Why Wear Parts Chip, Break or Wear Through: Four Failure Modes Explained

When a wear part fails, the first reaction on site is usually that the material was poor — but more than 40 years of failure analysis since the 1980s shows that a significant share of failures are not material problems at all, but duty, assembly or operating issues. Sorting failure modes correctly is the only way to find the real root cause and avoid the cycle of buying better parts that still fail. This guide explains the appearance, metallurgical cause and investigation route for the four most common failure modes.

图：大美智造圆锥破衬板实物——每批随附材质成分单与热处理记录，支持失效件联合分析

I. Appearance and Metallurgical Cause of the Four Failure Modes

1. Chipping (brittle fracture)

• Appearance: Corners or loaded zones break away in chunks, with a flat, bright grey crystalline fracture surface and almost no plastic deformation — no stretching, no rolled edges;
• Metallurgical cause: Insufficient toughness. For manganese steel the most common cause is a grain boundary carbide network — heating, holding or cooling during water toughening was inadequate, carbides reprecipitated at grain boundaries and the material turned brittle;
• Often overlooked cause: Impact beyond design. Uncrushable objects in the feed (digging teeth, iron blocks) or feed lumps far exceeding the design feed opening deliver instantaneous loads beyond any material capability, and even compliant material will chip.

2. Fracture (fatigue or overload)

• Appearance: Fatigue fracture shows clear beach-mark striations with a crack origin point and a rougher final rupture zone; overload fracture is rough throughout and may show obvious plastic deformation;
• Metallurgical cause: Fatigue origins are usually stress raisers — casting defects (shrinkage, slag inclusions, porosity) or geometric discontinuities (sharp corners, section changes). The crack grows under cyclic loading until final rupture;
• Investigation: Origin point location, presence of casting defects there, and whether the load is cyclic.

3. Wear-through (abrasive wear)

• Appearance: The working face thins evenly with ploughing scratches on the surface, no fracture and no chipping;
• How to read it: The key is separating normal abrasive consumption from abnormally accelerated wear, judged by specific consumption (parts consumed per ton of ore). Normal specific consumption means normal wear; only clearly elevated consumption justifies investigating material or duty;
• Common accelerators: Feed more abrasive than assumed (for example limestone expected but quartz present), cavity distortion after liner wear concentrating load locally, or uneven feed distribution.

4. Deformation or collapse (plastic deformation)

• Appearance: The part bends, collapses or crushes locally with no fracture or chipping;
• Metallurgical cause: Insufficient hardness or sustained overload. Unlike chipping, plastic deformation means the material is too soft or has carried sustained excess load (prolonged choking, overloading);
• Investigation: Check as-delivered hardness against the expected band, then review operating records for prolonged overload or choking.

II. A Field Lesson: Harder Parts That Chipped Worse

A granite aggregate plant we served had cone crusher liners chipping away in chunks in the loaded zone. The plant blamed the material and replaced manganese liners with higher-hardness high chrome — the chipping became worse and life shorter still.

We ran the full failure mode analysis sequence:

• Step 1, appearance: The fracture surface was flat, bright grey with no plastic deformation — a brittle chip, not fatigue;
• Step 2, material and metallurgy: Sectioning the original manganese liner showed no significant grain boundary carbide network, so water toughening had largely been correct;
• Step 3, duty: Operating records and a site check revealed the upstream metal detector had not been cleaned for a long time and was effectively useless, letting tramp iron strike the liners directly, while feed lump size fluctuated with occasional oversized pieces.

The root cause was not material but failed metal removal plus oversized feed. That also explains why high chrome made it worse — harder but less tough, it chipped even faster under iron impact.

The fix: repair the metal detector and add it to the daily inspection list, install a grizzly ahead of the crusher to control lump size, and return the liner to a manganese-based solution. Chipping stopped. The rule recorded: read the fracture surface first, investigate duty second, discuss material last — reverse the order and you end up paying more for worse results.

