{"id":2214,"date":"2026-10-06T09:00:00","date_gmt":"2026-10-06T09:00:00","guid":{"rendered":"https:\/\/kurtfoundry.com\/?p=2214"},"modified":"2026-09-07T09:27:37","modified_gmt":"2026-09-07T09:27:37","slug":"how-to-repair-casting-defects","status":"publish","type":"post","link":"https:\/\/kurtfoundry.com\/fr\/blog\/how-to-repair-casting-defects\/","title":{"rendered":"Comment r\u00e9parer les d\u00e9fauts de coul\u00e9e"},"content":{"rendered":"\n

A casting defect is repaired by locating it with an NDT method that can actually see it, excavating all of the unsound metal, verifying the cavity is clean before an arc is struck, restoring the metal by welding or machining, heat treating when the repair passes a defined size, and reinspecting the repair to the casting’s original acceptance standard. What decides whether that is worth doing is not the defect’s name. It is the alloy, where the defect sits in the wall, and what your purchase order says.<\/p>\n\n\n\n

One naming point first, because it changes how the rest of this reads. ISO 11970 reserves repair welding<\/em> for work carried out after a casting has been in service; everything done in the foundry before delivery is production welding<\/em> \u2014 a manufacturing step, like machining.<\/p>\n\n\n\n

That distinction is commercial, not academic. ASTM steel casting standards place no restriction on how much production welding a producer may do to meet the specification, and the Steel Founders’ Society of America<\/a> argues that the loose use of the word “repair” is exactly why buyers read welding as evidence of a bad casting. What limits welding on your part is your purchase order, not the standard.<\/p>\n\n\n\n

Which Casting Defects Can Be Repaired?<\/h2>\n\n\n\n

Nearly any defect that is local can be repaired; what decides the disposition is its size, its depth into the wall, and the alloy \u2014 not what the defect is called.<\/p>\n\n\n\n

\n\n
Casting defect<\/th>\nCommon repair method<\/th>\nTypical repairability<\/th>\n<\/tr><\/thead>
Flash, fins, rough surfaces<\/td>Grinding \/ machining<\/td>Easy<\/td><\/tr>\n
Surface inclusions<\/td>Grind or machine out<\/td>Usually easy<\/td><\/tr>\n
Small blowholes<\/td>Grind + weld<\/td>Often repairable<\/td><\/tr>\n
Localized porosity<\/td>Excavation + welding<\/td>Often repairable<\/td><\/tr>\n
Leakage from microporosity<\/td>Through-wall weld repair, or HIP<\/td>Repairable; impregnation prohibited on steel<\/td><\/tr>\n
Shrinkage cavity<\/td>Excavation + weld repair<\/td>Depends on size\/location<\/td><\/tr>\n
Crack \/ hot tear<\/td>Grinding\/gouging + welding<\/td>Depends on application<\/td><\/tr>\n
Cast-iron crack<\/td>Welding or metal stitching<\/td>Often possible<\/td><\/tr>\n
Dimensional shortage<\/td>Weld buildup + machining<\/td>Sometimes<\/td><\/tr>\n
Distortion \/ warpage<\/td>Straightening \/ heat treatment<\/td>Sometimes<\/td><\/tr>\n
Cold shut \/ misrun<\/td>Weld repair or reject<\/td>Usually more critical<\/td><\/tr>\n
Major core shift<\/td>Usually reject<\/td>Difficult<\/td><\/tr>\n
Extensive shrinkage\/porosity<\/td>Usually reject<\/td>Poor candidate<\/td><\/tr>\n<\/tbody><\/table><\/figure>\n\n\n\n

Cast iron sits apart from steel in this table. A crack in gray and ductile iron castings<\/a> can be welded and often is, but the joint does not come back to parent properties \u2014 you get a repaired part, not an equivalent part.<\/p>\n\n\n\n

1. Inspect and Locate the Defect<\/h2>\n\n\n\n

Locate the defect with the NDT method that can actually see it<\/a>, and name that method on the purchase order \u2014 the wrong one will miss precisely what you care about.<\/p>\n\n\n\n

Visual examination comes first and is mandatory: the surface must be free of adhering sand, scale, cracks and hot tears. What the volumetric and surface methods add is bounded:<\/p>\n\n\n\n