Section E - Repair & maintenance types
This section includes a diverse range of consumables for many repair and maintenance applications, including cast iron, dissimilar welding and hardfacing. There is also a selection of non-ferrous solid wires for copper base alloys. The final selection of products covers mild steel TIG wires and some specialist mild steel electrodes.
	Consumables for welding Cast Irons
The welding of cast irons has been notoriously called a 'black-art'. Individual castings of equivalent types can vary in response to welding, and so do the details of procedure considered critical by experienced practitioners. Most castings are produced to net shape, so welding is usually for repair and maintenance rather than fabrication. Structural load-bearing use is typically compressive, not critically tensile.
The two commonest types of cast iron have around 3%C and 2%Si. Flake graphite grey iron varies in quality and impurity content, with relatively low strength and ductility. Spheroidal graphite (SG), nodular or ductile iron is treated with magnesium, has fewer impurities, superior mechanical properties, and more reliable weldability.
Electrodes based on pure nickel and nickel-iron alloys are most widely used. Electrode flux coverings are of basic type plus graphite to give a weld deposit deoxidised and saturated with carbon. This mimics some of the characteristics of cast iron but is non-hardenable and easily machined. Recommended welding techniques are given on relevant data sheets.
Another group, high alloy austenitic irons (Ni-Resist types) are also produced in flake and SG grades. Electrodes of the NiFe type are used because matching weld metal is too hard. Preheat of 300-350°C is required for the flake graphite grades, but for the SG grades buttering at low temperatures is preferred to avoid HAZ hot cracking.
Martensitic cast iron (Ni-Hard types) and the various white irons are generally considered too crack-sensitive or brittle to be welded satisfactorily.

Data Sheet	Alloy	Process	Product	Specifications
				AWS	BS EN / BS EN ISO
E-10	Ni Cast Iron	MMA	CI Soft Flow Ni	ENi-CI	E C Ni-CI 1
		TIG/MIG	Nickel 2Ti	ERNi-1	S Ni 20 6 1
E-11	NiFe Cast Iron	MMA	CI Special Cast NiFe	ENiFe-CI	E C NiFe-CI 1
			CI Met NiFe	ENiFe-CI	E C NiFe-CI 1
		MIG	55NiFe	--	S C NiFe-1

Palm House at Kew Gardens. Repaired with Cast Iron MMA

Dissimilar welding consumables

Transition welds between dissimilar materials are often necessary, requiring weld metal compatible with dilution by these materials to provide satisfactory service properties. Weld metal dissimilar to the base material may also enable a safer or simplified welding procedure to be used, such as in armour welding. Dissimilar weld metal is almost always applied when buttering, cladding or surfacing. The metallurgy of dissimilar metal welds is a large and complex subject, considering the variety of possible combinations of industrial alloys and service conditions as a whole.

Data Sheet	Alloy	Process	Product	Specifications
				AWS	BS EN / EN ISO
E-20	Armour plate	MMA	Armet 1	E308Mo-16	E 20 10 3 R
		FCW	Supercore 20.9.3	E308MoT0-1/4	T 20 10 3 R
			Supercore 20.9.3P	E308MoT1-1/4	T 20 10 3 P
E-21	307	MMA	Metmax 307R	E307-26	E 18 9 Mn Mo R
			19.9.6Mn	(E307-16)	(E18 8 Mn R)
		MIG	19.9.6Mn	(ER307)	18 8 Mn
E-22	312	MMA	29.9 Super R	(E312-17)	E 29 9 R
		TIG/MIG/SAW	312S94	ER312	29 9

	Metrode Armet 1 and Supercore 20.9.3 used in the fabrication of tanks and armoured vehicles and approved by the MOD in the UK. The Challenger Armoured Repair & Recovery Vehicle (CRARRV) AS90 Braveheart self propelled howitzer Challenger 2 main battle tank

	Copper and Copper Alloy wires
The non-ferrous alloys in the following section are primarily used for joining equivalent base materials, although many are also used for surfacing. There are no MMA electrodes in this section; the gas shielded solid wire TIG/MIG processes are preferred for high integrity work. Note the cupronickel consumables are in section D, details can be found on data sheet D-70.

