.35 (0.48)	0.37 (0.48)	0.38 (0.49)	0.39 (0.52)	0.41 (0.60)	0.43 (0.74)	0.41 (0.67)
Typ.	0.31 (0.39)	0.26 (0.39)	0.29 (0.39)	0.33 (0.45)	0.36 (0.48)	0.38 (0.56)	0.38 (0.61)	0.39 (0.64)

CEV formula for calculating weldability of Hardox 400

Bending

The bendability for Quarto-Sheet corresponds to the Hardox bending guarantee Class E. Strip-Metal corresponds to the Hardox bending guarantee Class C for Cold-rolled Strip and Class B for Hot-rolled Strip . The guarantees comply with at least DIN EN 10025-6 and EN ISO 7438. The ratio of bending tool radius to sheet thickness is mentioned.

	Thickness Ranges [mm]
	0.7 - 2.9	2.0 - 3.9	4.0 - 7.9	8.0 - 14.9	15.0 - 19.9	≥ 20.0
Hot-rolled Strip Class B		⊥3.0 \|\|4.0	⊥3.0 \|\|3.5
Cold-rolled Strip Class C	⊥4.0 \|\|4.0
Quarto-Sheet Class E		⊥3.0 \|\|4.5	⊥3.0 \|\|3.5	⊥3.5 \|\|4.5	⊥3.5 \|\|4.5	⊥4.5 \|\|5.0

Ultrasonic Testing

Each sheet is thoroughly tested, and 3.1 certificates are available. The internal standards are often stricter than the industry standard.

Surface Inspection¹⁾

According to EN 10 160	Distance between parallel test lines [mm]	Minimum error area to be considered [mm²]	Maximum allowable error area [mm²]	Maximum number of local errors [number/m²]	Corresponding steel-iron delivery conditions
-	100	1,000	10,000	1	SEL 072 Class 5
S₀	100	1,000	5,000	20	-
S₁	100	100	1,000	15	SEL 072 Class 3
S₂	50	50	100	10	SEL 072 Class 2
S₃	50	20	50	10	SEL 072 Class 1

Edge zone testing²⁾

According to EN 10 160	Width of Edge Zone²⁾ [mm]	Minimum error length to be considered [mm]	Maximum allowable error length [mm]	Maximum allowable error area [mm²]	Maximum number of errors per m Length	Corresponding steel-iron delivery conditions
E₀	50 - 100	50	100	2,000	6	-
E₁	50 - 100	25	50	1,000	5	SEL 072 Class 3
E₂	50 - 100	20	40	500	4	SEL 072 Class 2
E₃	50 - 100	15	30	100	3	SEL 072 Class 1
E₄	50 - 100	10	20	50	2	-

¹⁾ The test can be ordered and conducted as a comprehensive examination, for example, E₁S₁ or E₂S₂, or as a test of only the edge zones or surface, for example, E₁ or S₁.

²⁾ The width of the edge zone in the edge zone inspection varies depending on the thickness of the sheet.

The Thickness Tolerances of the sheets according to AccuRollTech™ are narrower than DIN EN 10 029.

Nominal Thickness [mm]			Hardox Tolerance Class A [mm]		Maximum Thickness Variation in the Sheet [mm]
			min	max
	-	4.9	-0.3	+0.4	0.5
5.0	-	7.9	-0.3	+0.6	0.6
8.0	-	14.9	-0.4	+0.6	0.7
15.0	-	24.9	-0.5	+0.7	0.8
25.0	-	39.9	-0.7	+0.8	1.0
40.0	-	79.9	-0.9	+1.5	1.1
80	-		-1.0	+2.2	1.2

Hardox-Sheets have an amazing flatness.

		3.2-3.9	4.0-4.9	5.0-5.9	6.0-19.9	20.0-130.0
Hardox 450	Quarto-Sheet Class C Measurement length 1,000mm	15mm	7mm	5mm	4mm	3mm

Anti-corrosion coating on Hardox plate by SSAB

Hardox sheets come with a standard rust protection coating and individual sheet markings.

Flatness measurement on Hardox plate by SSAB

Welding Guidelines

Hardox combines unique wear resistance with excellent weldability. All common welding methods can be used for joining Hardox with weldable steels.

For best welding results, pay attention to dryness, cleanliness, and freedom from corrosion. Special attention should be given to the selection of welding materials, temperatures, heat input, and joint geometry.

Low-alloy or unalloyed welding materials with a tensile strength of 500 MPa are suitable for Hardox and Toolox. Hardox 450 in thicknesses of 0.7 – 6.0 mm allows materials with strengths of 900 MPa. Low-alloyed materials result in higher hardness, which promotes wear resistance. If the wear resistance of the weld is crucial, considering the application of a wear protection layer through overlay welding can be beneficial.

