Welding EN8 material can be a challenge for even the most experienced welder. The high carbon content of the steel makes it difficult to weld and decrease weldability. However, with the proper techniques and equipment, welding EN8 material can be done successfully.
EN8 Steel
EN8 material, EN8 steel is a popular medium carbon steel with good mechanical properties and machinability. EN8 material is suitable for the production of parts such as shafts, gears and bolts.
EN8 offers good tensile and yield strength, making it ideal for manufacturing various parts and components.
EN8 steel can be heat treated to produce a variety of different hardness levels due to its high carbon content. EN8 steel can be heat treated to achieve higher strength levels, making it ideal for use in various industries.
EN8 Steel Specification
EN8 Steel UNS Number is 080M40. This is an unclassified material according to the ASME Section IX and hence no assigned P-Number for welding.
The EN8 material specification is BS970. In BS970, EN8 is listed by number 080M40.
EN8 Equivalent Materials
There are a number of different materials that can be used as an EN8 equivalent. There are a number of equivalent materials to EN8 steel, including SAE 1045, S45C, and EN 1.1186.
These materials are all suitable for applications that require high strength and good wear resistance. They can be used in the manufacture of gears, shafts, and other mechanical components. This includes:
- AISI 1040, AISI 1045,
- ASTM A29:1038, 1040,
- EN 1.1186,
- JIS G4051: S40C, S45C.
EN8 steel Chemical Composition
EN8 steel is a popular alloy steel that offers good mechanical properties and machinability. The chemical composition of EN8 steel gives it good machinability and weldability properties.
The carbon content is typically between 0.40% and 0.50%. Other alloying elements present in small quantities include manganese, silicon and copper.
The chemical composition of EN8 steel is given in the following table.
| Element | % Composition |
|---|---|
| Carbon | 0.36- 0.40% |
| Silicon | 0.10- 0.40% |
| Manganese | 0.60- 1.00% |
| Phosphorus | 0.05% Max. |
| Sulfur | 0.05% Max. |
EN8 Steel Mechanical Properties
EN8 is a popular steel grade for many general engineering applications. It offers good tensile and yield strength, as well as good impact resistance.
EN8 Material properties depends on the heat treatment. The tensile and yield strength of EN8 material in normalized condition is 550 MPa and 280 MPa minimum respectively.
Complete mechanical properties of EN8 Steel in different heat treatment conditions are given in the below table for reference (BS970).
EN8 Material Hardness in HRC- HV
EN8 material hardness in HRC is 16 HRC maximum. the hardness of EN in HV is 149 HV to 201 HV.
EN hardness in HB is 146 HB- 207HB and given in BS 970 (Table above) standard, Table 20.
Can EN8 be Welded?
In general, EN8 can be welded. However, as with most cases, the answer is not that simple. When welding any material, it is important to consider the base material properties and the intended application of the finished product. With EN8, the challenges are its high carbon content and low melting point.
EN8 has a carbon content between 0.35-0.45%. This high carbon content makes it difficult to weld without introducing defects into the finished product. The low melting point means that heat must be carefully controlled during welding to avoid damaging the base material.
Welding EN8 can be accomplished using any of the common welding processes such as stick Welding (SMAW), TIG and MIG Welding. The key is to use lower temperatures and slower cooling rates to minimize cracking issues.
Welding Preheat Temperature for EN8 Steel
EN8 steel must be preheated before welding to avoid weld cracking. You can calculate the preheat temperature using our Online Welding Preheat Calculator.
Before welding, preheat EN8 material to 100-150°C.
SMAW Welding/ Stick Welding of EN8 Steel
SMAW or Stick Welding of EN8 material is carried out using Low hydrogen electrodes. For normalized EN8 material, welding is carried out using E7018 welding rod which gives matching weldment properties.
Welding of Quenched and tempered EN8 can also be carried out using E7018 rod if matching tensile & yield strength is not desired.
When welding high strength hardened & tempered EN8 steel for matching strength purposes, welding is carried out using E9018-G stick welding rod.
Make sure the electrodes are properly dried and baked before use. Welding with high hydrogen content electrodes, will results in Hydrogen cracking in this material.
TIG Welding of EN8 Steel
TIG Welding of EN8 Steel is carried out using ER70S-2 or ER70S-6 filler wire rods. For high strength welds of EN8, welding is carried out using ER90S-G filler wire.
MIG welding of EN8 is also carried out using ER70S-2, ER70S-6 and ER90S-G wires.
Welding EN8 to Mild Steel
Welding EN8 to Mild Steel is carried out using E7018 SMAW (stick welding electrode).
TIG and MIG welding of EN8 to Mild Steel is carried out using ER70S-2 or ER70S-6 filler wire rod.
Welding EN8 to S355
Welding EN8 to S355 is carried out using E7018 SMAW (stick welding electrode).
TIG and MIG welding of EN8 to S355 is carried out using ER70S-2 or ER70S-6 filler wire rod.
Post weld heat treatment (PWHT) of EN8 Welds
Post weld heat treatment (PWHT) of EN8 Welds shall be carried out at a temperature of 620 – 650°C. The holding time is usually kept 1 hours per inch of material thickness.
