Q255A

Heat-analysis mass fractions wt%; Based on the original scan of page 2 Table 1 and Clauses 5.1.1.1–5.1.1.6, 5.1.2 of GB700–1988; The PDF consists of 3 pages including the cover; the full text of the remaining standard has not been obtained, and it shall not serve as the basis for mechanical property verification. ; First select the deoxidation method and smelting method. F rimmed steel Si ≤0.07%; b semi-killed steel Si ≤0.17%; Z/TZ killed steel Si lower limit 0.12%, upper limit per Table 1. Q235A/B rimmed steel Mn upper limit 0.60%. ; Grade D must contain sufficient grain-refining elements, such as acid-soluble aluminum ≥0.015% or total aluminum ≥0.020%; The current automated procedure distinguishes the two aluminum analysis bases; other grain-refining elements require separate confirmation and must not be treated as equivalent to total aluminum or acid-soluble aluminum. ; Residual Cr/Ni/Cu each ≤0.30%; Basic oxygen furnace steel N ≤0.008%. For other smelting methods, no N upper limit is given in this Clause; do not fill as zero. With purchaser's consent, Grade A Cu may be ≤0.35%, which must be analyzed and noted in the quality certificate; it is not adopted by default. ; As residual ≤0.080%; Use of arsenic-containing ore in steelmaking may be agreed between supplier and purchaser; Analysis may be omitted when raw materials contain no As. Do not arbitrarily fill in agreement upper limits if not provided. ; When mechanical properties are guaranteed, the C/Mn lower limits for Grade A and Mn lower limits for other grades need not be delivery requirements, but heat-analysis values must be stated in the quality certificate; The basic scope of this tool does not automatically cancel lower limits. ; For supplies of steel ingots or billets, the A/B chemical composition may be adjusted by agreement at the purchaser’s request; do not automatically apply unspecified values. Product-analysis tolerances follow GB222; Product-analysis deviations for rimmed-steel finished products or commercial billets are not guaranteed. ; The carbon structural steel standard does not imply that any delivery condition is suitable for cold heading; Specific applications shall be confirmed in conjunction with delivery condition, dimensions, process, and trial production.

A match in the materials database does not establish suitability for cold heading or guarantee finished-product strength. Confirmation must consider wire condition, deformation, heat treatment and tests on actual parts.