本發明提供一種船用氣閥鋼及其制備工藝,包括以下質量百分比的組分:C0.22?0.28%、Si0.7?1.3%、Mn0.7?1.3%、S≤0.02%、P≤0.035%、Cr19.1?19.8%、Ni9.1?9.8%、W1.8?2.5%、Mo0.05%,余量為Fe。本發明以Fe為基體,通過成分設計,控制各元素的質量百分比,Ni、Mo等元素含量均得到削減,實現了成分的減量化,在保證鋼材的耐高溫腐蝕性能以及強度、硬度等性能的基礎上進一步改善鋼材的塑性,降低氣閥鋼的生產成本

表1 鋼的牌號及化學成分

Table 1  steel grade and chemical composition

注：鋼的成品化學成分允許偏差按GB/T222的有關規定執行。

Note:The permissible tolerances of product analysis shall be as per the rules of GB/T222.

4.2 冶煉方法 Steelmaking method

鋼應采用“電弧爐+電渣重熔"的方法冶煉，或非真空感應+電渣。

The steelmaking process shall be EAF+ESR or Non Vacuum Induction

Melting+Electrical Slag Remelting (Non-VIM/IM+ESR) .

4.3 交貨狀態 Selivery condition

鋼棒應以“固溶+削皮+拋光"狀態交貨，表面粗糙度Ra≦1.6μm。

Steel bars shall be delivered in “solution plus peeling plus polishing",and the suiface roughness Ra shall be no more than 1.0μm.

推薦的固溶處理制度為：980～1050℃保溫，快冷。

The solution treatment system is recommended as “solution at 980～1050℃,and rapid cooling".

4.4 低倍組織 Macrostructure

低倍組織按GB/T226檢驗，鋼棒的橫截面酸浸低倍片上不得有目視可見的縮了殘余、氣泡、夾雜和裂紋。按GB/T1979 進行評定，一般疏松、中心疏松及偏析不得超過2.0級。

Cross-section macrostructure test pieces shall be etched and tested as per GB/T226,and they shall be free from visible shrinkage,bubble,crack and inclusion.The acceptable ratings are as follows:General porosilty≦class 2.0,central porosity ≦class 2.0,ingot setregation ≦class 2.0.

4.5 非金屬夾雜物 Non-metallic inclusion

鋼棒的非金屬夾雜物按GB/T10561中的評級圖評定，應符合表2的規定。

The non-metallic inclusion of steel bars shall be evaluated in accordance with GB/T10561,and the acceptable level shall conform to requirements of Table 2.

表2 非金屬夾雜物要求

4.6 晶粒度 Grain Size

交貨狀態的鋼棒的晶粒度應按GB/T6394檢驗，晶粒度應不粗于6級。

The grain size of steel bars in the delivery condition shall be tested as per GB/T6394,and the grain size shall be no coarser than No.6.

4.7 機械性能 Mechanical property

交貨狀態鋼棒的機械性能應符合表3的要求。

The mechanical property of steel bars in the delivery condition shall be as per requirements of Table 3.

表3 機械性能要求

Table 3 Mechanical Property at room temperature

4.8 超聲波探傷 Ultrasonic testing

鋼棒應逐支按照GB/T4162進行超聲波探傷。尺寸≦115mm的棒材按*驗收：>115-250mm的棒材按B級驗收。

Ultrasonic testing shall be performed in accordance with GB/T4162 for each piece of steel bar respectively with Class A acceptable for bars with the dimension of no more than 115mm and Class B acceptable for bars with the dimension ranging from 115mm to 250mm.

4.9 表面質量 Surface quality

鋼棒表面不允許有任何裂紋、折疊、劃傷等有影響使用的缺陷。

The surface of steel bars shall be free from any crack,loerlap,scratch and other defects that can influence the use of bars.