Q420E

GB/T 1591—1994, Table 1; Heat-analysis mass fractions wt%. Requirements from other current editions are not backfilled into this edition. V/Nb/Ti/Al in Table 1 are grain-refining elements; 5.1.1.6—8 requires at least one of C/D/E; A/B is optional and, when not added, is neither analyzed nor guaranteed; All four minima must not be imposed simultaneously as default requirements. For all 5.1.1.10 grades, residual Cr/Ni/Cu are each ≤0.30%; Table 1 of Q390/Q420/Q460 separately lists a Cr/Ni limit; interpret it according to whether the element is intentionally added as an alloying constituent. 5.1.1.4 sheet

hot-rolled strip has a thickness exception for the Mn minimum; The Nb minimum for 5.1.1.9 sections and bars is 0.005%; Special forms and contract conditions require manual review. This standard covers high-strength low-alloy structural steels; This does not establish cold-heading wire suitability, actual supply or a default mechanical-property guarantee. On the left of this section, scanned Table 1 is misprinted as a second group of Q460; Table 2 and 5.1.1.11/13 explicitly identify quality Q420; this row was reconciled by section/composition against Table 2, with the source ambiguity retained. Al≥0.015% in Table 1 is total aluminum; In the 5.1.1.6 grain-refining combination, at least one element must meet its corresponding minimum; all elements are not simultaneously mandatory.

Heat analysis, mass fractions wt%; Retain the identity of the 2008 edition; do not apply the 2018 edition.. ; When grain refining elements need to be added per 6.1.2, at least one of Al/Nb/V/Ti must be contained and specified in the quality certificate.; This clause does not provide mandatory general lower limits for all elements.. ; 6.1.4 When nitrogen-fixing alloying elements such as Al/Nb/V/Ti are added, N is not restricted, but the nitrogen-fixing elements must be specified.; If this condition is not selected, the N upper limit listed in the table is the default.. ; Table 1, Note a: For sections/bars, the P and S limits may each increase by 0.005%; the upper limit for quality class A may be 0.045%.; Cannot be used for other products.. ; Table 1 Note b: When grain refining elements are added in combination, Nb+V+Ti≤0.22% and Mo+Cr≤0.30%.; The individual-element upper limits cannot all be taken simultaneously.. ; Clause 6.1.6: RE is calculated as an addition of 0.02–0.20% of the molten-steel weight, not as guaranteed finished-product composition..

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.