Welding Processes	DIN EN ISO-Classification
MAG / Solid wire electrode	EN ISO 14341-A- G 38x EN ISO 14341-A- G 42x
MAG / Flux-cored wire electrode	EN ISO 17632-A- T 42xH5 EN ISO 17632-A- T 46xH5
MAG / Metal powder flux-cored wire electrode	EN ISO 17632-A- T 42xH5 EN ISO 17632-A- T 46xH5
MMA / Stick electrode	EN ISO 2560-A E 42xH5 EN ISO 2560-A E 46xH5
UP / Submerged arc welding	EN ISO 14171-A- S 42x EN ISO 14171-A- S 46x
TIG / Tungsten inert gas welding	EN ISO 636-A- W 42x EN ISO 636-A- W 46x

low-alloy or unalloyed fillers

Stainless welding fillers can be used for all Hardox steels, and for Toolox 44, they should be preferred. They allow welding at 5 – 20°C without preheating, except for Hardox 600 and Hardox Extreme. SSAB recommends the following materials, which provide a yield strength of 500 MPa.

Welding Processes	DIN EN ISO-Classification
MAG / Solid wire electrode	EN ISO 14343-A: B 18 8 Mn/ EN ISO 14343-B: SS307
MAG / Flux-cored wire electrode	EN ISO 17633-A: T 18 8 Mn/ EN ISO 17633-B: TS307
MAG / Metal powder flux-cored wire electrode	EN ISO 17633-A: T 18 8 Mn/ EN ISO 17633-B: TS307
MMA / Stick electrode	EN ISO 3581-A: 18 8 Mn/ EN ISO 3581-B: 307
UP / Submerged arc welding	EN ISO 14343-A: B 18 8 Mn/ EN ISO 14343-B: SS307
TIG / Tungsten inert gas welding	EN ISO 14343-A: W 18 8 Mn/ EN ISO 14343-B: SS307

austenitic Fillers

When welding Hardox, the same gases are generally used as when welding low-alloy or non-alloy steels.

Recommended heat input max.

Heat input recommendations for Hardox 450

Heat input calculation formula for Hardox 450

The specific heat input varies with different welding processes. The thermal efficiency k is approximately 0.8 for MAG welding and MMA welding, about 1.0 for UP welding, and 0.6 for TIG welding. Heat input is determined by voltage (U [V]), current (I [A]), and wire feed speed (v [mm/min]). The graph shows the recommended maximum values. Very low heat input may negatively affect the impact toughness of the weld, while extremely high values result in an enlarged heat-affected zone, leading to changes in mechanical properties. Moderately low values improve wear resistance, reduce distortion, and enhance toughness and strength.

hydrogen content

The danger of hydrogen embrittlement exists in steels. This danger is mitigated by:

Preheating the welding area
Measuring the preheat temperature
Using welding consumables with a maximum of 5ml of water per 100g
Keeping the welding joint free from rust, grease, oil, and cold
Applying a suitable welding process
Avoiding a welding gap over 3mm at the narrowest point of the weld joint

Preheating

Preheating is extremely important for a good weld joint. The recommended preheat temperatures are shown in the following table for low-alloy or unalloyed materials.
Please note:

For sheets of different thicknesses, use the preheat temperature of the thicker sheet.
For different sheet materials, use the preheat temperature of the material with the higher value.
For heat input below 1.7kJ/mm, increase the temperature by 25°C; for heat input below 1.0kJ/mm, please refer to the WearCalc program.
In low outside temperatures or high humidity, increase the temperature by 25°C.
For DV or DY joints, start the first bead outside the center of the sheet.

Recommended Minimum Working Temperature

The maximum temperatures after welding one pass and before welding the next pass are:

Welding recommendations for Hardox 450 wear plate

Preheating with electric heating mat on Hardox 450

Electrical preheating has proven effective.
It is practical to measure the temperature on the backside.
It is recommended to wait about 2 minutes per 25mm of plate thickness.
The temperature should be reached approximately 75 - 150mm on both sides of the weld joint.

Primed Sheets

Due to the low zinc content, welding can be done directly on the Hardox primer. However, it is advantageous to remove the primer with a wire brush to avoid porosity. Good ventilation is important for the health of the welder and those nearby.

Heat Treatment

Heat treatment after welding is not recommended to preserve the mechanical properties of Hardox.

Hardness Comparison Table for Toolox and Hardox

Tensile Strength MPa	715	790	820	861	935	995	1.011	1.090	1.169	1.245	1.328	1.412	1.494	1.580	1.758	1.940	2.130
Vickers Hardness HV	205	233	243	261	289	311	317	345	373	401	429	458	485	514	569	627	682
Brinell Hardness HBW	225	250	260	275	300	320	325	350	375	400	425	450	475	500	550	600	650
Rockwell Hardness HRC	19	22.5	24	26	29	32	32.5	35.5	38	40	42.5	44.5	46.5	49	52.5	55	57.5