Welding of NM360 Steel and 16Mn Steel
NM360 Steel
NM360 steel is a low alloy, high strength wear resistant steel constructed with 0.34% carbon, 1.20% chromium, 0.25% molybdenum, and 0.75% nickel. It generally used for engineering, construction and coal mining industry. The common characteristic of NM360 steel is its superior wear-resistance, high strength, and excellent toughness. The combination of these properties makes NM360 an optimum choice in a wide range of applications.
16Mn Steel
16Mn steel is a low alloy steel composed of 0.14-0.20% carbon, 0.30-0.60% manganese, and 0.45-0.75% silicon. This steel has medium strength and is often used in demanding applications such as bridges, ships, railway wagons, offshore platforms, and so on. Additionally, 16Mn steel has a lower stress corrosion cracking rate compared to other carbon steel plates due to a combination of high tensile strength and good toughness.
Weldability
NM360 and 16Mn steel generally have good weldability, which is determined by the material’s chemical compositions and acceptable welding current settings. However, it is important to note that the weldability of these two materials differ due to their distinct chemical compositions. Additionally, heat input and preheating of the base metals should be observed and changed according to the respective material data sheets.
NM360 Steel
NM360 steel has an optimal weldability with recommended parameters for welding current and electrode diameter. Preheating and interpass temperatures of the steel should be between 400 F and 600 F and must be slowly cooled in order to avoid cracking at the weld joints.
FIG 1 - NM360 Steel Weldability
16Mn Steel
The recommended welding current and electrode diameter for 16Mn steel is lower than that of NM360 steel due to its increased carbon content. The preheating and interpass temperatures of 16Mn steel must also be maintained continuously below 600 F in order to avoid any type of cracking at the weld joints.
FIG 2 - 16Mn Steel Weldability
Appropriate Welding Techniques
The common welding techniques used for the welding of NM360 and 16Mn steel are manual metal arc (MMA) welding, gas metal arc welding (GMAW), and submerged arc welding (SAW). The use of each welding method varies for different application as this allows for greater control and accuracy.
MMA Welding
MMA welding is a manual arc welding process and is one of the most widely used welding processes for the welding of NM360 and 16Mn steel. An electric arc is generated between the electrodes and the workpiece, creating heat which melts the material. The welded zone must then be cooled before the process is completed.
GMAW Welding
GMAW welding is a process that uses an arc generated by a consumable electrode wire and a MIG/MAG welding gun which melts and fuses the material together. This welding process is commonly used in manufacturing, automotive, and construction industries.
SAW Welding
SAW welding is an arc welding process in which a flux-covered electrode is continuously fed into the weld pool to form a high quality weld. This welding process is suitable for large size welds and can be automated for mass production.
Conclusion
Welding of NM360 and 16Mn steel is a popular and viable welding process in today’s industry due to the combination of mechanical and physical properties of the two materials. Although these two materials have similar weldability, they must be preheated and correctly cooled in order to avoid cracking at the weld joints. Moreover, the right welding technique must be selected according to the specifications of the application to ensure successful welds. Through adherence of welding techniques and processes, NF360 and 16Mn steel welds shall be made efficiently and with consistently good results.
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