Recknagel - Steel Glossary: Hardox 600

Chemical Composition %

	C^*)	Si^*)	Mn^*)	P^*)	S^*)	Cr^*)	Ni^*)	Mo^*)	B^*)
max.	0.47	0.70	1.40	0.015	0.01	1.20	2.50	0.70	0.005

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

Hardox 600 is an extra-hard and tough wear-resistant steel for extreme wear conditions.

Hardness
(Guaranteed Value)

HBW 570 - 640 (Thicknesses above 51mm: 550 - 640 HBW). The plates are through-hardened to at least 90% of the guaranteed minimum surface hardness.

Heat Treatment

Hardox 600 is not intended for further heat treatment.
The properties present in the delivery condition cannot be maintained if the steel is exposed to temperatures above 250°C.

Delivery Condition

Hardened and tempered

Surface

In accordance with EN 10163-2 Class A, Subclass 1

Flatness

Tolerances according to Hardox flatness guarantees, Class E, which are stricter than the tolerances of DIN EN 10029, Class N.

	Thickness Ranges [mm]
	6.0 - 7.9	8.0 - 24.9	25.0 - 39.9	40.0 - 65.0
Class E	11mm	10mm	9mm	8mm

The values represent flatness, measured in mm over a 1-meter ruler.

Weldability

	Carbon Equivalent CET [CEV]
Thickness	6.0 - 35.0	35.1 - 65.0
Max.	0.57 (0.69)	0.61 (0.87)
Typ.	0.55 (0.66)	0.59 (0.85)

Ultrasonic Testing

Each sheet is extensively tested, certificates 3.1 are available, and 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 Inspection²⁾

According to EN 10 160	Edge Zone Width²⁾ [mm]	Minimum Length of Defect to Consider [mm]	Maximum Length of Defect Allowed [mm]	Maximum Allowed Defect Area [mm²]	Maximum Number of Defects per Meter Length	Corresponding Steel-Iron Delivery Conditions
E₀	50 - 100	50	100	2,000	6	-
E₁	50 - 100	25	50	1,000	5	SEL 072 Klasse 3
E₂	50 - 100	20	40	500	4	SEL 072 Klasse 2
E₃	50 - 100	15	30	100	3	SEL 072 Klasse 1
E₄	50 - 100	10	20	50	2	-

¹⁾ The inspection can be ordered and performed as a comprehensive inspection, for example, E₁S₁ or E₂S ₂, or as edge zone-only or surface-only inspection, 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 tighter 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.

		6.0 - 7.9	8.0 - 24.9	25.0 - 39.9	40.0 - 65.0
Hardox 600	Quarto-Sheet Class E Measuring length 1,000mm	11mm	10mm	9mm	8mm

Sheets made of Hardox are equipped with a standard rust protection coating and an individual sheet identification.

Welding Instructions

Hardox combines unique wear resistance with excellent weldability. All common welding methods can be used for connections between Hardox and 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 material, 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 from 0.7 to 6.0 mm allows materials with strengths of 900 MPa. Low-alloyed materials result in higher hardness, which benefits wear resistance. If the wear resistance of the weld is decisive, the addition of a wear-resistant overlay can be considered.

Welding Process	DIN EN ISO Classification
MAG / Solid Wire	EN ISO 14341-A- G 38x EN ISO 14341-A- G 42x
MAG / Flux Cored Wire	EN ISO 17632-A- T 42xH5 EN ISO 17632-A- T 46xH5
MAG / Metal Powder Flux Cored Wire	EN ISO 17632-A- T 42xH5 EN ISO 17632-A- T 46xH5
MMA / Covered Electrode	EN ISO 2560-A E 42xH5 EN ISO 2560-A E 46xH5
SAW / 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 additions

Stainless welding additives can be used for all Hardox steels, and they are preferred for Toolox 44. 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 Process	DIN EN ISO Classification
MAG / Solid Wire	EN ISO 14343-A: B 18 8 Mn/ EN ISO 14343-B: SS307
MAG / Flux Cored Wire	EN ISO 17633-A: T 18 8 Mn/ EN ISO 17633-B: TS307
MAG / Metal Powder Flux Cored Wire	EN ISO 17633-A: T 18 8 Mn/ EN ISO 17633-B: TS307
MMA / Covered Electrode	EN ISO 3581-A: 18 8 Mn/ EN ISO 3581-B: 307
SAW Submerged Arc Welding	EN ISO 14343-A: B 18 8 Mn/ EN ISO 14343-B: SS307
TIG	EN ISO 14343-A: W 18 8 Mn/ EN ISO 14343-B: SS307

austenitic additives

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

Recommended Maximum Heat Input

The specific heat input varies depending on the different welding processes. The thermal efficiency k is about 0.8 for MAG welding and MMA welding, about 1.0 for UP welding, and 0.6 for TIG welding. The heat input is determined by voltage (U [V]), current (I [A]), and feed rate (v [mm/min]). The graph shows the recommendations for maximum values. A very low heat input may negatively affect the notch toughness of the weld, while extremely high values result in an enlarged heat-affected zone with altered mechanical properties. Moderately low values improve wear resistance, distortion, toughness, and strength.

Hydrogen Content

The risk of hydrogen embrittlement is present for steels, and it can be mitigated by the following measures:

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

Preheating

Preheating is crucial for achieving a good weld joint. The recommended preheating temperatures for low-alloy or non-alloy materials are shown in the following table.
Please note:

For plates of different thicknesses, use the temperature for the thicker plate.
For different plate materials, use the temperature of the material with the higher preheating temperature.
For heat input below 1.7 kJ/mm, increase the temperature by 25°C; for heat input below 1.0 kJ/mm, consult the WearCalc program.
In case of low ambient temperatures or high humidity, increase the temperature by 25°C.
For DV or DY welds, start the first run outside the center of the plate.

Recommended Minimum Working Temperature

The maximum temperatures after welding one pass and before adding another pass are:

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

Primed Plates

Due to the low zinc content, it is possible to weld directly on the Hardox primer. However, it is advantageous to remove the primer with a wire brush to avoid porosities. Good ventilation is important for the health of the welder and individuals 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 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