What Is Manganese Steel?

Manganese steel is a kind of high-strength steel, which is mainly used in harsh working conditions that need to withstand impact, extrusion, and material wear. The damage is mainly caused by wear and tear, and some parts are broken and deformed. Now it is generally applicable to the under guard of engines.

Manganese steel is a high-strength anti-wear steel mainly used for impact, extrusion, and material grinding.

The most important feature of high manganese steel is that under the conditions of strong impact and extrusion, the surface layer rapidly undergoes work hardening, so that it still maintains the good toughness and plasticity of the austenite in the heart while the hardened layer has good wear resistance. This is unmatched by other materials. However, the wear resistance of high manganese steel only shows its superiority under conditions sufficient to form work hardening, and is otherwise poor.

The typical Mn17 wear-resistant high-manganese steel is based on Mn13 steel, which increases the amount of manganese, improves the stability of austenite, prevents the precipitation of carbides, thereby improving the strength and plasticity of the steel, and the work hardening ability of the steel And abrasion resistance. For example, the life of the ZGMn18 railway fork used in the north is 20% -25% longer than that of ZGMn13. ^[2]

The temper of manganese steel is very weird and interesting: if 2.5-3.5% manganese is added to the steel, the low-manganese steel produced will be as crisp as glass and will break when knocked. However, if more than 13% of manganese is added to make high-manganese steel, it becomes both hard and tough. High-manganese steel becomes very soft when heated to a light orange color, making it easy to perform various processing. In addition, it is not magnetic and will not be attracted by magnets. At present, manganese steel is widely used to manufacture steel mills, ball bearings, buckets of bulldozers and excavators, and other frequently worn components, as well as rails and bridges. The roof of the audience hall of the newly-built cultural square in Shanghai uses a novel grid structure and is welded with thousands of manganese steel pipes. In a fan-shaped hall measuring 76 meters by 138 meters, there is no pillar in the middle. Because manganese steel is used as a structural material, it is very strong, and the material used is less than other steels. On average, only 45 kg of manganese steel is used per square meter of roof. In 1973, the healthy Shanghai Stadium (accommodating 18,000 people) also used manganese steel as the structural material for the roof of the grid. In the military, high-manganese steel is used to manufacture helmets, tank armor, and armor-piercing shells.

Due to the work hardening phenomenon of high manganese steel, the casting should be avoided as much as possible. The holes and grooves in the casting are cast as far as possible. But the processing of high manganese steel is not completely impossible. The tool trimming can be carried out after one infeed. The inevitable machining should be enlarged during the casting process design so that the infeed of the machining avoids the work hardening layer.

When the high-manganese steel is reheated, there is a brittle temperature range in which carbides precipitate between 250-800 ° C, and as-cast high-manganese steel also has network carbides and casting stress, so the welding performance is poor.

For high manganese steel castings, the riser or defects should be repaired after water toughening, and the welding should be quickly cooled after welding. In order to eliminate or minimize the heat affected zone, apply a small current, discontinuous welding, or water cooling while welding. The electrode is made of high manganese steel electrode or austenitic stainless steel electrode. If a work hardened layer is present, it should be removed before welding. ^[2]

High-manganese steel castings mostly adopt sand molding technology schemes. Sand casting is widely promoted due to mature technology and high production efficiency. There are also special castings. Special casting refers to a casting method that is significantly different from sand casting in terms of mold materials, molding methods, metal liquid filling forms, and metal solidification conditions in the mold. Special castings include: investment casting, metal casting, pressure casting, low pressure casting, back pressure casting, squeeze casting, centrifugal casting, lost foam casting, gypsum casting, ceramic precision casting, continuous casting, vacuum casting, fine casting Crystal casting, electromagnetic casting, etc. ^[2]