Summary: On 22 October the China Steel Construction Society released the outline of its 15th Five-Year Plan: 130 million tonnes of steel structure consumption by 2030, rolled sections above 30 percent, high-strength steel as the mainstream grade. For buyers, three numbers on the media order change with it.

Mali Steel Shot followed the annual congress held in Taiyuan on 21-22 October, where more than 700 delegates reviewed the China Steel Construction Society's 15th Five-Year Plan and the 2035 action plan. The headline targets are fixed: 130 million tonnes of steel structure consumption by the end of 2030, about 15 percent of national crude steel output; CNC coverage of key manufacturing processes no lower than 70 percent; labour productivity no lower than 180 tonnes per employee per year.

In 2023 the industry processed roughly 112 million tonnes, just over 11 percent of crude steel. Reaching 15 percent in seven years means growth of about 3 percent a year. The market does not expand much. Its composition does.

Two further targets matter more to a blasting line. Rolled sections must rise above 30 percent of steel used, while plate currently accounts for more than 60 percent and hot-rolled sections less than 20 percent. Strength grades shift to Q355, Q390, Q420 and above, where Q235 and Q355 today make up about 80 percent and Q460 and above only about 2 percent.

Why section steel changes the abrasive mix

A flat plate is forgiving. Shot arrives at a right angle, oxide scale breaks, Sa 2.5 is reached with a single S330 charge. A rolled section is not forgiving. The web-to-flange fillet, the internal corner of a box column, the back of a gusset plate: none of these see the wheel directly.

The practical answer is two layers. S460 carries the main blast so thick flanges and heavy scale still break down. Angular grit in the G18 to G25 range follows into fillets and weld toes, cutting rather than peening. Shot does the impact work, grit does the scraping, and both run through the same machine. Roughness holds in the Rz 40 to 75 micron window that coating systems are specified against.

Higher strength also raises the hardness requirement on the media itself. A Q460 surface is harder than Q235, and media that is too soft fractures before it removes anything. Our internal standard Q/HX 001-2026 caps non-spherical particles at 5 percent, sulphur and phosphorus at 0.03 percent each, requires density above 7.4 g/cm3 and a cyclic life of at least 2,200 cycles. Those four figures decide the media cost per tonne of fabrication.

What 180 tonnes per employee means at the blast machine

Productivity of 180 tonnes per person per year is total output divided by total headcount. No fabricator reaches it by adding operators. The machine has to keep running.

On a blast line, a large share of lost time sits in charging and screening. Worn media breaks down quickly; a dust collector can pull tens of kilograms of fines and broken shot in a day, and each recharge costs 20 minutes or more. Move cyclic life from roughly 1,200 cycles to above 2,200 and the number of recharges roughly halves at the same output.

The arithmetic is easy to check. Take one month of records, add up charging, screening and parts replacement time, divide by monthly output. The result is minutes of blasting per tonne. If it will not come down, check the breakage rate of the media before blaming the machine.

Coating prices are quoted by film thickness, not by paint brand

A tender published for public comment between 22 and 26 October by Qinghai Xikuang Hangxiao Steel Structure priced blast cleaning and painting as an outsourced service in four bands: 210 RMB per tonne below 80 microns of dry film, 350 RMB for 81 to 160 microns, 440 RMB for 161 to 240 microns, and 510 RMB for 241 to 320 microns. The two shortlisted bidders differ by 15 to 20 RMB within a band; adjacent bands differ by 130 to 140 RMB.

The lesson is that coating cost is driven by how many coats are needed and how thick the film must be, and film thickness is set by the substrate. If the surface falls short of Sa 2.5, or roughness swings between Rz 30 and Rz 110, paint will not hold and thickness has to compensate. The quote moves up a band.

Before negotiating an outsourcing price, inspect the substrate your own shop produces. Inconsistent grit grading and poor dust removal push every supplier toward the higher band.

Questions buyers ask

Q: Do we need to replace shot entirely for Q420 and Q460?

A: No, add a grade. Keep S330 for thin plate and general work, add S460 for thick plate and large sections, and use G18 to G25 angular grit for fillets and weld toes. Hardness should sit at HRC 45 or above for Q460.

Q: What consumption per tonne is normal?

A: 100 to 150 kg per tonne of fabrication is the usual range. Section-heavy work with many blind spots runs higher. Anything below 100 kg usually means either simple geometry or incomplete metering.

Q: How do we compare two outsourcing quotes that look identical?

A: Compare the film-thickness band first, then the price. A 350 RMB quote can mean 81 to 160 microns at one shop and a compressed 161 to 240 microns at another. Match the band before matching the number.

Mali Steel Shot (Wuhan Hongxin Lixin Metal Products) has supplied metallic abrasives for 25 years: alloy steel shot S230 to S780, stainless cut wire shot 0.3 to 2.5 mm, high-carbon and high-manganese cut wire shot, and angular grit G12 to G120. Free samples for trial blasting. Website http://www.sisball.com/ , hotline +86 400-038-8928.