ML30CR

GB/T28906-2025 Table 3: Hot-rolled wire rod of quenching-and-tempering-type cold-heading steel; heat analysis, mass fraction %.. ; Note a: Aluminum may be added to improve cold-heading performance, with Alt≤0.060%; this option does not make addition mandatory by default.. ; Note b: Through negotiation between the supplier and the buyer, Si may be lower than 0.10%; In this case, aluminum must be added and Alt≥0.020%.. This record defaults to the Si range listed in the table; do not arbitrarily fill in when no specific low-silicon agreement range is given. ; Note c: For the first 11 grades in Table 3, Cr may be added by agreement to improve hardenability and mechanical properties; the addition amount must be confirmed by both parties; When no agreement is provided, residual Cr ≤ 0.20% according to 7.1.5. ; 7.1.5 Residual Cr, Ni, and Cu are each ≤ 0.20%, and residual Sn ≤ 0.06%; The residual Cr upper limit is not applicable when Cr has a listed alloy range in the table. ; 7.1.7 Unless otherwise specified in the table, the permissible deviation of the finished product chemical composition shall be according to GB/T222; heat analysis values shall not be substituted for finished product tolerances. ; The original text applies to 5–52mm hot-rolled wire rod for cold heading; specific product specifications, supply, and processing routes still need to be confirmed; Mechanical properties to be verified separately.

Table 3 Heat analysis, mass fraction %. ; 6.1.5 residual Cr/Ni/Cu are each ≤0.20%; Listed alloy Cr is not subject to residual Cr limits. ; 6.1.7 composition tolerances follow GB/T222; Do not treat heat analysis limits as product analysis tolerances. ; Table 3 of the 2012 edition does not have the optional aluminum and low silicon footnotes of the 2025 edition; new edition conditions shall not be applied. ; Clause 6.4.2: Steel types intended for quenching and tempering normally do not require mechanical-property testing.; If requested by the purchaser, agree the property values for the hot-rolled condition or heat-treated test specimens and state them in the contract; do not invent uniform guaranteed values..

Table 3: Heat analysis of quenching-and-tempering-type steels for cold heading and cold extrusion; mass fraction %.. ; 6.1.5 Residual Cr/Ni/Cu each ≤0.20%; the residual Cr limit shall not be used when an alloy Cr range is specified. ; 6.1.7 Permissible deviations of finished product composition shall be in accordance with GB/T222; This record does not widen the default heat-analysis limits by applying product-analysis tolerances.. ; Table 3 of this edition does not specify optional Al or a unified low Si agreement; conditions of GB28906-2025 shall not be applied. ; Unspecified elements such as Mo shall not be assumed zero; Specific product forms, delivery, mechanical properties, and applicability to part forming still require separate verification.