Tape measure, band saw, automobile seat belt return spring,
As far as spring manganese steel is concerned, it is mostly difficult to weld.
As a kind of structure (such as grid, bridge, truss), some manganese steels need to ensure welding performance, or they can be connected by rivets without welding.
As far as bearings are concerned, chromium steel is generally used. The temper of manganese steel is very strange and interesting: if 2.5-3.5% manganese is added to the steel, the low manganese steel will be as brittle as glass and will break when knocked. However, if more than 13% manganese is added to make high manganese steel, it will become hard and tough. When high manganese steel is heated to light orange, it becomes very soft and easy to process. In addition, it has no magnetism and will not be attracted by magnets. At present, manganese steel is widely used in the manufacture of often worn parts such as steel mills, ball bearings, buckets of bulldozers and excavators, as well as railway tracks and bridges. The roof of the audience hall of Shanghai New Cultural Square adopts a novel grid structure, which is welded by thousands of manganese steel pipes. The fan-shaped hall is 76 meters long and 138 meters wide, without a pillar in the middle. Because manganese steel is used as structural material, it is very strong, and the materials used are less than other steels, with an average of only 45 kilograms of manganese steel per square meter of roof. 1973 Xingjian Shanghai Gymnasium (accommodating 18000 people) also uses manganese steel as the structural material of the grid roof. Militarily, high manganese steel is used to make helmets, tank armor and penetrators. When refining manganese steel, soft tin ore containing 60-70% manganese is mixed with iron ore.
Besides manganese steel, manganese steel is also an important manganese alloy. Manganese steel contains 30% manganese and has good mechanical strength. The "Mn-Cu alloy" (also called "Mn-Ni-Cu alloy"), which is composed of 84% steel, 12% manganese and 4% nickel, has little change in resistance with temperature and is used to manufacture precise electrical instruments.