Data Sheet	Alloy	Process	Product	Specifications
				AWS	BS EN / EN ISO
E-30	Copper	TIG/MIG	100Cu	ERCu	S Cu 1898/CuSn1
E-31	Copper Silicon	TIG	97CuSi	ERCuSi-A	S Cu 6560/CuSiMn 1
E-33	Bronze	TIG	92CuSn	(ERCuSn-C)	S Cu 5210/CuSn8P
E-36	Al Bronze	TIG/MIG	90CuAl	ERCuAl-A2	S Cu 6180/CuAl10Fe
E-37	Ni Al Bronze	TIG/MIG	80CuNiAl	ERCuNiAl	S Cu 6328/CuAl9Ni5Fe3Mn2

	Consumables for surfacing and hardfacing
Hardfacing is just one aspect of surfacing in general. In principle, almost any electrode with the desired properties can be chosen to modify the working surface of a base metal for improved service life or performance.
Electrodes in this section are types recognised for their value to combat many forms of destructive wear found in different working environments. Flexibility of electrode design allows overlay compositions unique to this process, or similar to base materials for tool and component repairs.
The most suitable type for a given application can lead to conflicting choices. Often this is based (perhaps with good reason) on previous experience, or even the simple judgement of 'harder is better'. This is rarely strictly true because actual performance usually involves a combination of factors. These include response of the particular weld composition and microstructure to size and density of abrasive (when present), impact, corrosion, friction and heat. Weld metal cracking, the need for buffer layers and alloy cost are also relevant. Brief details are given to help assess some of these questions.
Martensitic types offer the lowest cost-hardness ratio. These transformable steels air-harden roughly in proportion to carbon and alloy level. Higher alloys include high speed and hot-work tool steels which may be heat treated if used for tool repairs. If critical, cracking in martensitic types is easily controlled with preheat. Lower hardness types are used for extensive build-up or intermediate layers.
Chromium carbide types resist extreme grinding abrasion, increasing with volume and type of carbides in the high alloy matrix. With almost no ductility or response to heat treatment, build-up is limited by stress cracking, although this may not be detrimental to service performance.
Cobalt base types are costly but excel at high temperatures in combination with aggressive wear or corrosion. Increasing preheat with hardness and weld thickness is needed for the alloy order 6, 12 and 1, to control stress cracking but none for the more ductile alloy 8, which also resists thermal shock and work-hardens strongly.
'Hadfield' non-stainless austenitic 13%Mn steels, show unique resistance to gouging and impact or coarse particle abrasion. Others such as type 307 (data sheet E-21) could be classed as work-hardening types for ambient temperatures.
Buffer or build-up layers are usually intermediate in alloying between base and capping layers. Hardness of a martensitic type will be reduced if deposited on a stainless buffer (data sheets B-50, B-51, E-20, E-21 and E-22), but would be ideal beneath chromium carbide and work-hardening types (and generally optional for cobalt base).

Data Sheet	Alloy	Process	Product	Specifications
				AWS	BS EN / BS EN ISO
E-45	C	MMA	Nimrod C	(ENiCrMo-5)	ENi2
			Nimax C	(ENiCrMo-5)	ENi2
E-50	350	MMA	Methard 350	--	(EFe1)
		FCW	Hardcore 350	--	TFe1
E-51	650	MMA	Methard 650	--	(EFe2)
			Methard 650R	--	(EFe2)
		FCW	Hardcore 650	--	TFe2
E-53	Tool steel	MMA	Methard 750TS	EFe5-B	EFe4
E-55	850/950	MMA	Methard 850	--	EFe14
			Methard 950	--	EFe14
		FCW	Hardcore 850	--	TFe15
			Hardcore 950	--	TFe15
E-58	1050	MMA	Methard 1050	--	EFe16
E-60	13%Mn	MMA	Workhard 13Mn	EFeMn-B	EFe9
E-65	Cobalt	MMA	Cobstel 6	ECoCr-A	(ECo2)
E-66	Cobalt	MMA	Cobstel 8	ECoCr-E	ECo1

	Specialist range of mild steel consumables
The mild steel TIG wires and flux cored wire are used for general purpose mild steel fabrication, the other consumables in this section have specialised applications. Ultramild is an E6018 type depositing soft and ductile low hydrogen weld metal mainly for buffer layers. Nilsil is a modified E6013 type giving very low silicon weld metal for welding galvanising baths.

Data Sheet	Alloy	Process	Product	Specifications
				AWS	BS EN / BS EN ISO
E-70	Mild steel	TIG	ER70S-2	ER70S-2	A15
			ER70S-3	ER70S-3	(A17)
			ER70S-6	ER70S-6	A18
		FCW	Metcore DWA50	E71T-1	T 422 PM1
E-71	Low strength mild steel	MMA	Ultramild	E6018	--
E-72	Low silicon	MMA	Nilsil	--	--

Pepsi Max Big One roller coaster, Blackpool, Fabricated with Metrode DWA50 flux cored wire