图：失效分析实验室——断口形貌观察与金相检测是定位失效模式的关键手段

III. Root Cause Investigation Table (Save This)

Three-step analysis: 1. Read the appearance (photograph fracture surfaces and wear patterns, retain the failed part); 2. Find the cause (metallurgy, NDT and duty records in parallel); 3. Set the countermeasure based on the dominant mode rather than upgrading material blindly.

Note that one part can show different modes in different zones — for example chipping at the upper edge and wear-through at the lower edge. Identify the dominant zone first, otherwise one countermeasure is asked to cure two different problems. Manganese failure is closely tied to heat treatment quality; see GB/T 5680 Hadfield Steel Explained.

IV. Insider Gotchas

• Blaming material for every chip: Chipping may mean insufficient toughness (material or heat treatment) or tramp iron and oversized feed (duty). Switching material without checking duty can cost more and perform worse — high chrome is more brittle than manganese;
• Concluding without fracture analysis: Fatigue and brittle chipping need completely different countermeasures. The former points to casting defects and stress raisers, the latter to heat treatment and impact load. Without the fracture surface you are guessing;
• Treating normal wear as a fault: Even thinning with specific consumption inside the normal band is normal consumption and needs no cure; only clearly elevated consumption warrants investigating material or duty;
• Not retaining failed parts: The failed part is the best sample available. When abnormal failure occurs, keep it and photograph the fracture surface, wear zone and installation position, otherwise later analysis is impossible.

V. When NOT to Analyse This Deeply

• Low-value consumables: Full metallurgical analysis of screen mesh or bolts can cost more than the part; appearance assessment is enough;
• Duty already confirmed as the cause: If large iron pieces are confirmed in the feed, fix metal removal first rather than starting with metallurgy;
• End-of-life wear-through: Normal wear at the end of service life is expected; the priority is log updates and stocking, not analysis;
• Deformation on non-load-bearing parts: Guards and baffle plates deform from assembly or external forces and cannot be used to judge material quality.

FAQ

• Q: Does chipping mean the material was bad? A: Not necessarily. Chipping shows the material behaved brittly there, which may be insufficient toughness (grain boundary carbides in manganese steel) or impact overload from tramp iron or oversized feed. Read the fracture surface and check duty before concluding.
• Q: How do we tell fatigue from overload fracture? A: By the fracture surface. Fatigue shows beach-mark striations and a crack origin from progressive growth under cyclic load; overload is rough throughout with plastic deformation from a single excessive load. The countermeasures differ.
• Q: How do we know if fast liner wear is normal? A: Use specific consumption. Calculate parts consumed per ton of ore and compare with historical data for similar duty; even thinning inside the normal band is normal. Only clearly elevated consumption warrants investigating abrasiveness, cavity distortion or alloy match.
• Q: Is metallurgical analysis necessary? A: For critical parts, yes. Metallurgy directly exposes heat treatment problems such as grain boundary carbide networks, which chemistry certificates cannot reveal. Low-value consumables can be assessed by appearance alone.
• Q: Does Grand Heavy support failure analysis? A: Grand Heavy wear parts ship with material certificates and heat treatment records, and support joint appearance and metallurgical analysis when customers return failed parts. See also the purchase and acceptance checklist and the liner material decision matrix.

VI. Final Verdict

The sequence is always: read the fracture surface to identify the mode, then check metallurgy and duty for the cause, and only then discuss material and countermeasures. Reverse it and you get the loop of paying more for worse results. Turning every failure into reusable data is the real value of failure analysis. Foshan Grand Heavy Trading Co., Ltd. has built mining equipment and wear casting expertise for 40+ years, holds 20+ patents, partners with Central South University and Guangdong University of Technology, and is certified as a National High-Tech Enterprise [To be added: certificate number]. We serve CNBM, Conch Cement and clients across 6 overseas markets with 24-hour response from Guangzhou, Foshan and Changsha.

Grand Heavy — Read the fracture, check the duty, then discuss material!