High-Chromium Sintering Grate Bars for Steel Mills: A Warpage Reduction Case Study

Sintering plants live and die by grate bar warpage. A northern China steel mill (one of the 300-ton-converter-class clients in XRJ’s ladle/ladle-car ecosystem) reported that imported bars bowed after 6 weeks under 1100 °C sinter bed + alternating cool-air purge.

XinRuiJi supplied High Chromium Steel Iron Casting Grate Bars​ (listed on foundbased.com) with three changes:

1. Alloy: Cr 28–32%, Ni balanced for thermal fatigue, N-added for creep resistance

2. Casting: shell mold for consistent 12 mm web thickness; gating redesigned to feed the long thin end first, eliminating shrinkage at the air-cooled tip

3. Finish: shot blast + stress relief; laser-marked heat number per bar

Field data

· Warpage < 1.5 mm after 11 weeks (vs. 4–6 mm before)

· No fracture in 8000-bar first lot

· Sinter strand downtime for bar swap cut from 2 shifts to 1

Because XinRuiJi also makes ladles and new-energy ladle cars, the steel mill sourced grate bars + a 120 t hot-metal ladle spare from one QC system—same spectro lab, same dimensional room.

Product card (for listing reuse)

· Item: Pelletizing / Sintering Grate Bar, Hi-Cr cast iron

· Use: sintering machine, industrial boiler, WtE optional

· Cap: 800 t/y, MOQ 50 pcs, T/T, plywood pack, Shanghai

· Standard: ASTM A297 reference, Ra6.3