Melting And Quality Inspection Of Nodular Iron Castings

Nodular Iron Castings Are Made By Smelting First And Then Casting. The Step Of Smelting Nodular Iron Castings Is Batching. According To The Batching List, Control The Chemical Composition Of The Original Molten Iron. It Is Required That The Air Volume Should Not Be Too Large When Melting To Prevent The Oxidation Of The Original Molten Iron. When It Is Finished, It Begins To Spheroidize. In The Process Of Spheroidizing Treatment Of Nodular Iron Castings, The Temperature Of Molten Iron Can Not Exceed 1400-1420 ℃; In The Process Of Spheroidizing Treatment, The Amount Of Rare Earth Ferrosilicon Magnesium Alloy Is About 2-3%, The Amount Of Which Depends On The Temperature Of Molten Iron And The Amount Of Sulfur. Then Pour A Proper Amount Of Molten Iron Into The Ladle According To The Proportion. The Stirring Shall Be Conducted In Two Directions: Clockwise And Counter Clockwise. The Slags Shall Be Cleaned As Much As Possible, And Then Inoculated With 75 × 0.3-0.6% Ferrosilicon. The Slags Shall Be Stirred And Poured. In Order To Ensure The Production Quality Of Nodular Iron Castings, It Is Necessary To Pass The Pre Furnace Inspection To Judge The Nodularization Quality And Guide The Production. The Inspection Method Must Be Accurate, Simple And Rapid. There Are Two Specific Methods, One Is The Observation Method Of Triangular Test Piece. The Good Performance Of Spheroidization Is That The Fracture Is Silvery White, There Is Obvious Shrinkage In The Middle, And There Is Concave Shrinkage On Both Sides Of Triangular Test Piece. Another Method Is Flame Inspection. After Spheroidizing, There Are Yellow And Red Flames On The Surface Of Molten Iron. The More Sparks, The Longer And The More Powerful They Are, The Better The Spheroidizing Is. However, When The Temperature Of Molten Iron Is High, The Flames Shrink. If There Are More Than Three Large Flames Larger Than 40 Mm, More And More Small Flames Or One Or Two Large Flames Mixed With More Than Ten Small Flames, The Spheroidization Effect Is Good. Of Course, It Is Not Enough To Master These, But Also Need To Test The Quality Of The Nodular Cast Iron. The First Is The Inspection Of The Appearance Defects Of The Ductile Iron Castings. During The Inspection, The Defects Exposed On The Surface Of The Castings Shall Be Observed With The Naked Eye Or With The Aid Of The Magnifying Glass And The Sharp Nose Hammer; The Dimensions Of The Castings Shall Be Inspected With The Aid Of The Measuring Tool, The Sample Plate And The Working Platform To See Whether They Meet The Requirements Of The Drawings, And The Weight Of The Castings Shall Be Inspected With The Aid Of Various Weighing Tools To See Whether They Are Within The Allowable Deviation Range. The Second Is The Surface Defect Inspection Of Nodular Iron Castings, Which Can Be Obtained By Fluorescent Inspection, Penetrant Inspection Or Liquid Penetrant Inspection And Coloring Method, So As To Judge The Overall Quality Of Nodular Iron Castings.