--- title: Cast Iron Welding Repair in Reno | Wolf Machine url: https://wolfmachinenv.com/services/cast-iron-welding/ business: Wolf Machine & Fabrication, Inc. address: 4812 Longley Ln, Reno, NV 89502 phone: (775) 359-5570 hours: Shop Monday-Friday 7:00 am-3:30 pm; closed Saturday and Sunday type: Metal and plastic fabrication and machining (custom and CNC machining, welding, metal and plastic fabrication, gearbox and part repair, align boring, metal spray) --- [Photo: Stock photo: arc welding with a stick electrode, sparks in a dark shop] - [Home](https://wolfmachinenv.com/) - [Services](https://wolfmachinenv.com/services/) - Cast iron welding repair # Cast iron welding repair Many cracked cast iron parts can be repaired by welding, and we look at each one first to decide whether welding makes sense. Cast iron is brittle and cracks easily when heated and cooled unevenly, so the repair depends on locating the whole crack and controlling the heat. Stock photo: arc welding with a stick electrode, sparks in a dark shop Gear cases, pump bodies, housings and brackets are often cast iron, and they fail by cracking. Welding cast iron is a skill of its own because the metal behaves nothing like steel when it is heated. This page is about that repair. For the joint on steel parts, see the general welding page. ## At a glance - Cracks found first with Magnaflux - Preheat and slow cooling to protect the casting - Filler chosen for cast iron, often nickel based - Honest advice on whether to repair or replace - Machining after the weld, in the same shop Love working with these guys, and gal. Great customer service and knowledgeable skill base. They have helped with many big projects and have always pulled though when our machines went down. JoHannah W. ยท Google review, March 2017 [Leave us a Google review](https://search.google.com/local/writereview?placeid=ChIJVWVOfCI_mYARibcFMPsDEKc) ## Why cast iron cracks when it is welded Cast iron holds a lot of carbon, much of it as flakes of graphite. That makes it good for vibration damping and wear, and it also makes it brittle. A weld heats a small spot to melting while the metal around it stays cool, and cast iron cannot stretch to absorb that difference. The result is a new crack beside the weld. Fast cooling makes it worse. Carbon in the heated zone can form hard, brittle structures that crack as they cool, which is why the [heat-affected zone](https://wolfmachinenv.com/glossary/heat-affected-zone/) matters so much on castings. ## Find the whole crack before you weld Cast iron is magnetic, so [Magnaflux crack inspection](https://wolfmachinenv.com/services/magnaflux-inspection/) works well on it. Magnetic particles gather along a crack and show where it ends. A weld that stops short of the crack tip leaves the crack free to grow. Once the crack is mapped, it is opened up with a groove so the weld can reach the bottom. Drilling a small hole at each crack tip is a common general practice to stop it running further. ## Preheat, slow cooling and filler The usual approach on a casting is to warm the whole part evenly before welding, keep it warm during the work and let it cool slowly, often under insulation. This is the idea behind [preheat and interpass temperature](https://wolfmachinenv.com/glossary/preheat-and-interpass/). Short weld passes, peened lightly, also relieve stress. Filler for cast iron is often nickel based, because it stays soft enough to take the stress. Which approach fits depends on the casting, the crack and the job the part does. ## Repair or replace: we look at it first Some castings are better replaced, such as a part with many cracks, oil-soaked metal that will not accept a weld or a crack in a place that carries heavy load. We would rather tell you that after a look than weld a part that will fail again. The guide on [repair or replace](https://wolfmachinenv.com/guides/repair-or-replace/) sets out how to decide. Send photos of the crack from two sides, the machine the part came from and what the part does. If it is a housing that must be bored or faced after welding, mention that too, because it changes how much stock is left on. ### Sources - [Cast iron (welding section)](https://en.wikipedia.org/wiki/Cast_iron) (2026-10-18) - [Magnetic particle inspection (overview)](https://en.wikipedia.org/wiki/Magnetic_particle_inspection) (2026-10-18) ### Cast iron repairs - Gear cases and gearbox housings - Pump bodies and casings - Half carriers and other equipment housings - Brackets, bosses and mounting feet - Machine bases and covers with cracks ### Typical parts - Gear cases - Pump bodies - Housings - Brackets - Half carriers ### Materials [Steels and steel alloys](https://wolfmachinenv.com/materials/steel-and-steel-alloys/) [All materials we machine](https://wolfmachinenv.com/materials/) ### How to send us the job Start with whatever you have: the drawing, the old part, or clear photos and a few measurements. Attach files to the quote request or bring the piece to 4812 Longley Ln. [Request a quote](#quote) [What to put on a drawing](https://wolfmachinenv.com/guides/what-to-put-on-a-drawing/) ### Talk to the shop [(775) 359-5570](tel:(775)%20359-5570) | Monday to Friday | 7:00 am - 3:30 pm | |---|---| | Saturday and Sunday | Closed | [Request a quote](#quote) ### Related - [Welding, all types](https://wolfmachinenv.com/services/welding/) - [Magnaflux crack inspection](https://wolfmachinenv.com/services/magnaflux-inspection/) - [Gearbox repair and rebuilding](https://wolfmachinenv.com/services/gearbox-repair/) - [Preheat and interpass temperature](https://wolfmachinenv.com/glossary/preheat-and-interpass/) ### Questions about this service - [Can you weld aluminum?](https://wolfmachinenv.com/faq/can-you-weld-aluminum/) ### Terms on this page [Heat-affected zone (HAZ)](https://wolfmachinenv.com/glossary/heat-affected-zone/) [Preheat and interpass temperature](https://wolfmachinenv.com/glossary/preheat-and-interpass/) [The full glossary](https://wolfmachinenv.com/glossary/) ## Work from the shop [Photo: Looking into a perforated strainer basket: six welded flat-bar spokes meeting at a welded center hub] Job 05 Looking into a perforated strainer basket: six welded flat-bar spokes meeting at a welded center hub. [Photo: A tall conical strainer of perforated sheet, seam-welded and welded to a flat ring flange] Job 06 A tall conical strainer of perforated sheet, seam-welded and welded to a flat ring flange. [Photo: A custom-fabricated steel tank with a domed head, a bolted mid-body flange and nozzles, installed in a plant] Job 04 A custom-fabricated steel tank with a domed head, a bolted mid-body flange and nozzles, installed in a plant. [See all our work](https://wolfmachinenv.com/gallery/) ## Related services - [Welding, all types](https://wolfmachinenv.com/services/welding/) - [Aluminum welding](https://wolfmachinenv.com/services/aluminum-welding/) - [Stainless steel welding](https://wolfmachinenv.com/services/stainless-steel-welding/) - [Metal fabrication](https://wolfmachinenv.com/services/metal-fabrication/) - [Plastic fabrication and machining](https://wolfmachinenv.com/services/plastic-fabrication-and-machining/) - [Automated machines and fixtures](https://wolfmachinenv.com/services/automated-machines-and-fixtures/) ## Cast iron welding repair questions Still have a question? Call [(775) 359-5570](tel:(775)%20359-5570), Monday to Friday, 7:00 am to 3:30 pm. ### Can any cracked cast iron part be welded? Not every one. We look at the part first, locate the crack and judge whether a repair will hold. If replacing is the better choice, we say so. ### Do you preheat cast iron? Yes, preheat and slow cooling are standard practice on castings because uneven heat is what makes cast iron crack. [Photo: Stock photo: a lathe turning a bar, hot chips flying] ## Request a quote Tell us what you need, attach a drawing or photos of the part, and we will get back to you during shop hours. Free consultations; prompt estimates. [Call (775) 359-5570](tel:(775)%20359-5570) - From your specifications, drawings or samples. We can also assist you in designing your product or part. - Free consultations and prompt estimates - Stands behind the work: Our rates are very competitive and our quality is second-to-none. Wolf Machine stands behind the work we perform. - Company accounts: all major credit cards, or we can open an account for your company Shop hours Monday to Friday, 7:00 am to 3:30 pm. Send your request any time and we will get back to you during shop hours. Stock photo: a lathe turning a bar, hot chips flying