Selection Guide for Grizzly Screen Bars Material Grades: Mn13 or Mn18
When a grizzly screen starts losing bars, the whole crushing circuit suffers. Throughput drops, maintenance crews work overtime, and operating costs climb fast. Choosing the correct material grade for your Grizzly Screen Bars may look like a small decision, but it directly impacts wear life and downtime. Mn13 and Mn18 are both high‑manganese steels with strong wear resistance, yet they perform very differently in real service. Understanding those differences helps you avoid premature failures and get the most out of every replacement.
Mn13: The Reliable Workhorse
Mn13—most people just call it Hadfield steel—has been the go‑to for Grizzly Screen Bars for ages. With about 13% manganese and 1.2% carbon, its real magic is in work hardening. Every hit makes the surface tougher, but the core stays strong and resilient. That means it soaks up hard knocks without breaking. If you're dealing with medium‑hard rock, average‑sized feed, and a steady workload, Mn13 nails that sweet spot between toughness, long life, and reasonable cost. Lots of quarries and recycling operations stick with Mn13 because it simply works. You get solid, reliable performance without blowing your budget—it's still the smart choice for moderate‑duty screening.
Mn13, typically containing around 1.0–1.4% carbon and 11–14% manganese, is the classic Hadfield steel that made the name "manganese" synonymous with impact resistance in mining. The magic of Mn13 on a Grizzly Screen is that in its delivered, solution-annealed condition it is surprisingly soft—around 200 Brinell—which makes it incredibly tough and ductile, able to absorb massive impact energy without cracking. The moment a heavy rock hits it, the surface work-hardens to 500+ HB while the interior remains shock-absorbent, creating a self-protecting wear surface. This is why Mn13 dominates in scalping duties with large top size, high drop heights, and mixed feed where occasional massive boulders arrive without warning. The catch—and it is a big one—is that Mn13 needs impact to earn its keep. In a Grizzly Screen running light feed, small top size, or low drop height, the bars never see enough energy to trigger meaningful work hardening, so they wear as soft steel, gall, deform plastically, and develop a wavy top surface that destroys the opening profile. Plants that complain about Mn13 "going soft" usually have a feed problem, not a material problem: the bars are being rubbed by fines and small stones instead of being hammered by lumps, so the hardening reaction never fires.
Mn18: When the Rock Wins the First Round
Mn18 pushes manganese content to roughly 17–19% with slightly adjusted carbon, and the result is a steel that starts harder, work-hardens faster, and reaches higher surface hardness than Mn13 under the same impact. On a Grizzly Screen handling extremely abrasive, high-density, or large-top-size material—think banded iron formation, quartzite, granite with high compressive strength, or recycled concrete with rebar—Mn18 earns its premium by hardening more aggressively and resisting the gouging wear that slowly destroys Mn13 in the same duty. The higher manganese content also improves resistance to deformation in the as-delivered state, so if your screen deck sits in a circuit where the bars take repeated moderate-to-heavy blows but not the occasional 10-tonne shock that Mn13 loves, Mn18 often outlasts it. The trade-off is cost and weldability: Mn18 is more expensive per tonne, more sensitive to overheating during any on-site modification, and if the impact energy is genuinely high enough to fully activate work hardening, Mn13 can match it at lower cost.
Matching the Bar to the Circuit, Not the Catalog
The decision between Mn13 and Mn18 for a Grizzly Screen should start with three numbers: top size as a percentage of bar opening, drop height from feeder to bar, and abrasiveness of the rock measured as silica content or compressive strength. A simple rule that holds up in the field: if top size exceeds 40% of the bar gap and drop height is over 1.5 meters with competent rock, Mn18 is usually the safer bet because the bars need to harden fast and stay dimensionally stable; if top size is smaller, feed is mixed with plenty of fines cushioning the impact, or the circuit includes a grizzly feeder that pre-scales the worst lumps, Mn13 often delivers 80–90% of the life at significantly lower cost. Support spacing and bar profile matter just as much as alloy: a Mn18 bar spanning too far between supports will deflect and work-harden unevenly, creating stress concentrations that lead to fatigue cracking at the root, while a Mn13 bar on too-tight a pitch wastes money on material that never gets properly loaded. Some plants run a split strategy—Mn18 on the feed-end bars where impact is savage, Mn13 on the discharge end where the rock is smaller and the wear is more about sliding abrasion than impact.
Mn18: Built for Severe Abrasion
Mn18 raises manganese content to about 18%, which intensifies work hardening and boosts resistance to abrasive wear. As a result, Grizzly Screen Bars made from Mn18 hold their profile longer in aggressive duties. The trade‑off is reduced toughness—under extremely large, angular, high‑impact loads, brittle fracture becomes a risk. But where high‑pressure sliding abrasion dominates, such as primary scalping of hard, gritty material, Mn18 usually lasts longer. Plants struggling with bars wearing thin or rounding off often benefit from switching grades, since Mn18 preserves both edge shape and screening efficiency over a longer interval.
Choose by Your Actual Wear Pattern
Neither grade wins in every situation. Feed hardness, lump size, moisture, and bar design all influence wear. A practical method is to review the wear history of your existing Grizzly Screen Bars: frequent cracking points toward Mn13, while gradual thinning or profile loss favors Mn18. Matching the steel to the real duty is what unlocks its full value.
Material grade is more than a metallurgical detail—it is a direct way to cut downtime and control maintenance costs. If you are unsure which grade fits your plant, share your operating conditions with our team. We will help you select the right Grizzly Screen Bars for reliable, long‑term performance.
