Manganese(Mn) Steel Castings Processes
Manganese(Mn) Steel Castings are widely used in various kinds of industries, especially in the high impact requirements condition. But due to technology limited, a lot of foundries lack of some professional acknowledge to cast Manganese(Mn) Steel Castings. Below there're some brief introductions on the processes for casting Manganese(Mn) Steel Castings.
First Process-Manganese(Mn) Steel Melting:
a.Chemical components preparating. Usually used Manganese steel are with lower C: 0.75%－1.45%, Mn:11.0%－14.0%(usually not less than 13%), Si≤0.5%(Percentage of Si will affect lots of the impact result, thus, should be as less as possible.), P≤0.07%(phosphorus is easily chemical reactive with manganese, thus, to control percentage of Mn, we should reduce percentage of P at a small amount.); Cr:2%(certain percentage of Chrome can increase the wear resistant of the castings.) To control the quality of castings, furnace burdens should not more than 25%.
b.Melting. Putting all chemical elements into the furnance with correct sequences. When temperture in furnance achieve at 1580－1600℃, deoxidizing agent should be pressed into the deepest areas of the furnance and isolated with air with covering agent. Some factory workers just sprinkle the aluminium silks or even aluminium scraps onto the steel water and do not cover, thus, the manganese steel water can not be deoxidized completely, which will affect quality of the final Manganese(Mn) Steel Castings.
Second-Manganese(Mn) Steel Casting technics designing.
The typical characteristics of manganese steel is solidification shrinkage rate is high, but heat dispersion is bad. Thus, during casting technics designing, casting shrinkage rate should be kept at 2.5%－2.7%. The longer the Manganese(Mn) Steel Castings, the higher the rate is. Pouring should be at low temperture but quick pouring action. To ensure the quality, sometime, we can also considering to put the chil iron inside during casting.
Third-Manganese(Mn) Steel Heat treating.
Below 350℃, temperature rising should be kept at <80℃/h; below 750℃, should be kept at <100℃/h. When temperture>750℃, the temperature should be rised quickly. When arrived at 1050℃, castings should be kept at certain temperature due to the thickness of the castings, then rised to 1100℃. After heating, castings have to be heardened in water quickly. The high Mn(manganese) steel heat treating characteristics is also special and different from other heat treating of other investment casting or sand casting processes.
Fourth-Manganese(Mn) Steel Cutting pouring gate and repair welding.
It's better to put the castings inside water, but keep pouring gate surface out of water, then cut the pouring gate, with about 1mm left to be grounded off. If repair welding required, correct process should be welding and hitting together to stress relief of the products.
Finally-Inspecting
a.Measuring the finished Manganese(Mn) Steel castings with certain testing instruments.
b.Do the NDT testing to ensure the surface and inside quality of the castings.